Seeing as your "fiscally responsible" party has no interest in that, I think chances of that happening are 0. also: government is not the same as a household.
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Bernie Sanders unveils $16 trillion ‘Green New Deal’ plan
- Thread starter Exellus
- Start date
Seeing as your "fiscally responsible" party has no interest in that, I think chances of that happening are 0. also: government is not the same as a household.
I mean, considering I think as part of the solution for dealing with climate change new nuclear plants need to be built, yes, 20 years before the existing ones are shutdown is far too short to me considering that shouldn't be happening for something like , I don't know when exactly, but nowhere near that soon since they aren't the enemy here and that's like I have no clue, a century off thing before we start worrying about getting rid of nuclear power but I certainly feel there really shouldn't even be guidelines for something like that at this point since that shouldn't be the priority right now, but rather dealing with climate change.
Or, an alternative answer: if we're still (for well-intentioned reasons and due to genuine concerns, but all the same) going at each others throats in 20 years due to factors like how much meat we do or don't eat, or how much electricity we are or aren't using on stuff like AC in 20 years (which are valid concerns, and need to be part of the discussion, but at the same time pail in comparison to stuff like institutional measures and where we're getting our power from in the first place) and that stuff is also part of the discussion (which they almost assuredly will be and if anything will only get louder as the problems get worse), then yes, that's too short, as it's something I don't feel should even be happening at all in the first place at this point, nevermind the timeframe itself as all hands need to be on deck because of how serious climate change is and I don't see how "all hands on deck" doesn't at all include nuclear as part of that and how it benefits anyone to just leave it and treat it as a sideshow where the energy from our electrical grid is coming from in the first place, how its generated, and how we best ensure our energy needs are met while making sure those sources are as carbon-neutral as possible. That's the exact opposite of a sideshow and is critical to this discussion, central to its very core, so I don't see how in any way it can just be pushed to the side like that, not in good faith any way, especially if we're serious about doing everything we can to fight in and not taking any half-measures.
Like seriously though. How is that not critical to the discussion, where are energy is coming from and how we're going to transition away from fossil fuels exactly, how to best do that, to lower our carbon emissions while still making sure people's energy needs are met? The sources for where we're get our electricity instead are absolutely core to that discussion, and if we're going to transition away from fossil fuels, while still meeting people's needs, and doing so in a carbon neutral way, nuclear absolutely at the very least needs to be a part of that discussion and is anything but a sideshow like the person I quoted was saying. That I just don't get at all, on any level, especially when we're being so ambitious and reaching for the stars elsewhere like with this 2030 goal. Are we all hands on deck like Sanders wants to be? Because climate change is that serious? Then how is nuclear not part of that and is somehow the enemy here instead or not worth bothering with? I just don't get it at all and it's making an enemy of the wrong things at the wrong time and I just don't get it at all.
Is climate change serious, or isn't it? Do we have the time to be choosy and picky about how we do these things and mess around with this or that, or do we have to do a lot of stuff that we might not like and may not be the most comfortable for a while and make some sacrifices to deal with this? Which is it? Because that's one of the things that's at the core of this for me, that I didn't think we did have the time to be picky about this, and that's what people like Sanders is trying to get through people's head with proposals like this, that we don't have time to mess around with climate change, that it's already that serious. ...Except when nuclear, when apparently climate change isn't that big of a deal anymore, and we suddenly do like the luxury of messing around and being picky and choosy about how we do things and can just toss stuff like that out of hand after all? We do have those luxuries? Then why is, say, 2030, so important? Apparently we have flexibility after all, so why not 2040 or 2050 even, since apparently we have the luxury to be flexible after all? Or don't we? But then why the flexibility with nuclear of all things, is it a crisis and all hands need to be on deck and we need to do whatever we can or can we be all picky and choosy and turn into NIMBYs about certain things if we like, do we have the luxury to do that kinda stuff after all? Because that's what I just don't get from proposals like this and leaves me completely confused, and I hope you can at least get where I'm coming from on that even if you don't personally agree with me.
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Irrealistic, a gift to natural gas companies and a waste of time given our goals in terms of CO2 emissions.
I swear to god, the hatred towards nuclear energy from so-called ecologists is going to kill us all.
EDIT : also a potential ecologic disaster for land use and mining.
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My point is that there still is no moratorium on plants with pre-existing licenses under Sanders' plan, and the ones that have already been through their first renewal have already been subject to regulatory checks to make sure they can remain operational for another 20 years, but I do agree that something will need to be done about the fact that they'd just be in limbo amidst increased advancements in other technologies and infrastructure.
Ok, I can understand where you're coming from here, but this is not the same argument as "why can't we use nuclear to help in the intermediary phase?" Nuclear is still going to be used in some capacity for many years under Sanders' plan. Essentially what you're saying is that the intermediary period where nuclear is still in use needs to be longer than just a couple of decades. I'd say that, personally I'd prefer it that way, but it's definitely not a necessity.
They're still basically saying "you fucked up" they were just doing so politely. They were also doing so politely before. You read the counterpoints, right? They're pretty much saying that his references are bunk and he bases the entirety of his study on things neither he nor his references go into any significant detail on. Jacobsons counter to this is basically a long-winded "well, since I didn't go into detail you can't say I'm DEFINITELY wrong" and their point is they never said he's DEFINITELY wrong just that there's a ton of data that says otherwise and his case wasn't based in very much fact. It's sorta a devil's proof assertion.
Also, if you wanna fall back on the other studies Jacobson references:
There was also a counter-response to that.
And let's just focus in on this point for starters since he uses a bunch of individual country studies (countries with 60% hydro, for example):
They also make the point that Jacobson is basically making an infinite resource assertion and that all the studies he says backs him up are made by 5 different groups in TOTAL including himself.
It's funny because some of them even include natural gas and they fudged the carbon foot-print of natural gas to be 2% of what it is currently to make the assertion of more massive carbon emissions reductions. Other plans are entirely biomass based and use a minimum amount of solar/wind.
For example:
Side note, that study only gets to 80% as well. And the study after that only gets to 50% renewable yet he still cites it as proof that we can get to 100%. Yet another one of those studies is only about same-day storage, not long term as would be needed for 100% renewable, and like almost all these studies, they ignore transmission and infrastructure costs the Rasmussen study itself says that storage might not even be feasible and is mostly just a thought-experiment.
... And actually most of these studies don't have 100% renewable looking into it in detail.
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Thanks for this. Happy for the commitment and it says all the right things. The devil of course is in the details, of course. Would for instance like to say far more commitment to integrating wildlife crossings in road building plans, and a big push in better integrating citizen science (which has the potential to give far more detailed coverage on species presence / absence) into biodiversity planning.
Its surreal how we are describing military intervention to save the Amazon, yet somepeople are still trying to poo poo a large scale investment into America itself to stop our own propagation of greenhouse emissions and the industries that support it.
I don't have a lot of time to respond to this in detail, but there are a few things I wanted to say...
The most recent references (the 42 peer-reviewed studies w/77 authors referenced in 2019) supersede the ones that Clack et al. responded to (the collation of that data is more recent), and most of those studies do indeed reach 100% renewable, even if they're not all projected within the 2030 time-frame. This is the most important point and is what's most relevant to this thread. The hyperfocus on Jacobson when he's not even connected to most of those studies is a distraction, albeit one I've indulged in for probably far too long for the sake of being charitable.
Handwaving away studies that have actually done the legwork to show that 100% renewal without nuclear is possible to focus on the studies with flawed methodology really misses the point, because we're talking about whether it's possible or not (and you don't need many studies to prove that) not whether or not it is the best plan or the most likely to hit its goals optimally.
Basically, addressing climate change can be done with or without nuclear, that's a fact, and that's my point. Should it be done without nuclear? I don't think so, no, it would be imprudent and not as practical as using nuclear, but I was never making the argument that nuclear should be removed from the equation (that is part of Jacobson's argument [and Bernie's plan for that matter], and the main part I disagree with).
Despite my gripes about Bernie's anti-nuclear stance, there are so many other aspects that his plan touches on that I'm willing to overlook the fact that his plan isn't laid out exactly as I would have preferred.
Yeah, the details will probably be spelled out in actual policy proposals for each of the segments of the plan. Can't wait to see them.
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I don't know guys, maybe it's easier to keep our goals realistic and resign ourselves to a slow miserable death
E: the nature of this problem means that every plan is simultaneously "unrealistic" while also not being ambitious enough to entirely solve the problem. I like this plan, though tbh i'd prefer if it went harder in some areas. It's as aggressive as any i've seen though, and therefore probably the best.
E: the nature of this problem means that every plan is simultaneously "unrealistic" while also not being ambitious enough to entirely solve the problem. I like this plan, though tbh i'd prefer if it went harder in some areas. It's as aggressive as any i've seen though, and therefore probably the best.
maybe we can have a debate with mother nature and find some middle ground
Depending on my motives, I could "debunk" the "realism" of any predictive model that suggests that we'd be able to save ourselves from the effects of climate change (nuclear or no nuclear, expensive or relatively inexpensive), on the account of the myriad of variables that are simply impossible to predict and aren't accounted for in any model. After all, we don't actually know what Earth will look like in 50-100 years should it be bombarded with unfathomable natural disasters and catastrophic events. I guess we should just give up and accept our fate. /s
Yep and somehow the fact that it's projected to pay for itself in an attempt to save the planet gets overlooked.
Pay for itself -- even before we factor in the "preventative care" savings. The costs of mitigating climate change now are orders of magnitude less than the costs will be later (the upper end of the cost being "every dollar civilization has to spend forever" )
He's right you know.....coming generations will mockingly refer to people, today and yesteryear, the cowards who have the gall to argue that the "In-feasibility" of aggressive climate action due to "cost" was worth the coming loss of life, destruction and suffering to this planet.
I don't get it. What's so bad about adding geoengineering to the fight against climate change? I also don't understand the idea that nuclear isn't a strong source of help in achieving going away from fossil fuels. It feels anti-science. It's clear the enemy are fossil fuels. That's it.
On this issue, I can't agree with Bernie and whoever advised him. Actually think Yang is better in this area even though Bernie is better in other areas.
How about rather than viewing everything in 1's and 0's, we try to look for something which will actually help people? There's more options here than Bernie's plan and death. There had better be, otherwise you'd be correct we're fucked. That's why it's important for our leaders to find these solutions for us.
Anything truly unrealistic is dead air when it comes to getting anything implemented, is the issue. Why bother wasting everyone's time and giving people false hope when you can spend that laser focused on the possible? It being aggressive is exactly the sort of thing which will backfire against moderate and conservatives, and leaves it vulnerable to state's crippling it further still and then there's the Supreme Court.
This is the kind of thinking that talks yourself out of asking for a raise when you're drastically underpaid (and you have hard data to prove it), because maybe you won't get it.
The thing with negotiation -- and politics is a negotiation -- is that if you neuter your own plans to accommodate the other side, they will still ask for more.
Furthermore, this isn't an ordinary political issue. Half measures on climate change are close to pointless. Go big or fuck off.
I'm glad that you realize that capitalism is basically a death cult and has us on the path to an apocalyptic world. It must be dismantled if we are to save ourselves. Anything short of that will not be enough.
How economically viable is it for a large die off of the global population? Total coastal loss? A vast decrase in farmable land and crop yields?
Why do idiots focus on extant deficits rather than the gargantuan wave of what will be lost?
Why do idiots focus on extant deficits rather than the gargantuan wave of what will be lost?
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Liberals look at a burning building with people burning inside and ask how much it will cost to put the fire out. They ask how much it will cost and if we can cover that cost, but completely ignore that people will die. I'm sorry, people are DYING RIGHT NOW because of climate change, but yeah, let's worry about how much it's going to cost.
The problem I have with this line of logic is that you keep stopping the train because it gets to the conclusion.
Who defines what's possible? Who defines what's realistic?
According to you it's the "moderates and conservatives".
Why (to them) is not possible?
We can follow this and say that anything that will cause disruption to the status quo is something this group of people would be against. Any plan they would offer would be a placebo at best. We got people making arguments to invade other countries and forcing them to clean up their climate issues instead of forcing the US government to do the same.
If any plan moderates and conservatives are going to offer going to be means-tested and killed off like you said, then does it matter that they'll be against it?
Like Elfforkusu, Helio, and others in this have said, we cannot win by capitulating our stance on this. You stand on your square and force the issue until people come around. We've gone though decades of celebrating bipartianship when all that really meant was stagnation and the continuous slide to the right.
The idea of what is unrealistic can change though and one of the way it can change is by people advocating for it and forcing other people who have never considered it to have that conversation. We've already seen this happen with things like Medicare for all.
The socialists in America took too long to get their act together to dismantle capitalism, that window has passed. You can't both successfully combat climate change and dismantle capitalism at the same time, and I'm unconvinced American socialists can achieve either in their current state.
