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Monday, September 5, 2016

David Roberts on the latest NREL 30% wind and solar study

As suggested in my earlier article, consider this article to be a comment under David's article: The Eastern US could get a third of its power from renewables within 10years. Theoretically, which has no comment field.

Because David is a self-labeled climate hawk, I'm going to start by addressing (what should be but isn't) the overarching concern of climate hawks with regard to energy production--carbon emissions. Had the study also replaced all remaining coal with nuclear, which technically, is certainly possible as France proved long ago, there would have been a 30% + 33% (see Figure 2) = 63% reduction in emissions. Even more simply, they could have replaced all coal with nuclear from the start and added no renewable energy for an emissions reduction of 46%. But because this study was done by the National Renewable Energy Lab, that possibility was not considered.

Why did they stop at 30% penetration? Why was no attempt made to show what it would cost to implement? We do know what it has