That "cost" is what's going to get what needs to be done to save that burning building, ignoring it is doing nothing while watching that building burn down. Appealing to emotion has a lousy track record of getting bills through congress, you'll get me to agree with you but not the politicians you want to do what's required. People are dying right now, so stop trying to waste this time looking for a gift from the gods and work with what we have to get it passed congress. Executive orders won't save us with this, and that'a assuming Brnie wins,.
That's not my argument. My disagreeing with you isn't about doing x task, it's about how to do it and what's realistic. You don't go up to your boss and expect to get paid a million when you don't have leverage - Bernie not only hasn't got this leverage, he's in a situation where asking for a raise (to use this metaphor) is impossible given how the company he's working in is structured. This isn't a simple ask here, he wants the moon and the stars delivered to him on a yellow cushion. And I say that agreeing with many things he does, but sadly we don't live in a country where agreeing with something politically means it's easy to get through congress. And it's only gotten worse since Trump got elected.
Politics is negotiation, except negotiation is pointless without the leverage required and if what's being asked isn't remotely possible within how congress is structured. Look at what happened during and after the ACA got passed, and that's a bill which was easier to pass than this.
Then we're doomed, since going big in congress is going to kill that bill. This is congress, compromise is the name of the game.
Congress does, and the powers limited by the government and the various elements within the Democratic and Republican parties.
Not according to me, according to congress. I'm going to ask you a question, how many leftist politicians do you think is in congress right now? By my count it's 7 in the House, and 1 in the senate.
As for why? Many are moderate or conservative in nature, many serve in moderate and conservative districts, they need to work and for wealthy donors and businesses, they need to work with leadership in their parties and so on. Bernie needs to get all these people on board or he's got nothing. And there's the Supreme Court to account for, too. Do you trust the current Supreme Court to protect Bernie's bill as it is if the GOP will try to repeal it? They'll done this dance before with the ACA they won't hesitate to do it with a bill about climate change. Bernie had better have good answers for all this or we're back to square one on this subject.
This sidesteps what were talking about, which is what cases congress itself. That's the biggest obstacle to Bernie with his bills is the structure of congress itself, and the people who were elected that need to vote on his bill. This argument is not going to be what needs to be done to get them to switch, they're politicians, not average citizens.
That works in activism, that's a death knell in congress. When bipartisanship dies, whatever chances this bill had of passing died with it. It's the bedrock of politics, its death is not something to be celebrated. Republicans want it dead because they want to tear this country down, the left want a country that governs properly and you're going to find politicians having their arms tied behind their back without bipartisanship. Your argument ignores the fact what you want was never how the American government was made to do, or this would have been done decades ago.
The ACA might be the most instructive example. The Democrats preemptively compromised themselves into a Republican plan ("personal responsibility! Romneycare!"), and it still was eroded. Go center and you end up center-right. Go left.
Bernie is the man, but I'm afraid it'll be instead that US will be remembered for being the peak of human self destructiveness. For as long as anyone will be around to remember.
No, that's not the issue.
The issue is Sanders has presented a bad climate change proposal involving the energy sector regarding emissions reductions.
Let's just ignore the fact that 100% renewable is not possible in the presented timeframe, I'm going to work with the logic that it is possible (it's not).
The issue with a 100% renewable goal, especially when you look at the current energy production landscape in America, is that as of current, once you get into the 30%/40% penetration of renewables, you start running into issues with cost effective storage during peak production, variability and interaction with other electrical generation. Now, this can be fixed and worked around with a major investment in a modern grid and dumping a few trillion into bringing down the cost of storage, which is good and what any plan regarding the nations electrical generation needs.
The issue is, let's say we can start penetrating 50%, 60% renewable rates in terms of generation. Good, now you're about to deal with the really fucking hard part.
The cost for more renewables fitting into the grid increases exponentially because of storage issues and when renewable energy is generated through your average day. The cost of each new percent increases the cost of the next percent because you're simply tapping into generation that's already saturated to the max with storage that is still likely not going to be cost effective to offset the requirements needed for the new renewable production being installed.
Does that mean "you do nothing". Well, no, nobody said that. That just means that you look at what all the current research is showing in terms of cost effectiveness and the current statistics that states with high renewable shares are currently facing in terms of costs for installing more renewables and see what you should do to avoid such pitfalls.
Which is why, while you don't need nuclear to be the majority of your energy production, putting a fucking ban on new nuclear plants is a horrible climate change policy.
We have viable pathways for radically transforming our energy infrastructure within the next 15 years. With current technology, with no major investment into storage, we can very easily get a nation wide energy share of ~40% renewables from very basic investments and public policy.
But a good, driven climate plan can likely get us to 60% renewable share before the big issues of storage come into play, and that's even with massive investments into storage solutions. With a majority of energy production being renewable, you then focus on how you offset the 40% non-renewable?
If you're at 60% renewable, then the question is, what did you just remove?
Note, this is pen on the back of the napkin math, but I'm just trying to make a point of why 100% renewable isn't ideal in terms of emissions reduction policy.
Well, likely coal is dead. We can wipe that off and say you just added ~30% to non-hydro renewables (And I'm just going to use current figures of energy shares instead of trying to extrapolate what percent of natural gas/nuclear will be in the future).
Now you're at 40% Renewable, ~35% Natural Gas, 20% Nuclear. Killing coal and replacing it with renewables is probably the easiest thing you can do in terms of climate policy. Coal plants are old, they are going to be closer to their end of life date than new natural gas plants (which is why natural gas is murdering coal, because plants are being converted from coal to natural gas).
Now let's say you start installing some new nuclear production into the mix, enough to get you to ~30% of national energy needs from nuclear. You're not going to want to cut into your renewable generation, and with the rapid installation of storage for your non-hydro renewables you can start cutting into your natural gas generation. It takes around 5 years of actual construction time to build nuclear plants, so you're going to have basically a decade before you see nuclear generation increase.
So lets say, we invest enough into nuclear to both replace aging plants and enough to get another 10% of electrical generation out of the production pie.
40% Renewable, 30% Nuclear, 23% natural gas, 7% misc
Now, that doesn't look as ambition as 100% renewable fun time, but you just fucking murdered coal generation and made natural gas the highest fossil fuel electrical generation production at ~20% of national electrical generation.
That's all done within a decade (give or take a few years), with no major technological breakthrough in storage capacity at likely around ~4/5 trillion in total investment between federal and private investments.
And that's not talking about the gains you will be making in transportation. Much like the Sanders plan, you can and will be dumping massive amount of funds into programs to decarbonize the public and private transportation sector. By the mid 2020's EV's will likely overtake ICEs in annual sales regardless of major policy initiatives, it should be paramount that while there is a rapid decarbonization in the energy sector, the transportation sector has similar efforts being taken place. It will be slower than the energy production because people aren't going to sell their ICE cars years before they want to, but that's a different discussion.
Now, most people are going to say, "well this is bullshit and what about the natural gas". Yea, well like I said, this is what I would say is a far more realistic pathway to emissions reduction that doesn't require any major breakthroughs in technology that currently does not exist at the costs needed to produce 100% renewables, and does not have the infrastructure developed to support it.
By 2030 if you have a 40% Renewable, 30% nuclear, ~20% natural gas, you can start chipping away at the natural gas over the next decade with the aforementioned "really hard part" of increasing renewable energy share past the 40% threshold. A big issue with renewables, even at lower penetration levels, is once you start maxing out their capacity factor you have a very "rigid" grid that isn't flexible or conducive to to nuclear energy and will also increase the costs of natural gas production from needing to constantly ramp up/down to match variable energy production. That's where storage comes in because it gives you flexibility. This can also be a test pilot for carbon capture as well for a portion of our natural gas plants that are still operating in the 2030's.
The great thing about renewables is their costs will drop off a cliff in the future. In the mid 2050's solar and wind will likely be close to "free" energy, with the costs being storage. This is long term, but I would not be shocked if nations start planning on producing carbon capture and hooking it up to isolated renewable generation that can produce energy at no need for storage and sucking carbon out of the atmosphere whenever there is enough power to do so.
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Going left would have left us with nothing. That's what you're proposing, when a Republican plan got that reception. Republicans didn't try to neuter the ACA because it didn't didn't go further left, they're right wingers.
So I want to preface this post by mentioning that recently I have been in direct communication with a few scientists in various fields pertaining to climate change, including Mark Jacobson (and yes, he and other experts have been made aware of this thread). Mark in particular has been quite gracious in answering my questions, not just about his critics (some of whom, as I understand, are paid by the Trump administration to oppose climate action, as evidenced here) but about the challenges we face with addressing climate change by transitioning to 100% renewable energy in a reasonable time-frame. I found his insights illuminating and look forward to doing what I can to increase science literacy regarding the potential of renewable energy technologies.
For now, I'd like to focus on the feasibility of relying solely on renewable energy for power in the future. There is sufficient review of scientific literature to suggest that not only is 100% globally renewable energy possible, but it is arguably more feasible than nuclear-mixed solutions when you factor in longer time-scales. Here are some excerpts from T.W. Brown et al's response (and before anyone asks, Jacobson had no part in publishing their response) to 'Burden of proof: A comprehensive review of the feasibility of 100% renewable-electricity systems', formatted for improved readability and accessibility:
_________________________________________________________________________________________________________________________________________________________________________________
Highlights
• We respond to a recent article that is critical of the feasibility of 100% renewable-electricity systems.
• Based on a literature review we show that none of the issues raised in the article are critical for feasibility or viability.
• Each issue can be addressed at low economic cost, while not affecting the main conclusions of the reviewed studies.
• We highlight methodological problems with the choice and evaluation of the feasibility criteria.
• We provide further evidence for the feasibility and viability of renewables-based systems.
1. Introduction
There is a broad scientific consensus that anthropogenic greenhouse gas emissionsshould be rapidly reduced in the coming decades in order to avoid catastrophic global warming [1]. To reach this goal, many scientific studies ([2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35], [36], [37], [38], [39], [40], [41], [42], [43], [44], [45], [46], [47], [48], [49], [50], [51], [52], [53], [54], [55], [56], [57], [58], [59], [60], [61] are discussed in this article) have examined the potential to replace fossil fuel energysources with renewable energy. Since wind and solar power dominate the expandable potentials of renewable energy [3], a primary focus for studies with high shares of renewables is the need to balance the variability of these energy sources in time and space against the demand for energy services.
The studies that examine scenarios with very high shares of renewable energy have attracted a critical response from some quarters, particularly given that high targets for renewable energy are now part of government policy in many countries [62], [63]. Critics have challenged studies for purportedly not taking sufficient account of: the variability of wind and solar [64], [65], the scaleability of some storage technologies [66], all aspects of system costs [64], [65], resource constraints [67], [68], social acceptance constraints [68], energy consumption beyond the electricity sector [68], limits to the rate of change of the energy intensity of the economy [68] and limits on capacity deployment rates [69], [68]. Many of these criticisms have been rebutted either directly [70], [71], [72] or are addressed elsewhere in the literature, as we shall see in the following sections.
...
In this response article we argue that the authors' chosen feasibility criteria may in some cases be important, but that they are all easily addressed both at a technical level and economically at low cost. We therefore conclude that their feasibility criteria are not useful and do not affect the conclusions of the reviewed studies. Furthermore, we introduce additional, more relevant feasibility criteria, which renewable energy scenarios fulfil, but according to which nuclear power, which the authors have evaluated positively elsewhere [74], [75], [76], fails to demonstrate adequate feasibility.
2. Feasibility versus viability
Early in their methods section, the authors define feasibility to mean that something is technically possible in the world of physics 'with current or near-current technology'. They distinguish feasibility from socio-economic viability, which they define to mean whether it is possible within environmental and social constraints and at a reasonable cost. While there is no widely-accepted definition of feasibility [77], other studies typically include economic feasibility in their definition [78], [79], [80], [81], [82], while others also consider social and political constraints [83], [68]. For the purposes of this response article, we will keep to the authors' definitions of feasibility and viability.
One reason that few studies focus on such a narrow technical definition of feasibility is that, as we will show in the sections below, there are solutions using today's technology for all the feasibility issues raised by the authors. The more interesting question, which is where most studies rightly focus, is how to reach a high share of renewables in the most cost-effective manner, while respecting environmental, social and political constraints. In other words, viability is where the real debate should take place. For this reason, in this paper we will assess both the feasibility and the viability of renewables-based energy systems.
Furthermore, despite their declared focus on feasibility, the authors frequently mistake viability for feasibility. Examples related to their feasibility criteria are examined in more detail below, but even in the discussion of specific model results there is confusion. The authors frequently quote from cost-optimisation studies that 'require' certain investments. For example they state that [84] 'required 100 GWe of nuclear generation and 461 GWe of gas' and [85] 'require long-distance interconnector capacities that are 5.7 times larger than current capacities'. Optimisation models find the most cost-effective (i.e. viable) solutions within technical constraints (i.e. the feasible space). An optimisation result is not necessarily the only feasible one; there may be many other solutions that simply cost more. More analysis is needed to find out whether an investment decision is 'required' for feasibility or simply the most cost-effective solution of many. For example, the 100 GWe of nuclear in [84] is fixed even before the optimisation, based on existing nuclear facilities, and is therefore not the result of a feasibility study. However, the authors do acknowledge that their transmission feasibility criteria 'could arguably be regarded as more a matter of viability than feasibility'.
Finally, when assessing economic viability, it is important to keep a sense of perspective on costs. If Europe is taken as an example, Europe pays around 300–400 billion € for its electricity annually.1 EU GDP in 2016 was 14.8 trillion € [86]. Expected electricity network expansion costs in Europe of 80 billion € until 2030 [89] may sound high, but once these costs are annualised (e.g. to 8 billion €/a), it amounts to only 2% of total spending on electricity, or 0.003 €/kWh.
3. Feasibility criteria
...
We observe that the authors' choice of criteria, the weighting given to them and some of the scoring against the criteria are somewhat arbitrary. As argued below, there are other criteria that the authors did not use in their rating that have a stronger impact on feasibility (such as resource constraints and technological maturity); based on the literature review below, the authors' criteria would receive a much lower weighting than these other, more important criteria; and the scoring of some of the criteria, particularly for primary energy, transmission and ancillary services, seems coarse and subjective. Regarding the scoring, for demand projections the studies are compared with a spectrum from the mainstream literature, but no uncertainty bound is given, just a binary score; for transmission there is no nuance between studies that use blanket costs for transmission, or only consider cross-border capacity, or distribution as well as transmission networks; and no weighting is given to the importance of the different ancillary services.
...
3.1. Their feasibility criterion 1: Demand projections
The authors criticise some of the studies for not using plausible projections for future electricity and total energy demand. In particular, they claim that reducing global primary energy consumption demand is not consistent with projected population growth and development goals in countries where energy demand is currently low.
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However, the authors chose to focus on primary energy, for which the situation is more complicated, and it is certainly plausible to decouple primary energy consumption growth from meeting the planet's energy needs. Many countries have already decoupled primary energy supply from economic growth; Denmark has 30 years of proven history in reducing the energy intensity of its economy [92].
There are at least three points here: i) primary energy consumption automatically goes down when switching from fossil fuels to wind, solar and hydroelectricity, because they have no conversion losses according to the usual definition of primary energy; ii) living standards can be maintained while increasing energy efficiency; iii) renewables-based systems avoid the significant energy usage of mining, transporting and refining fossil fuels and uranium.
Fig. 1 illustrates how primary energy consumption can decrease by switching to renewable energy sources, with no change in the energy services (blue) delivered. Using the 'physical energy accounting method' used by the IEA, OECD, Eurostat and others, or the 'direct equivalent method' used by the IPCC, the primary energy consumption of fossil fuel power plants corresponds to the heating value, while for wind, solar and hydro the electricity output is counted. This automatically leads to a reduction in the primary energy consumption of the electricity sector when switching to wind, solar and hydro, because they have no conversion losses (by this definition).
Fig. 1. Primary energy consumption (grey and green) versus useful energy services (blue) in today's versus tomorrow's energy system.
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If statistics from the European Union in 2015 [101] are taken as an example, taking the steps outlined in Fig. 1 would reduce total primary energy consumption by 49%2without any change in the delivered energy services. (Final energy consumption would also drop by 33%.) A reduction of total primary energy of 49% would allow a near doubling of energy service provision before primary energy consumption started to increase. This is even before efficiency measures and the consumption from fuel processing are taken into account.
The primary energy accounting of different energy sources presented in this example is already enough to explain the discrepancies between the scenarios plotted in Fig. 1 of [73], where the median of non-NGO global primary energy consumption increases by around 50% between 2015 and 2050, while the NGOs Greenpeace and WWF see light reductions.
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The authors chose to concentrate on primary energy consumption, but for renewables, as argued above, it can be a misleading metric (see also the discussion in [96]). The definitions of both primary and final energy are suited for a world based on fossil fuels. What really matters is meeting people's energy needs (the blue boxes in Fig. 1) while also reducing greenhouse gas emissions.
Next we address energy efficiency that goes beyond just switching fuel source. There is plenty of scope to maintain living standards while reducing energy consumption: improved building insulation and design to reduce heating and cooling demand, more efficient electronic devices, efficient processes in industry, better urban designto lower transport demand, more public transport and reductions in the highest-emission behaviour. These efficiency measures are feasible, but it is not clear that they will all be socio-economically viable.
One final, critical point: even if future demand is higher than expected, this does not mean that 100% renewable scenarios are infeasible. As discussed in Section 3.6, the global potential for renewable generation is several factors higher than any demand forecasts. There is plenty of room for error if forecasts prove to underestimate demand growth: an investigation into the United States Energy Information Administration's Annual Outlook [106] showed systematic underestimation of total energy demand by an average of 2% per year after controlling for other sources of projection errors; over 35 years this would lead to an underestimate of around factor 2 (assuming other sources of growth are not excessive); reasonable global potentials for renewable energy could generate on average around 620 TW [3], which is a factor 30 higher than business-as-usual forecasts for average global end-use energy demand of 21 TW in 2050 [36].
3.2. Their feasibility criterion 2a: Simulation time resolution
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It is of course important that models have enough time resolution to capture variations in energy demand (e.g. lower electricity consumption at 3 a.m. than at 3 p.m.) and variations in wind and solar generation, so that balancing needs, networks and other flexibility options can be dimensioned correctly. However, the time resolution depends on the area under consideration, since short-term weather fluctuations are not correlated over large distances and therefore balance out. This criterion should rather read 'the time resolution should be appropriate to the size of the area being studied, the weather conditions found there and the research question'. Models for whole countries typically use hourly simulations, and we will argue that this is sufficient for long-term energy system planning.
After all, why do the authors stop at 5 min intervals? For a single wind turbine, a gust of wind could change the feed-in within seconds (the inertia of the rotor stops faster changes). Similarly, a cloud could cover a small solar panel in under a second. Individuals can change their electricity consumption at the flick of a switch.
The reason modelling in this temporal detail is not needed is the statistical smoothing when aggregating over a large area containing many generators and consumers. Many of the studies are looking at the national or sub-national level. By modelling hourly, the majority of the variation of the demand and variable renewables like wind and solar over these areas is captured; if there is enough flexibility to deal with the largest hourly variations, there is enough to deal with any intra-hour imbalance. Fig. 2 shows correlations in variations (i.e. the differences between consecutive production values) in wind generation at different time and spatial scales.3 Changes within 5 min are uncorrelated above 25 km and therefore smooth out in the aggregation. Further analysis of sub-hourly wind variations over large areas can be found in [108], [109].
Fig. 2. Correlation of variations in wind for different time scales in Germany.
For solar photovoltaics (PV) the picture is similar at shorter time scales: changes at the 5-min level due to cloud movements are not correlated over large areas. However, at 30 min to 1 h there are correlated changes due to the position of the sun in the sky or the passage of large-scale weather fronts. The decrease of PV output in the evening can be captured at one-hour resolution and there are plenty of feasible technologies available for matching that ramping profile: flexible open-cycle gas turbines can ramp up within 5–10 min, hydroelectric plants can ramp within minutes or less, while battery storage and demand management can act within milliseconds. For ramping down, solar and wind units can curtail their output within seconds.
The engineering literature on sub-hourly modelling confirms these considerations. Several studies consider the island of Ireland, which is particularly challenging since it is an isolated synchronous area, is only 275 km wide and has a high penetration of wind. One power system study for Ireland with high share of wind power [112] varied temporal resolution between 60 min and 5 min intervals, and found that the 5 min simulation results gave system costs just 1% higher than hourly simulation results; however, unit commitment constraints and higher ramping and cycling rates could be problematic for older thermal units (but not for the modern, flexible equipment outlined above). Similarly, [113], [114] see not feasibility problems at sub-hourly time resolutions, but a higher value for flexible generation and storage, which can act to avoid cycling stress on older thermal plants. In [115] the difference between hourly and 15-min simulations in small district heating networks with high levels of wind power penetration was considered and it was found that 'the differences in power generation are small' and 'there is [no] need for higher resolution modelling'.
To summarise, since at large spatial scales the variations in aggregated load, wind and solar time series are statistically smoothed out, none of the large-scale model results change significantly when going from hourly resolution down to 5-min simulations. Hourly modelling will capture the biggest variations and is therefore adequate to dimension flexibility requirements. (Reserve power and the behaviour of the system in the seconds after faults are discussed separately in Section 3.5.) Sub-hourly modelling may be necessary for smaller areas with older, inflexible thermal power plants, but since flexible peaking plant and storage are economically favoured in highly renewable systems, sub-hourly modelling is less important in the long-term.
Simulations with intervals longer than one hour should be treated carefully, depending on the research question [116].
3.3. Their feasibility criterion 2b: Extreme climatic events
The authors reserve a point for studies that include rare climatic events, such as long periods of low sun and wind, or years when drought impacts the production of hydroelectricity.
Periods of low sun and wind in the winter longer than a few days can be met, where available, by hydroelectricity, dispatchable biomass, demand response, imports, medium-term storage, synthetic gas from power-to-gas facilities (the feasibility of each of these is discussed separately below) or, in the worst case, by fossil fuels.
From a feasibility point of view, even in the worst possible case that enough dispatchable capacity were maintained to cover the peak load, this does not invalidate these scenarios. The authors write "ensuring stable supply and reliability against all plausible outcomes…will raise costs and complexity". Yet again, a feasibility criterion has become a viability criterion.
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A recent study of seven different weather years (2006–2012), including extreme weather events, in Europe for a scenario with a 95% CO2 reduction compared to 1990 in electricity, heating and transport [119] came to similar conclusions. The extreme events do not affect all countries simultaneously so, for example, Germany can cover extreme events by importing power from other countries. If for political reasons each country is required to cover its peak load on a national basis, the extra costs for capacity are at most 3% of the total system costs.
For systems that rely on hydroelectricity, the authors are right to point out that studies should be careful to include drier years in their simulations. Beyond the examples they cite, Brazil's hydroelectric production has been restricted over the last couple of years due to drought, and there are periodic drier years in Ethiopia, Kenya and Scandinavia, where in the latter inflow can drop to 30% below the average [108].
However, in most countries, the scenarios rely on wind and solar energy, and here the dispatchable power capacity of the hydro is arguably just as important in balancing wind and solar as the total yearly energy contribution, particularly if pumping can be used to stock up the hydro reservoirs in times of wind and solar abundance [7], [54].
Note that nuclear also suffers from planned and unplanned outages, which are exacerbated during droughts and heatwaves, when the water supplies for river-cooled plants are either absent or too warm to provide sufficient cooling [120]. This problem is likely to intensify given rising demand for water resources and climate change [120].
3.4. Their feasibility criterion 3: Transmission and distribution grids
The authors criticise many of the studies for not providing simulations of the transmission (i.e. high voltage long-distance grid) and distribution (i.e. lower voltage distribution from transmission substations to consumers) grids. Again, this is important, but not as important as the authors assume. Feasibility is not the issue (there are no technical restrictions on expanding the grid), but there are socio-economic considerations. Many studies that do not model the grid, do include blanket costs for grid expansion (e.g. from surveys such as [121], [122], [123]).
On a cost basis, the grid is not decisive either: additional grid costs tend to be a small fraction of total electricity system costs (examples to follow, but typically around 10–15% of total system costs in Europe [124], [125], [126], [127], [21], [42], [123]), and optimal grid layouts tend to follow the cheapest generation, so ignoring the grid is a reasonable first order approximation. Where it can be a problem is if public acceptance problems prevent the expansion of overhead transmission lines, in which case the power lines have to be put underground (typically 3–8 times more expensive than overhead lines) or electricity has to be generated more locally (which can drive up costs and may require more storage to balance renewables). Public acceptance problems affect cost, i.e. economic viability, not feasibility.
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A study by Imperial College, NERA and DNV GL for the European electricity system to 2030 [124] examined the consequences for both the transmission and distribution grid of renewable energy penetration up to 68% (in their Scenario 1). For total annual system costs of 232 billion €/a in their Scenario 1, 4 billion €/a is assigned to the costs of additional transmission grid investments and 18 billion €/a to the distribution grid. If there is a greater reliance on decentralised generation (Scenario 1(a)-DG), additional distribution grid costs could rise to 24 billion €/a.
This shows a typical rule of thumb: additional grid costs are around 10–15% of total system costs. But this case considered only 68% renewables.
The distribution grid study of 100% renewables in the German federal state of Rhineland-Palatinate (RLP) [125] also clearly demonstrates that the costs of generation dwarf the grid costs. Additional grid investments vary between 10% and 15% of the total costs of new generation, depending on how smart the system is. Again, distribution upgrade costs dominate transmission costs.
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The authors quote studies that look at optimal cross-border transmission capacity in Europe at very high shares of renewables, which show an expansion of 4–6 times today's capacities [85], [129]. It is worth pointing out that these studies look at the international interconnectors, not the full transmission grid, which includes the transmission lines within each country. The interconnectors are historically weak compared to national grids4 and restricted by poor market design and operation [130]; if a similar methodology to [85], [129] is applied to a more detailed grid model with nodal pricing, the expansion is only between 25% and 50% more than today's capacity [42]. Furthermore, cost-optimal does not necessarily mean socially viable; there are solutions with lower grid expansion and hence higher public acceptance, but higher storage costs to balance renewables locally [42].
3.5. Their feasibility criterion 4: Ancillary services
Finally, we come to ancillary services. Ancillary services are additional services that network operators need to stabilise and secure the electricity system. They are mostly provided by conventional dispatchable generators today. Ancillary services include reserve power for balancing supply and demand in the short term, rotating inertia to stabilise the frequency in the very short term, synchronising torque to keep all generators rotating at the same frequency, voltage support through reactive power provision, short circuit current to trip protection devices during a fault, and the ability to restart the system in the event of a total system blackout (known as 'black-starting'). The authors raise concerns that many studies do not consider the provision of these ancillary services, particularly for voltage and frequency control. Again, these concerns are overblown: ancillary services are important, but they can be provided with established technologies (including wind and solar plants), and the cost to provide them is second order compared to the costs of energy generation.
We consider fault current, voltage support and inertia first. These services are mostly provided today by synchronous generators, whereas most new wind, solar PV and storage units are coupled to the grid with inverters, which have no inherent inertia and low fault current, but can control voltage with both active and reactive power.
From a feasibility point of view, synchronous compensators could be placed throughout the network and the problem is solved, although this is not as cost effective as other solutions. Synchronous compensators (SC), also called synchronous condensers, are essentially synchronous generators without a prime mover to provide active power. This means they can provide all the ancillary services of conventional generators except those requiring active power, i.e. they can provide fault current, inertia and voltage support just like a synchronous generator. Active power is then provided by renewable generators and storage devices.
In fact, existing generators can be retrofitted to be SC, as happened to the nuclear power plant in Biblis, Germany [131], or to switch between generation mode and SC mode; extra mass can be added with a clutch if more inertia is needed (SC have an inertia time constant of 1–2 s [132], [133], compared to typical conventional generators with around 6 s). SC are a tried-and-tested technology and have been installed recently in Germany [134], Denmark, Norway, Brazil, New Zealand and California [135]. They are also used in Tasmania [136], where 'Hydro Tasmania, TasNetworks and AEMO have implemented many successful initiatives that help to manage and maintain the security of a power system that has a high penetration of asynchronous energy sources…Some solutions implemented in Tasmania have been relatively low cost and without the need for significant capital investment' [136]. In Denmark, newly-installed synchronous compensators along with exchange capacity with its neighbours allow the power system to operate without any large central power stations at all [137].
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Next, we consider balancing reserves. Balancing power can be provided by traditional providers, battery systems, fast-acting demand-side-management or by wind and solar generators (upward reserves are provided by variable renewable plants by operating them below their available power, called 'delta' control). There is a wide literature assessing requirements for balancing power with high shares of renewables. In a study for Germany in 2030 with 65 GW PV and 81 GW wind (52% renewable energy share), no need is seen for additional primary reserve, with at most a doubling of the need for other types of reserves [161]. It is a similar story in the 100% renewable scenario for Germany of Kombikraftwerk 2 [162]. (Maintaining reserves in Germany cost 315.9 million € in 2015 [163].) There is no feasibility problem here either.
Another ancillary service the authors mention is black-start capability. This is the ability to restart the electricity system in the case of a total blackout. Most thermal power stations consume electricity when starting up (e.g. powering pumps, fans and other auxiliary equipment), so special provisions are needed when black-starting the system, by making sure there are generators which can start without an electricity supply. Typically system operators use hydroelectric plants (which can generate as soon as the sluice gate is opened), diesel generators or battery systems, which can then start a gas turbine, which can then start other power plants (for example). Maintaining conventional capacity for black-start is inexpensive compared to system costs, as shown in Section 3.3; in a study for Germany in 2030 [161] with 52% renewables, no additional measures for black-starting were deemed necessary, contrary to the interpretation in [73]; finally, decentralised renewable generators and storage could also participate in black-starting the system in future [162]. The use of battery storage systems to black-start gas turbines has recently been demonstrated in Germany [164] and in a commercial project in California [165].
Nuclear, on the other hand, is a problem for black-starting, since most designs need a power source at all times, regardless of blackout conditions, to circulate coolant in the reactor and prevent meltdown conditions. This will only exacerbate the need for backup generation in a total blackout. Nuclear is sometimes not used to provide primary reserves either, particularly in older designs, because fast changes in output present operational and safety concerns.
3.6. Our feasibility criterion 5: Fuel source that lasts more than a few decades
Here we suggest a feasibility criterion not included on the authors' list: The technology should have a fuel source that can both supply all the world's energy needs (not just electricity, but also transport, heating and industrial demand) and also last more than a couple of decades.
Traditional nuclear plants that use thermal-neutron fission of uranium do not satisfy this feasibility criterion. In 2015 there were 7.6 million tonnes of identified uranium resources commercially recoverable at less than 260 US$/kgU [166].5 From one tonne of natural uranium, a light-water reactor can generate around 40 GWh of electricity.
In 2015, world electricity consumption was around 24,000 TWh/a [168]. Assuming no rise in electricity demand and ignoring non-electric energy consumption such as transport and heating, uranium resources of 7.6 million tonnes will last 13 years. Reprocessing, at higher cost, might extend this by a few more years. Including non-electric energy consumption would more than halve this time.
For renewables, exploitable energy potentials exceed yearly energy demand by several orders of magnitude [169] and, by definition, are not depleted over time. Even taking account of limitations of geography and material resources, the potentials for the expansion of wind, solar and storage exceed demand projections by several factors [3].
As for 'following all paths' and pursuing a mix of renewables and nuclear, they do not mix well: because of their high capital costs, nuclear power plants are most economically viable when operated at full power the whole time, whereas the variability of renewables requires a flexible balancing power fleet [170]. Network expansion can help the penetration of both renewables and inflexible plant [171], but this would create further pressure for grid expansion, which is already pushing against social limits in some regions.
This feasibility criterion is not met by standard nuclear reactors, but could be met in theory by breeder reactors and fusion power. This brings us to our next feasibility criterion.
3.7. Our feasibility criterion 6: Should not rely on unproven technologies
Here is another feasibility criterion that is not included on the authors' list: Scenarios should not rely on unproven technologies. We are not suggesting that we should discontinue research into new technologies, rather that when planning for the future, we should be cautious and assume that not every new technology will reach technical and commercial maturity.
The technologies required for renewable scenarios are not just tried-and-tested, but also proven at a large scale. Wind, solar, hydro and biomass all have capacity in the hundreds of GWs worldwide [63]. The necessary expansion of the grid and ancillary services can deploy existing technology (see 3.4 Their feasibility criterion 3: Transmission and distribution grids, 3.5 Their feasibility criterion 4: Ancillary services). Heat pumps are used widely [172]. Battery storage, contrary to the authors' paper, is a proven technology already implemented in billions of devices worldwide (including a utility-scale 100 MW plant in South Australia [173] and 700 MW of utility-scale batteries in the United States at the end of 2017 [174]). Compressed air energy storage, thermal storage, gas storage, hydrogen electrolysis, methanation and fuel cells are all decades-old technologies that are well understood. (See Section 4.1for more on the feasibility of storage technologies.)
On the nuclear side, for the coming decades when uranium for thermal-neutron reactors would run out, we have breeder reactors, which can breed more fissile material from natural uranium or thorium, or fusion power.
Breeder reactors are technically immature (with a technology readiness levelbetween 3 and 5 depending on the design [175]), more costly than light-water reactors, unreliable, potentially unsafe and they pose serious proliferation risks [176]. Most fast-neutron breeder reactors rely on sodium as a coolant, and since sodium burns in air and water, it makes refueling and repair difficult. This has led to serious accidents in fast breeder reactors, such as the major sodium fire at the Monju plant in 1995. Some experts consider fast breeders to have already failed as a technology option [176], [177]. The burden of proof is on the nuclear industry to demonstrate that breeder reactors are a safe and commercially competitive technology.
Fusion power is even further from demonstrating technical feasibility. No fusion plant exists today that can generate more energy than it requires to initiate and sustain fusion. Containment materials that can withstand the neutronbombardment without generating long-lived nuclear waste are still under development. Even advocates of fusion do not expect the first commercial plant to go online before 2050 [178]. Even if it proves to be feasible and cost-effective (which is not clear at this point), ramping up to a high worldwide penetration will take decades more. That is too late to tackle global warming [179].
4. Other issues
In this section we address other issues raised by the authors of [73] during their discussion of their feasibility criteria.
4.1. Feasibility of storage technologies
The authors write "widespread storage of energy using a range of technologies (most of which - beyond pumped hydro - are unproven at large scales, either technologically and/or economically)".
Regarding battery storage, it is clear that there is the potential to exploit established lithium ion technology at scale and at low cost [180], [181], [182]. The technology is already widely established in electronic devices and increasingly in battery electric vehicles, which will in future provide a regular and cheap source of second-life stationary batteries. A utility-scale 100 MW plant was installed in the South Australian grid in 2017 [173] and there was already 700 MW of utility-scale batteries in the United States at the end of 2017 [174]. Further assessments of the potential for lithium ion batteries can be found in [3]. Costs are falling so fast that hybrid PV-battery systems are already or soon will be competitive with conventional systems in areas with good solar resources [183], [184].
Many other electricity storage devices have been not just demonstrated but already commercialised [185], including large-scale compressed air energy storage. Technologies that convert electricity to gas, by electrolysing hydrogen with the possibility of later methanation, are already being demonstrated at megawatt scale [186], [187]. Hydrogen could either be fed into the gas network to a certain fraction, used in fuel cell vehicles, converted to other synthetic fuels, or converted back into electricity for the grid. Fuel cells are already manufactured at gigawatt scale, with 480 MW installed in 2016 [188]. By using the process heat from methanation to cover the heat consumption of electrolysis, total efficiency for power-to-methane of 76% has recently been demonstrated in a freight-container-sized pilot project, with 80% efficiency in sight [189].
Moreover, in a holistic, cross-sectoral energy systems approach that goes beyond electricity to integrate all thermal, transport and industrial demand, it is possible to identify renewable energy systems in which all storage is based on low-cost well-proven technologies, such as thermal, gas and liquid storage, all of which are cheaper than electricity storage [190]. These sectors also provide significant deferrable demand, which further helps to integrate variable renewable energy [191], [29], [46]. Storage capacity for natural gas in the European Union is 1075 TWh as of mid 2017 [192].
4.2. Feasibility of biomass
The authors criticise a few studies for their over-reliance on biomass, such as one for Denmark [10] and one for Ireland [11]. There are legitimate concerns about the availability of fuel crops, environmental damage, biodiversity loss and competition with food crops [193]. More recent studies, including some by the same researchers, conduct detailed potential assessments for biomass and/or restrict biomass usage to agricultural residues and waste [194], [98], [195], [22]. Other studies are even more conservative (or concerned about air pollution from combustion products [87]) and exclude biomass altogether [41], [3], [7], [36], [46], while still reaching feasible and cost-effective energy systems.
4.3. Feasibility of carbon capture
Capturing carbon dioxide from industrial processes, power plants or directly from the air could also contribute to mitigating net greenhouse gas emissions. The captured carbon dioxide can then be used in industry (e.g. in greenhouses or in the production of synthetic fuels) or sequestered (e.g. underground). While some of the individual components have been demonstrated at commercial scale, hurdles [196], [197], [198] include cost, technical feasibility of long-term sequestration without leakage, viability for some concepts (such as direct air capture (DAC), the lowest cost version of which is rated at Technology Readiness Level (TRL) 3–5 [199]), other air pollutants from combustion and imperfect capture when capturing from power plants, lower energy efficiency, regulatory issues, public acceptance of sequestration facilities [200] and systems integration.
Studies at high time resolution that have combined renewables and power plants with carbon capture and sequestration (CCS) suggest that CCS is not cost effective because of high capital costs and low utilisation [201]. However, DAC may be promising for the production of synthetic fuels [29], [202], [203] and is attractive because of its locational flexibility and minimal water consumption [204], [205]. Negative emissions technologies (NET), which include DAC, bioenergy with CCS, enhanced weathering, ocean fertilisation, afforestation and reforestation, may also be necessary to meet the goals of the Paris climate accord [206], [207], [208], [209]. Relying on NET presents risks given their technical immaturity, so further research and development of these technologies is required [206], [210], [211], [212].
4.4. Viability of renewable energy systems
With regard to social viability, there are high levels of public support for renewable energy. In a survey of European Union citizens for the European Commission in 2017, 89% thought it was important for their national government to set targets to increase renewable energy use by 2030 [213]. A 2017 survey of the citizens of 13 countries from across the globe found that 82% believe it is important to create a world fully powered by renewable energy [214]. A 2016 compilation of surveys from leading industrialised countries showed support for renewables in most cases to be well over 80% [215]. Concerns have been raised primarily regarding the public acceptance of onshore wind turbines and overhead transmission lines. Repeated studies have shown that public acceptance of onshore wind can be increased if local communities are engaged early in the planning process, if their concerns are addressed and if they are given a stake in the project outcome [216], [217], [218]. Where onshore wind is not socially viable, there are system solutions with higher shares of offshore wind and solar energy, but they may cost fractionally more [219]. The picture is similar with overhead transmission lines: more participatory governance early in the planning stages and local involvement if the project is built can increase public acceptance [220], [221]. Again, if overhead transmission is not viable, there are system solutions with more storage and underground cables, but they are more expensive [42]. The use of open data and open model software can help to improve transparency [222], [223], [224].
Next we turn to the economic viability of bulk energy generation from renewable sources. On the basis of levelised cost, onshore wind, offshore wind, solar PV, hydroelectricity and biomass are already either in the range of current fossil fuelgeneration or lower cost [225]. Levelised cost is only a coarse measure [226], since it does not take account of variability, which is why integration studies typically consider total system costs in models with high spatial and temporal resolution. Despite often using conservative cost assumptions, integration studies repeatedly show that renewables-based systems are possible with costs that are comparable or lower than conventional fossil-fuel-based systems [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35], [36], [37], [38], [39], [40], [41], [42], [43], [44], [45], [46], [47], [48], [49], [50], [51], [52], [53], [54], [55], [56], [57], [58], [59], [60], [61], even before aspects such as climate impact and health outcomes are considered.
For example, focusing on results of our own research, a global switch to 100% renewable electricity by 2050 would see a drop in average system cost from 70 €/MWh in 2015 to 52 €/MWh in 2050 [35]. This study modelled the electricity system at hourly resolution for an entire year for 145 regions of the world. Considering all energy sectors in Europe, costs in a 100% renewable energy scenariowould be only 10% higher than a business-as-usual scenario for 2050 [22].
4.5. Viability of nuclear power
Following the authors, we have focused above on the technical feasibility of nuclear. For discussions of the socio-economic viability of nuclear power, i.e. the cost, safety, decomissioning, waste disposal, public acceptance, terrorism and nuclear-weapons-proliferation issues resulting from current designs, see for example [227], [3], [167], [228].
4.6. Other studies of 100% renewable systems
At the time the authors submitted their article there were many other studies of 100% or near-100% renewable systems that the authors did not review. Most studies were simulated with an hourly resolution and many modelled the transmission grid, with examples covering the globe [14], [15], North-East Asia [16], the Association of South-East Asian Nations (ASEAN) [17], Europe and its neighbours [18], Europe [19], [20], [21], [22], [23], South-East Europe [24], the Americas [25], China [26], the United States [27], Finland [28], Denmark [29], Germany [30], Ireland [31], Portugal [32] and Berlin-Brandenburg in Germany [33].
Since then other 100% studies have considered the globe [34], [35], [36], [37], Asia [38], Southeast Asia and the Pacific Rim [39], Europe [40], [41], [42], [43], [44], [45], [46], South-East Europe [47], South and Central America [48], North America [49], India and its neighbours [50], [51], Australia [52], [53], Brazil [54], Iran [55], Pakistan [56], Saudi Arabia [57], Turkey [58], Ukraine [59] the Canary Islands [60] and the Åland Islands [61].
4.7. Places already at or close to 100% renewables
The authors state that the only developed nation with 100% renewable electricity is Iceland. This statement ignores countries which come close to 100% and smaller island systems which are already at 100% (on islands the integration of renewables is harder, because they cannot rely on their neighbours for energy trading or frequency stability), which the authors of [73] chose to exclude from their study.
Countries which are close to 100% renewable electricity include Paraguay (99%), Norway (97%), Uruguay (95%), Costa Rica (93%), Brazil (76%) and Canada (62%) [146]. Regions within countries which are at or above 100% include Mecklenburg-Vorpommern in Germany, Schleswig-Hostein in Germany, South Island in New Zealand, Orkney in Scotland and Samsø along with many other parts of Denmark.
This list mostly contains examples where there is sufficient synchronous generation to stabilise the grid, either from hydroelectricity, geothermal or biomass, or an alternating current connection to a neighbour. There are also purely inverter-based systems on islands in the South Pacific (Tokelau [229] and an island in American Samoa) which have solar plus battery systems. We could also include here any residential solar plus battery off-grid systems.
Another relevant example is the German offshore collector grids in the North Sea, which only have inverter-based generators and consumption. Inverter-interfaced wind turbines are connected with an alternating current grid to an AC-DC converter station, which feeds the power onto land through a High Voltage Direct Currentcable. There is no synchronous machine in the offshore grid to stabilise it, but they work just fine (after teething problems with unwanted harmonics between the inverters).
Off-planet, there is also the International Space Station and other space probes which rely on solar energy.
4.8. South Australian blackout in September 2016
The authors implicitly blame wind generation for the South Australian blackout in September 2016, where some wind turbines disconnected after multiple faults when tornadoes simultaneously damaged two transmission lines (an extreme event). According to the final report by the Australian Energy Market Operator (AEMO) on the incident [230] "Wind turbines successfully rode through grid disturbances. It was the action of a control setting responding to multiple disturbances that led to the Black System. Changes made to turbine control settings shortly after the event [have] removed the risk of recurrence given the same number of disturbances." AEMO still highlights the need for additional frequency control services, which can be provided at low cost, as outlined in Section 3.5.
5. Conclusions
In 'Burden of proof: A comprehensive review of the feasibility of 100% renewable-electricity systems' [73] the authors called into question the feasibility of highly renewable scenarios. To assess a selection of relevant studies, they chose feasibility criteria that are important, but not critical for either the feasibility or viability of the studies. We have shown here that all the issues can be addressed at low economic cost. Worst-case, conservative technology choices (such as dispatchable capacity for the peak load, grid expansion and synchronous compensators for ancillary services) are not only technically feasible, but also have costs which are a magnitude smaller than the total system costs. More cost-effective solutions that use variable renewable generators intelligently are also available. The viability of these solutions justifies the focus of many studies on reducing the main costs of bulk energy generation.
As a result, we conclude that the 100% renewable energy scenarios proposed in the literature are not just feasible, but also viable. As we demonstrated in Section 4.4, 100% renewable systems that meet the energy needs of all citizens at all times are cost-competitive with fossil-fuel-based systems, even before externalities such as global warming, water usage and environmental pollution are taken into account.
The authors claim that a 100% renewable world will require a 're-invention' of the power system; we have shown here that this claim is exaggerated: only a directed evolution of the current system is required to guarantee affordability, reliability and sustainability.
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This article alone makes a very strong case for the feasibility and viability of 100% renewable systems, but the numerous sources and references that support the article's conclusions are what really makes the argument for 100% renewable systems extremely compelling, and worth considering.
At this point, it would appear that the biggest barrier to transitioning to 100% renewable energy is a political one, not a technical one, and to that end, we need to do everything in our power to make sure to tear that barrier down, or we really are well and truly fucked.
For now, I'd like to focus on the feasibility of relying solely on renewable energy for power in the future. There is sufficient review of scientific literature to suggest that not only is 100% globally renewable energy possible, but it is arguably more feasible than nuclear-mixed solutions when you factor in longer time-scales. Here are some excerpts from T.W. Brown et al's response (and before anyone asks, Jacobson had no part in publishing their response) to 'Burden of proof: A comprehensive review of the feasibility of 100% renewable-electricity systems', formatted for improved readability and accessibility:
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Highlights
• We respond to a recent article that is critical of the feasibility of 100% renewable-electricity systems.
• Based on a literature review we show that none of the issues raised in the article are critical for feasibility or viability.
• Each issue can be addressed at low economic cost, while not affecting the main conclusions of the reviewed studies.
• We highlight methodological problems with the choice and evaluation of the feasibility criteria.
• We provide further evidence for the feasibility and viability of renewables-based systems.
1. Introduction
There is a broad scientific consensus that anthropogenic greenhouse gas emissionsshould be rapidly reduced in the coming decades in order to avoid catastrophic global warming [1]. To reach this goal, many scientific studies ([2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35], [36], [37], [38], [39], [40], [41], [42], [43], [44], [45], [46], [47], [48], [49], [50], [51], [52], [53], [54], [55], [56], [57], [58], [59], [60], [61] are discussed in this article) have examined the potential to replace fossil fuel energysources with renewable energy. Since wind and solar power dominate the expandable potentials of renewable energy [3], a primary focus for studies with high shares of renewables is the need to balance the variability of these energy sources in time and space against the demand for energy services.
The studies that examine scenarios with very high shares of renewable energy have attracted a critical response from some quarters, particularly given that high targets for renewable energy are now part of government policy in many countries [62], [63]. Critics have challenged studies for purportedly not taking sufficient account of: the variability of wind and solar [64], [65], the scaleability of some storage technologies [66], all aspects of system costs [64], [65], resource constraints [67], [68], social acceptance constraints [68], energy consumption beyond the electricity sector [68], limits to the rate of change of the energy intensity of the economy [68] and limits on capacity deployment rates [69], [68]. Many of these criticisms have been rebutted either directly [70], [71], [72] or are addressed elsewhere in the literature, as we shall see in the following sections.
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In this response article we argue that the authors' chosen feasibility criteria may in some cases be important, but that they are all easily addressed both at a technical level and economically at low cost. We therefore conclude that their feasibility criteria are not useful and do not affect the conclusions of the reviewed studies. Furthermore, we introduce additional, more relevant feasibility criteria, which renewable energy scenarios fulfil, but according to which nuclear power, which the authors have evaluated positively elsewhere [74], [75], [76], fails to demonstrate adequate feasibility.
2. Feasibility versus viability
Early in their methods section, the authors define feasibility to mean that something is technically possible in the world of physics 'with current or near-current technology'. They distinguish feasibility from socio-economic viability, which they define to mean whether it is possible within environmental and social constraints and at a reasonable cost. While there is no widely-accepted definition of feasibility [77], other studies typically include economic feasibility in their definition [78], [79], [80], [81], [82], while others also consider social and political constraints [83], [68]. For the purposes of this response article, we will keep to the authors' definitions of feasibility and viability.
One reason that few studies focus on such a narrow technical definition of feasibility is that, as we will show in the sections below, there are solutions using today's technology for all the feasibility issues raised by the authors. The more interesting question, which is where most studies rightly focus, is how to reach a high share of renewables in the most cost-effective manner, while respecting environmental, social and political constraints. In other words, viability is where the real debate should take place. For this reason, in this paper we will assess both the feasibility and the viability of renewables-based energy systems.
Furthermore, despite their declared focus on feasibility, the authors frequently mistake viability for feasibility. Examples related to their feasibility criteria are examined in more detail below, but even in the discussion of specific model results there is confusion. The authors frequently quote from cost-optimisation studies that 'require' certain investments. For example they state that [84] 'required 100 GWe of nuclear generation and 461 GWe of gas' and [85] 'require long-distance interconnector capacities that are 5.7 times larger than current capacities'. Optimisation models find the most cost-effective (i.e. viable) solutions within technical constraints (i.e. the feasible space). An optimisation result is not necessarily the only feasible one; there may be many other solutions that simply cost more. More analysis is needed to find out whether an investment decision is 'required' for feasibility or simply the most cost-effective solution of many. For example, the 100 GWe of nuclear in [84] is fixed even before the optimisation, based on existing nuclear facilities, and is therefore not the result of a feasibility study. However, the authors do acknowledge that their transmission feasibility criteria 'could arguably be regarded as more a matter of viability than feasibility'.
Finally, when assessing economic viability, it is important to keep a sense of perspective on costs. If Europe is taken as an example, Europe pays around 300–400 billion € for its electricity annually.1 EU GDP in 2016 was 14.8 trillion € [86]. Expected electricity network expansion costs in Europe of 80 billion € until 2030 [89] may sound high, but once these costs are annualised (e.g. to 8 billion €/a), it amounts to only 2% of total spending on electricity, or 0.003 €/kWh.
3. Feasibility criteria
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We observe that the authors' choice of criteria, the weighting given to them and some of the scoring against the criteria are somewhat arbitrary. As argued below, there are other criteria that the authors did not use in their rating that have a stronger impact on feasibility (such as resource constraints and technological maturity); based on the literature review below, the authors' criteria would receive a much lower weighting than these other, more important criteria; and the scoring of some of the criteria, particularly for primary energy, transmission and ancillary services, seems coarse and subjective. Regarding the scoring, for demand projections the studies are compared with a spectrum from the mainstream literature, but no uncertainty bound is given, just a binary score; for transmission there is no nuance between studies that use blanket costs for transmission, or only consider cross-border capacity, or distribution as well as transmission networks; and no weighting is given to the importance of the different ancillary services.
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3.1. Their feasibility criterion 1: Demand projections
The authors criticise some of the studies for not using plausible projections for future electricity and total energy demand. In particular, they claim that reducing global primary energy consumption demand is not consistent with projected population growth and development goals in countries where energy demand is currently low.
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However, the authors chose to focus on primary energy, for which the situation is more complicated, and it is certainly plausible to decouple primary energy consumption growth from meeting the planet's energy needs. Many countries have already decoupled primary energy supply from economic growth; Denmark has 30 years of proven history in reducing the energy intensity of its economy [92].
There are at least three points here: i) primary energy consumption automatically goes down when switching from fossil fuels to wind, solar and hydroelectricity, because they have no conversion losses according to the usual definition of primary energy; ii) living standards can be maintained while increasing energy efficiency; iii) renewables-based systems avoid the significant energy usage of mining, transporting and refining fossil fuels and uranium.
Fig. 1 illustrates how primary energy consumption can decrease by switching to renewable energy sources, with no change in the energy services (blue) delivered. Using the 'physical energy accounting method' used by the IEA, OECD, Eurostat and others, or the 'direct equivalent method' used by the IPCC, the primary energy consumption of fossil fuel power plants corresponds to the heating value, while for wind, solar and hydro the electricity output is counted. This automatically leads to a reduction in the primary energy consumption of the electricity sector when switching to wind, solar and hydro, because they have no conversion losses (by this definition).
Fig. 1. Primary energy consumption (grey and green) versus useful energy services (blue) in today's versus tomorrow's energy system.
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If statistics from the European Union in 2015 [101] are taken as an example, taking the steps outlined in Fig. 1 would reduce total primary energy consumption by 49%2without any change in the delivered energy services. (Final energy consumption would also drop by 33%.) A reduction of total primary energy of 49% would allow a near doubling of energy service provision before primary energy consumption started to increase. This is even before efficiency measures and the consumption from fuel processing are taken into account.
The primary energy accounting of different energy sources presented in this example is already enough to explain the discrepancies between the scenarios plotted in Fig. 1 of [73], where the median of non-NGO global primary energy consumption increases by around 50% between 2015 and 2050, while the NGOs Greenpeace and WWF see light reductions.
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The authors chose to concentrate on primary energy consumption, but for renewables, as argued above, it can be a misleading metric (see also the discussion in [96]). The definitions of both primary and final energy are suited for a world based on fossil fuels. What really matters is meeting people's energy needs (the blue boxes in Fig. 1) while also reducing greenhouse gas emissions.
Next we address energy efficiency that goes beyond just switching fuel source. There is plenty of scope to maintain living standards while reducing energy consumption: improved building insulation and design to reduce heating and cooling demand, more efficient electronic devices, efficient processes in industry, better urban designto lower transport demand, more public transport and reductions in the highest-emission behaviour. These efficiency measures are feasible, but it is not clear that they will all be socio-economically viable.
One final, critical point: even if future demand is higher than expected, this does not mean that 100% renewable scenarios are infeasible. As discussed in Section 3.6, the global potential for renewable generation is several factors higher than any demand forecasts. There is plenty of room for error if forecasts prove to underestimate demand growth: an investigation into the United States Energy Information Administration's Annual Outlook [106] showed systematic underestimation of total energy demand by an average of 2% per year after controlling for other sources of projection errors; over 35 years this would lead to an underestimate of around factor 2 (assuming other sources of growth are not excessive); reasonable global potentials for renewable energy could generate on average around 620 TW [3], which is a factor 30 higher than business-as-usual forecasts for average global end-use energy demand of 21 TW in 2050 [36].
3.2. Their feasibility criterion 2a: Simulation time resolution
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It is of course important that models have enough time resolution to capture variations in energy demand (e.g. lower electricity consumption at 3 a.m. than at 3 p.m.) and variations in wind and solar generation, so that balancing needs, networks and other flexibility options can be dimensioned correctly. However, the time resolution depends on the area under consideration, since short-term weather fluctuations are not correlated over large distances and therefore balance out. This criterion should rather read 'the time resolution should be appropriate to the size of the area being studied, the weather conditions found there and the research question'. Models for whole countries typically use hourly simulations, and we will argue that this is sufficient for long-term energy system planning.
After all, why do the authors stop at 5 min intervals? For a single wind turbine, a gust of wind could change the feed-in within seconds (the inertia of the rotor stops faster changes). Similarly, a cloud could cover a small solar panel in under a second. Individuals can change their electricity consumption at the flick of a switch.
The reason modelling in this temporal detail is not needed is the statistical smoothing when aggregating over a large area containing many generators and consumers. Many of the studies are looking at the national or sub-national level. By modelling hourly, the majority of the variation of the demand and variable renewables like wind and solar over these areas is captured; if there is enough flexibility to deal with the largest hourly variations, there is enough to deal with any intra-hour imbalance. Fig. 2 shows correlations in variations (i.e. the differences between consecutive production values) in wind generation at different time and spatial scales.3 Changes within 5 min are uncorrelated above 25 km and therefore smooth out in the aggregation. Further analysis of sub-hourly wind variations over large areas can be found in [108], [109].
Fig. 2. Correlation of variations in wind for different time scales in Germany.
For solar photovoltaics (PV) the picture is similar at shorter time scales: changes at the 5-min level due to cloud movements are not correlated over large areas. However, at 30 min to 1 h there are correlated changes due to the position of the sun in the sky or the passage of large-scale weather fronts. The decrease of PV output in the evening can be captured at one-hour resolution and there are plenty of feasible technologies available for matching that ramping profile: flexible open-cycle gas turbines can ramp up within 5–10 min, hydroelectric plants can ramp within minutes or less, while battery storage and demand management can act within milliseconds. For ramping down, solar and wind units can curtail their output within seconds.
The engineering literature on sub-hourly modelling confirms these considerations. Several studies consider the island of Ireland, which is particularly challenging since it is an isolated synchronous area, is only 275 km wide and has a high penetration of wind. One power system study for Ireland with high share of wind power [112] varied temporal resolution between 60 min and 5 min intervals, and found that the 5 min simulation results gave system costs just 1% higher than hourly simulation results; however, unit commitment constraints and higher ramping and cycling rates could be problematic for older thermal units (but not for the modern, flexible equipment outlined above). Similarly, [113], [114] see not feasibility problems at sub-hourly time resolutions, but a higher value for flexible generation and storage, which can act to avoid cycling stress on older thermal plants. In [115] the difference between hourly and 15-min simulations in small district heating networks with high levels of wind power penetration was considered and it was found that 'the differences in power generation are small' and 'there is [no] need for higher resolution modelling'.
To summarise, since at large spatial scales the variations in aggregated load, wind and solar time series are statistically smoothed out, none of the large-scale model results change significantly when going from hourly resolution down to 5-min simulations. Hourly modelling will capture the biggest variations and is therefore adequate to dimension flexibility requirements. (Reserve power and the behaviour of the system in the seconds after faults are discussed separately in Section 3.5.) Sub-hourly modelling may be necessary for smaller areas with older, inflexible thermal power plants, but since flexible peaking plant and storage are economically favoured in highly renewable systems, sub-hourly modelling is less important in the long-term.
Simulations with intervals longer than one hour should be treated carefully, depending on the research question [116].
3.3. Their feasibility criterion 2b: Extreme climatic events
The authors reserve a point for studies that include rare climatic events, such as long periods of low sun and wind, or years when drought impacts the production of hydroelectricity.
Periods of low sun and wind in the winter longer than a few days can be met, where available, by hydroelectricity, dispatchable biomass, demand response, imports, medium-term storage, synthetic gas from power-to-gas facilities (the feasibility of each of these is discussed separately below) or, in the worst case, by fossil fuels.
From a feasibility point of view, even in the worst possible case that enough dispatchable capacity were maintained to cover the peak load, this does not invalidate these scenarios. The authors write "ensuring stable supply and reliability against all plausible outcomes…will raise costs and complexity". Yet again, a feasibility criterion has become a viability criterion.
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A recent study of seven different weather years (2006–2012), including extreme weather events, in Europe for a scenario with a 95% CO2 reduction compared to 1990 in electricity, heating and transport [119] came to similar conclusions. The extreme events do not affect all countries simultaneously so, for example, Germany can cover extreme events by importing power from other countries. If for political reasons each country is required to cover its peak load on a national basis, the extra costs for capacity are at most 3% of the total system costs.
For systems that rely on hydroelectricity, the authors are right to point out that studies should be careful to include drier years in their simulations. Beyond the examples they cite, Brazil's hydroelectric production has been restricted over the last couple of years due to drought, and there are periodic drier years in Ethiopia, Kenya and Scandinavia, where in the latter inflow can drop to 30% below the average [108].
However, in most countries, the scenarios rely on wind and solar energy, and here the dispatchable power capacity of the hydro is arguably just as important in balancing wind and solar as the total yearly energy contribution, particularly if pumping can be used to stock up the hydro reservoirs in times of wind and solar abundance [7], [54].
Note that nuclear also suffers from planned and unplanned outages, which are exacerbated during droughts and heatwaves, when the water supplies for river-cooled plants are either absent or too warm to provide sufficient cooling [120]. This problem is likely to intensify given rising demand for water resources and climate change [120].
3.4. Their feasibility criterion 3: Transmission and distribution grids
The authors criticise many of the studies for not providing simulations of the transmission (i.e. high voltage long-distance grid) and distribution (i.e. lower voltage distribution from transmission substations to consumers) grids. Again, this is important, but not as important as the authors assume. Feasibility is not the issue (there are no technical restrictions on expanding the grid), but there are socio-economic considerations. Many studies that do not model the grid, do include blanket costs for grid expansion (e.g. from surveys such as [121], [122], [123]).
On a cost basis, the grid is not decisive either: additional grid costs tend to be a small fraction of total electricity system costs (examples to follow, but typically around 10–15% of total system costs in Europe [124], [125], [126], [127], [21], [42], [123]), and optimal grid layouts tend to follow the cheapest generation, so ignoring the grid is a reasonable first order approximation. Where it can be a problem is if public acceptance problems prevent the expansion of overhead transmission lines, in which case the power lines have to be put underground (typically 3–8 times more expensive than overhead lines) or electricity has to be generated more locally (which can drive up costs and may require more storage to balance renewables). Public acceptance problems affect cost, i.e. economic viability, not feasibility.
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A study by Imperial College, NERA and DNV GL for the European electricity system to 2030 [124] examined the consequences for both the transmission and distribution grid of renewable energy penetration up to 68% (in their Scenario 1). For total annual system costs of 232 billion €/a in their Scenario 1, 4 billion €/a is assigned to the costs of additional transmission grid investments and 18 billion €/a to the distribution grid. If there is a greater reliance on decentralised generation (Scenario 1(a)-DG), additional distribution grid costs could rise to 24 billion €/a.
This shows a typical rule of thumb: additional grid costs are around 10–15% of total system costs. But this case considered only 68% renewables.
The distribution grid study of 100% renewables in the German federal state of Rhineland-Palatinate (RLP) [125] also clearly demonstrates that the costs of generation dwarf the grid costs. Additional grid investments vary between 10% and 15% of the total costs of new generation, depending on how smart the system is. Again, distribution upgrade costs dominate transmission costs.
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The authors quote studies that look at optimal cross-border transmission capacity in Europe at very high shares of renewables, which show an expansion of 4–6 times today's capacities [85], [129]. It is worth pointing out that these studies look at the international interconnectors, not the full transmission grid, which includes the transmission lines within each country. The interconnectors are historically weak compared to national grids4 and restricted by poor market design and operation [130]; if a similar methodology to [85], [129] is applied to a more detailed grid model with nodal pricing, the expansion is only between 25% and 50% more than today's capacity [42]. Furthermore, cost-optimal does not necessarily mean socially viable; there are solutions with lower grid expansion and hence higher public acceptance, but higher storage costs to balance renewables locally [42].
3.5. Their feasibility criterion 4: Ancillary services
Finally, we come to ancillary services. Ancillary services are additional services that network operators need to stabilise and secure the electricity system. They are mostly provided by conventional dispatchable generators today. Ancillary services include reserve power for balancing supply and demand in the short term, rotating inertia to stabilise the frequency in the very short term, synchronising torque to keep all generators rotating at the same frequency, voltage support through reactive power provision, short circuit current to trip protection devices during a fault, and the ability to restart the system in the event of a total system blackout (known as 'black-starting'). The authors raise concerns that many studies do not consider the provision of these ancillary services, particularly for voltage and frequency control. Again, these concerns are overblown: ancillary services are important, but they can be provided with established technologies (including wind and solar plants), and the cost to provide them is second order compared to the costs of energy generation.
We consider fault current, voltage support and inertia first. These services are mostly provided today by synchronous generators, whereas most new wind, solar PV and storage units are coupled to the grid with inverters, which have no inherent inertia and low fault current, but can control voltage with both active and reactive power.
From a feasibility point of view, synchronous compensators could be placed throughout the network and the problem is solved, although this is not as cost effective as other solutions. Synchronous compensators (SC), also called synchronous condensers, are essentially synchronous generators without a prime mover to provide active power. This means they can provide all the ancillary services of conventional generators except those requiring active power, i.e. they can provide fault current, inertia and voltage support just like a synchronous generator. Active power is then provided by renewable generators and storage devices.
In fact, existing generators can be retrofitted to be SC, as happened to the nuclear power plant in Biblis, Germany [131], or to switch between generation mode and SC mode; extra mass can be added with a clutch if more inertia is needed (SC have an inertia time constant of 1–2 s [132], [133], compared to typical conventional generators with around 6 s). SC are a tried-and-tested technology and have been installed recently in Germany [134], Denmark, Norway, Brazil, New Zealand and California [135]. They are also used in Tasmania [136], where 'Hydro Tasmania, TasNetworks and AEMO have implemented many successful initiatives that help to manage and maintain the security of a power system that has a high penetration of asynchronous energy sources…Some solutions implemented in Tasmania have been relatively low cost and without the need for significant capital investment' [136]. In Denmark, newly-installed synchronous compensators along with exchange capacity with its neighbours allow the power system to operate without any large central power stations at all [137].
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Next, we consider balancing reserves. Balancing power can be provided by traditional providers, battery systems, fast-acting demand-side-management or by wind and solar generators (upward reserves are provided by variable renewable plants by operating them below their available power, called 'delta' control). There is a wide literature assessing requirements for balancing power with high shares of renewables. In a study for Germany in 2030 with 65 GW PV and 81 GW wind (52% renewable energy share), no need is seen for additional primary reserve, with at most a doubling of the need for other types of reserves [161]. It is a similar story in the 100% renewable scenario for Germany of Kombikraftwerk 2 [162]. (Maintaining reserves in Germany cost 315.9 million € in 2015 [163].) There is no feasibility problem here either.
Another ancillary service the authors mention is black-start capability. This is the ability to restart the electricity system in the case of a total blackout. Most thermal power stations consume electricity when starting up (e.g. powering pumps, fans and other auxiliary equipment), so special provisions are needed when black-starting the system, by making sure there are generators which can start without an electricity supply. Typically system operators use hydroelectric plants (which can generate as soon as the sluice gate is opened), diesel generators or battery systems, which can then start a gas turbine, which can then start other power plants (for example). Maintaining conventional capacity for black-start is inexpensive compared to system costs, as shown in Section 3.3; in a study for Germany in 2030 [161] with 52% renewables, no additional measures for black-starting were deemed necessary, contrary to the interpretation in [73]; finally, decentralised renewable generators and storage could also participate in black-starting the system in future [162]. The use of battery storage systems to black-start gas turbines has recently been demonstrated in Germany [164] and in a commercial project in California [165].
Nuclear, on the other hand, is a problem for black-starting, since most designs need a power source at all times, regardless of blackout conditions, to circulate coolant in the reactor and prevent meltdown conditions. This will only exacerbate the need for backup generation in a total blackout. Nuclear is sometimes not used to provide primary reserves either, particularly in older designs, because fast changes in output present operational and safety concerns.
3.6. Our feasibility criterion 5: Fuel source that lasts more than a few decades
Here we suggest a feasibility criterion not included on the authors' list: The technology should have a fuel source that can both supply all the world's energy needs (not just electricity, but also transport, heating and industrial demand) and also last more than a couple of decades.
Traditional nuclear plants that use thermal-neutron fission of uranium do not satisfy this feasibility criterion. In 2015 there were 7.6 million tonnes of identified uranium resources commercially recoverable at less than 260 US$/kgU [166].5 From one tonne of natural uranium, a light-water reactor can generate around 40 GWh of electricity.
In 2015, world electricity consumption was around 24,000 TWh/a [168]. Assuming no rise in electricity demand and ignoring non-electric energy consumption such as transport and heating, uranium resources of 7.6 million tonnes will last 13 years. Reprocessing, at higher cost, might extend this by a few more years. Including non-electric energy consumption would more than halve this time.
For renewables, exploitable energy potentials exceed yearly energy demand by several orders of magnitude [169] and, by definition, are not depleted over time. Even taking account of limitations of geography and material resources, the potentials for the expansion of wind, solar and storage exceed demand projections by several factors [3].
As for 'following all paths' and pursuing a mix of renewables and nuclear, they do not mix well: because of their high capital costs, nuclear power plants are most economically viable when operated at full power the whole time, whereas the variability of renewables requires a flexible balancing power fleet [170]. Network expansion can help the penetration of both renewables and inflexible plant [171], but this would create further pressure for grid expansion, which is already pushing against social limits in some regions.
This feasibility criterion is not met by standard nuclear reactors, but could be met in theory by breeder reactors and fusion power. This brings us to our next feasibility criterion.
3.7. Our feasibility criterion 6: Should not rely on unproven technologies
Here is another feasibility criterion that is not included on the authors' list: Scenarios should not rely on unproven technologies. We are not suggesting that we should discontinue research into new technologies, rather that when planning for the future, we should be cautious and assume that not every new technology will reach technical and commercial maturity.
The technologies required for renewable scenarios are not just tried-and-tested, but also proven at a large scale. Wind, solar, hydro and biomass all have capacity in the hundreds of GWs worldwide [63]. The necessary expansion of the grid and ancillary services can deploy existing technology (see 3.4 Their feasibility criterion 3: Transmission and distribution grids, 3.5 Their feasibility criterion 4: Ancillary services). Heat pumps are used widely [172]. Battery storage, contrary to the authors' paper, is a proven technology already implemented in billions of devices worldwide (including a utility-scale 100 MW plant in South Australia [173] and 700 MW of utility-scale batteries in the United States at the end of 2017 [174]). Compressed air energy storage, thermal storage, gas storage, hydrogen electrolysis, methanation and fuel cells are all decades-old technologies that are well understood. (See Section 4.1for more on the feasibility of storage technologies.)
On the nuclear side, for the coming decades when uranium for thermal-neutron reactors would run out, we have breeder reactors, which can breed more fissile material from natural uranium or thorium, or fusion power.
Breeder reactors are technically immature (with a technology readiness levelbetween 3 and 5 depending on the design [175]), more costly than light-water reactors, unreliable, potentially unsafe and they pose serious proliferation risks [176]. Most fast-neutron breeder reactors rely on sodium as a coolant, and since sodium burns in air and water, it makes refueling and repair difficult. This has led to serious accidents in fast breeder reactors, such as the major sodium fire at the Monju plant in 1995. Some experts consider fast breeders to have already failed as a technology option [176], [177]. The burden of proof is on the nuclear industry to demonstrate that breeder reactors are a safe and commercially competitive technology.
Fusion power is even further from demonstrating technical feasibility. No fusion plant exists today that can generate more energy than it requires to initiate and sustain fusion. Containment materials that can withstand the neutronbombardment without generating long-lived nuclear waste are still under development. Even advocates of fusion do not expect the first commercial plant to go online before 2050 [178]. Even if it proves to be feasible and cost-effective (which is not clear at this point), ramping up to a high worldwide penetration will take decades more. That is too late to tackle global warming [179].
4. Other issues
In this section we address other issues raised by the authors of [73] during their discussion of their feasibility criteria.
4.1. Feasibility of storage technologies
The authors write "widespread storage of energy using a range of technologies (most of which - beyond pumped hydro - are unproven at large scales, either technologically and/or economically)".
Regarding battery storage, it is clear that there is the potential to exploit established lithium ion technology at scale and at low cost [180], [181], [182]. The technology is already widely established in electronic devices and increasingly in battery electric vehicles, which will in future provide a regular and cheap source of second-life stationary batteries. A utility-scale 100 MW plant was installed in the South Australian grid in 2017 [173] and there was already 700 MW of utility-scale batteries in the United States at the end of 2017 [174]. Further assessments of the potential for lithium ion batteries can be found in [3]. Costs are falling so fast that hybrid PV-battery systems are already or soon will be competitive with conventional systems in areas with good solar resources [183], [184].
Many other electricity storage devices have been not just demonstrated but already commercialised [185], including large-scale compressed air energy storage. Technologies that convert electricity to gas, by electrolysing hydrogen with the possibility of later methanation, are already being demonstrated at megawatt scale [186], [187]. Hydrogen could either be fed into the gas network to a certain fraction, used in fuel cell vehicles, converted to other synthetic fuels, or converted back into electricity for the grid. Fuel cells are already manufactured at gigawatt scale, with 480 MW installed in 2016 [188]. By using the process heat from methanation to cover the heat consumption of electrolysis, total efficiency for power-to-methane of 76% has recently been demonstrated in a freight-container-sized pilot project, with 80% efficiency in sight [189].
Moreover, in a holistic, cross-sectoral energy systems approach that goes beyond electricity to integrate all thermal, transport and industrial demand, it is possible to identify renewable energy systems in which all storage is based on low-cost well-proven technologies, such as thermal, gas and liquid storage, all of which are cheaper than electricity storage [190]. These sectors also provide significant deferrable demand, which further helps to integrate variable renewable energy [191], [29], [46]. Storage capacity for natural gas in the European Union is 1075 TWh as of mid 2017 [192].
4.2. Feasibility of biomass
The authors criticise a few studies for their over-reliance on biomass, such as one for Denmark [10] and one for Ireland [11]. There are legitimate concerns about the availability of fuel crops, environmental damage, biodiversity loss and competition with food crops [193]. More recent studies, including some by the same researchers, conduct detailed potential assessments for biomass and/or restrict biomass usage to agricultural residues and waste [194], [98], [195], [22]. Other studies are even more conservative (or concerned about air pollution from combustion products [87]) and exclude biomass altogether [41], [3], [7], [36], [46], while still reaching feasible and cost-effective energy systems.
4.3. Feasibility of carbon capture
Capturing carbon dioxide from industrial processes, power plants or directly from the air could also contribute to mitigating net greenhouse gas emissions. The captured carbon dioxide can then be used in industry (e.g. in greenhouses or in the production of synthetic fuels) or sequestered (e.g. underground). While some of the individual components have been demonstrated at commercial scale, hurdles [196], [197], [198] include cost, technical feasibility of long-term sequestration without leakage, viability for some concepts (such as direct air capture (DAC), the lowest cost version of which is rated at Technology Readiness Level (TRL) 3–5 [199]), other air pollutants from combustion and imperfect capture when capturing from power plants, lower energy efficiency, regulatory issues, public acceptance of sequestration facilities [200] and systems integration.
Studies at high time resolution that have combined renewables and power plants with carbon capture and sequestration (CCS) suggest that CCS is not cost effective because of high capital costs and low utilisation [201]. However, DAC may be promising for the production of synthetic fuels [29], [202], [203] and is attractive because of its locational flexibility and minimal water consumption [204], [205]. Negative emissions technologies (NET), which include DAC, bioenergy with CCS, enhanced weathering, ocean fertilisation, afforestation and reforestation, may also be necessary to meet the goals of the Paris climate accord [206], [207], [208], [209]. Relying on NET presents risks given their technical immaturity, so further research and development of these technologies is required [206], [210], [211], [212].
4.4. Viability of renewable energy systems
With regard to social viability, there are high levels of public support for renewable energy. In a survey of European Union citizens for the European Commission in 2017, 89% thought it was important for their national government to set targets to increase renewable energy use by 2030 [213]. A 2017 survey of the citizens of 13 countries from across the globe found that 82% believe it is important to create a world fully powered by renewable energy [214]. A 2016 compilation of surveys from leading industrialised countries showed support for renewables in most cases to be well over 80% [215]. Concerns have been raised primarily regarding the public acceptance of onshore wind turbines and overhead transmission lines. Repeated studies have shown that public acceptance of onshore wind can be increased if local communities are engaged early in the planning process, if their concerns are addressed and if they are given a stake in the project outcome [216], [217], [218]. Where onshore wind is not socially viable, there are system solutions with higher shares of offshore wind and solar energy, but they may cost fractionally more [219]. The picture is similar with overhead transmission lines: more participatory governance early in the planning stages and local involvement if the project is built can increase public acceptance [220], [221]. Again, if overhead transmission is not viable, there are system solutions with more storage and underground cables, but they are more expensive [42]. The use of open data and open model software can help to improve transparency [222], [223], [224].
Next we turn to the economic viability of bulk energy generation from renewable sources. On the basis of levelised cost, onshore wind, offshore wind, solar PV, hydroelectricity and biomass are already either in the range of current fossil fuelgeneration or lower cost [225]. Levelised cost is only a coarse measure [226], since it does not take account of variability, which is why integration studies typically consider total system costs in models with high spatial and temporal resolution. Despite often using conservative cost assumptions, integration studies repeatedly show that renewables-based systems are possible with costs that are comparable or lower than conventional fossil-fuel-based systems [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35], [36], [37], [38], [39], [40], [41], [42], [43], [44], [45], [46], [47], [48], [49], [50], [51], [52], [53], [54], [55], [56], [57], [58], [59], [60], [61], even before aspects such as climate impact and health outcomes are considered.
For example, focusing on results of our own research, a global switch to 100% renewable electricity by 2050 would see a drop in average system cost from 70 €/MWh in 2015 to 52 €/MWh in 2050 [35]. This study modelled the electricity system at hourly resolution for an entire year for 145 regions of the world. Considering all energy sectors in Europe, costs in a 100% renewable energy scenariowould be only 10% higher than a business-as-usual scenario for 2050 [22].
4.5. Viability of nuclear power
Following the authors, we have focused above on the technical feasibility of nuclear. For discussions of the socio-economic viability of nuclear power, i.e. the cost, safety, decomissioning, waste disposal, public acceptance, terrorism and nuclear-weapons-proliferation issues resulting from current designs, see for example [227], [3], [167], [228].
4.6. Other studies of 100% renewable systems
At the time the authors submitted their article there were many other studies of 100% or near-100% renewable systems that the authors did not review. Most studies were simulated with an hourly resolution and many modelled the transmission grid, with examples covering the globe [14], [15], North-East Asia [16], the Association of South-East Asian Nations (ASEAN) [17], Europe and its neighbours [18], Europe [19], [20], [21], [22], [23], South-East Europe [24], the Americas [25], China [26], the United States [27], Finland [28], Denmark [29], Germany [30], Ireland [31], Portugal [32] and Berlin-Brandenburg in Germany [33].
Since then other 100% studies have considered the globe [34], [35], [36], [37], Asia [38], Southeast Asia and the Pacific Rim [39], Europe [40], [41], [42], [43], [44], [45], [46], South-East Europe [47], South and Central America [48], North America [49], India and its neighbours [50], [51], Australia [52], [53], Brazil [54], Iran [55], Pakistan [56], Saudi Arabia [57], Turkey [58], Ukraine [59] the Canary Islands [60] and the Åland Islands [61].
4.7. Places already at or close to 100% renewables
The authors state that the only developed nation with 100% renewable electricity is Iceland. This statement ignores countries which come close to 100% and smaller island systems which are already at 100% (on islands the integration of renewables is harder, because they cannot rely on their neighbours for energy trading or frequency stability), which the authors of [73] chose to exclude from their study.
Countries which are close to 100% renewable electricity include Paraguay (99%), Norway (97%), Uruguay (95%), Costa Rica (93%), Brazil (76%) and Canada (62%) [146]. Regions within countries which are at or above 100% include Mecklenburg-Vorpommern in Germany, Schleswig-Hostein in Germany, South Island in New Zealand, Orkney in Scotland and Samsø along with many other parts of Denmark.
This list mostly contains examples where there is sufficient synchronous generation to stabilise the grid, either from hydroelectricity, geothermal or biomass, or an alternating current connection to a neighbour. There are also purely inverter-based systems on islands in the South Pacific (Tokelau [229] and an island in American Samoa) which have solar plus battery systems. We could also include here any residential solar plus battery off-grid systems.
Another relevant example is the German offshore collector grids in the North Sea, which only have inverter-based generators and consumption. Inverter-interfaced wind turbines are connected with an alternating current grid to an AC-DC converter station, which feeds the power onto land through a High Voltage Direct Currentcable. There is no synchronous machine in the offshore grid to stabilise it, but they work just fine (after teething problems with unwanted harmonics between the inverters).
Off-planet, there is also the International Space Station and other space probes which rely on solar energy.
4.8. South Australian blackout in September 2016
The authors implicitly blame wind generation for the South Australian blackout in September 2016, where some wind turbines disconnected after multiple faults when tornadoes simultaneously damaged two transmission lines (an extreme event). According to the final report by the Australian Energy Market Operator (AEMO) on the incident [230] "Wind turbines successfully rode through grid disturbances. It was the action of a control setting responding to multiple disturbances that led to the Black System. Changes made to turbine control settings shortly after the event [have] removed the risk of recurrence given the same number of disturbances." AEMO still highlights the need for additional frequency control services, which can be provided at low cost, as outlined in Section 3.5.
5. Conclusions
In 'Burden of proof: A comprehensive review of the feasibility of 100% renewable-electricity systems' [73] the authors called into question the feasibility of highly renewable scenarios. To assess a selection of relevant studies, they chose feasibility criteria that are important, but not critical for either the feasibility or viability of the studies. We have shown here that all the issues can be addressed at low economic cost. Worst-case, conservative technology choices (such as dispatchable capacity for the peak load, grid expansion and synchronous compensators for ancillary services) are not only technically feasible, but also have costs which are a magnitude smaller than the total system costs. More cost-effective solutions that use variable renewable generators intelligently are also available. The viability of these solutions justifies the focus of many studies on reducing the main costs of bulk energy generation.
As a result, we conclude that the 100% renewable energy scenarios proposed in the literature are not just feasible, but also viable. As we demonstrated in Section 4.4, 100% renewable systems that meet the energy needs of all citizens at all times are cost-competitive with fossil-fuel-based systems, even before externalities such as global warming, water usage and environmental pollution are taken into account.
The authors claim that a 100% renewable world will require a 're-invention' of the power system; we have shown here that this claim is exaggerated: only a directed evolution of the current system is required to guarantee affordability, reliability and sustainability.
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This article alone makes a very strong case for the feasibility and viability of 100% renewable systems, but the numerous sources and references that support the article's conclusions are what really makes the argument for 100% renewable systems extremely compelling, and worth considering.
At this point, it would appear that the biggest barrier to transitioning to 100% renewable energy is a political one, not a technical one, and to that end, we need to do everything in our power to make sure to tear that barrier down, or we really are well and truly fucked.
Hmm... Which country to invade to mitigate climate change?
Oh noooooo! Who could have guessed that America would be on the list!
Also..what the fuck is up australia??
Is this some attempt at a gotcha? lol Of course the US is on a list like that.
Why did you literally copy and paste an entire response to a study into this thread? Not to mention you're leaning on number of papers cited when the paper its responding to has more citations.
But let me just respond to this, at least:
The point being made here is that nuclear adjustment is highly inefficient (it is) and as such can't fulfill the variable load part of wind/solar so you can't have a grid with wind/solar/nuclear without storage.... Which is true. Adding wind/solar to a nuclear system makes you require more storage/variable output than a solely nuclear system, but it's not true the other way around. See, nuclear power is a constant output, unlike wind/solar, so it requires less overproduction than wind/solar to make up for variability and it requires less energy storage to make up a full grid. So, every percentage of nuclear requires solar/wind to have less storage than it would otherwise. On the other hand every percentage of solar/wind requires more of an energy storage infrastructure than it would otherwise. So, yes, they do conflict, but in the sense that solar/wind make nuclear less efficient, not otherwise.
Here is the paper that's citation 170:
The paper in question (only the abstract is available and it's a one author 2008 study) throws out nuclear because it's politically unpopular and "riskier" than solar (funny how a proposal being politically unpopular is only a consideration for nuclear when wind turbine installation in Germany has literally stopped because of nimbyism). It's honestly written like a commercial, but putting that aside, the paper itself doesn't state that nuclear makes wind/solar less efficient, it just states that nuclear is too dangerous, also requires variable load so it doesn't SOLVE the issue of solar/wind (it does lessen the problem, however).
Either way, for context, here is the paper its responding to which casts doubt on the feasibility of 100% renewables:
I did not. I read every damn word of that response (and checked every single reference), parsed through the most relevant bits, and copy/pasted what I thought the thread would find interesting based on my understanding of what was rebutted/refuted, and formatted the text for accessibility. For the full response, you're welcome to actually read it at the link I provided.
I will not be responding to anyone else about this if they have not done their due diligence in actually reading it; it would be a waste of my time.
EDIT:
Also, there are plenty of other sources that corroborate their claims, but I will post about them independently because it's simply too much information for one post, and I don't have time to format them all right now.
I'm unconvinced liberals will be able to save us. You guys prove yourselves incapable time and time again, but you jealously hold onto your power and admonish those who are actually trying to make a difference.
David Attenborough voice
Here is the quintessential liberal in his natural element. As you can see, this liberal has eyes on its terrible prey, climate change. It wants to give chase, but it must first formulate a plan on how to catch it. What happens next is truly remarkable. The liberal handicaps itself by breaking one of its appendages, a most unusual strategy. It is already limping from an old break when it tried to get healthcare under control and most recently it gave aid to a monstrous beast that is still feeding on the liberal's children with the excuse "we just want to make conditions better for the children." Meanwhile, other animals nearby are also attempting to stop climate change with more effective methods, but the liberal shouts at them and says, "you absolute idiot, people are dying right now! Don't waste this time looking for a gift from the gods! Now come over here and break your leg, it's the only way to stop this beast!"
This is what's called a mic drop, I believe.
I especially appreciate 3.6, ie. nuclear fuel being a limited resource that has a production cost. When the issue is climate change, the solution needs to be one that minimizes the impact of conversion. Under a worst case mass nuclear scenario, a lot of plants might face premature closure due to rising fuel costs. That after decades of building them for a significant CO2 emission cost might end up causing a resurgence of the climate crisis.
New fuels are coming in the next decade (carbon neutral). 2030 is around the corner though.
Because they are idiots.
Did you read the original study, though? Which itself is a response to the 24 studies that they considered to actually have done enough due diligence to warrant a full response. Regardless, I did read most of your post. The study makes a lot of the same mistakes that the original study criticizes and falls more into theory crafting ("We could massively decrease wasted heat energy by having communal heating systems! Like that isn't an infrastructure and legislative nightmare that isn't even possible everywhere, like what are you gonna do in florida? Build the vents above ground? Or in an area with less density?). They also say that electrical vehicles will reduce primary energy consumption by 70% when, depending on the energy mix they're used in, electric vehicles have more of a carbon footprint than combustion ones. It goes on, but there are dozens of studies that contradict this response, that are in fact cited in the study that this response is trying to counter.
Regardless, your angle here is to have someone who is not a scientist argue with a scientist point by point to avoid considering that there is quite a large section of the scientific community that disagrees that these studies are actually feasible and go into detail on why. What you've been doing here is basically saying to focus on the dozens studies that say 100% renewable is possible, but ignore the dozens that cast doubt on that (and the dozens that specifically cast doubt on the other studies, the vast majority of which are not made by Trump-paid scientists).
It doesn't address the fact that the materials to make solar/wind are also limited. Solar/wind have to be replaced every 20 years so there is a constant cost in resources that aren't infinite. Plants aren't going to be closing because of the cost of nuclear fuel by any stretch, uranium is stupid cheap per kwh and is the smallest part of the cost of nuclear power by orders of magnitude.
Well, what's the wastage rate on renewables vs nuclear then? You brought up copper before. How much copper do we need to achieve 100% renewable power? And how much of it we can then recycle?
So these are the assumptions:
*Note: Li-S batteries are double the energy density or more of lithium ion.
*Note: this is assuming that efficiency increases without changing over to another material, like proposed copper based solar panels.
Reserve assumptions:
Moving on to findings:
Cobalt:
Exceeding current reserves and resources means that recycling would not be enough.
Which means that the price would skyrocket and production would tank.
Silver is ironically more sustainable here.
Self-comparison to other studies:
*Note, the author in this one is the only one looking at 100% renewable
The study gets into a lot more detail, but EV's, solar panels, etc are all very supply constrained and it's impossible to actually meet 100% renewable without running out of resources even with recycling and we'll be hitting supply constraints in 2023 on a 100% renewable by 2050 deadline, better yet a 2030 one.
So it's batteries. Meaning there needs to be focus on alternative storage methods, not that renewable generators themselves use up those resources. My takeaway from that is that unfortunately it seems personal transportation and intenational shipping will both have to be curtailed, until there's a battery revolution or if fuel cells turn out to be feasible.
Note that in a nuclear future you still need those same batteries for transportation.
Feel like you're being slightly disingenuous here Steel, even though the issue of supply constrained materials is an issue down the road.
Reserves aren't inherently a limiting factor, it's just the economic extraction maximum. The way you're describing reserves makes it read like you're describing total extractable resources.
Note that in a nuclear future, the power load won't be cannibalizing nearly as much of those batteries.
Deep sea mining of cobalt is ridiculously inefficient, recognizing that super-low density reserves may be profitable in the future is also recognizing that production will tank to the point where using it is less than feasible (E.g. we'd be spending stupid amounts of effort to deep sea mine cobalt because there is no other easy choice). At current production levels demand already exceeds supply for these materials without any country going ham on 100% renewable and with only 4% of the grid being solar/wind. Also, note that the study in question assumes that production won't ever see a decrease due to harder to mine sites being used and even still we run into supply problems by 2023.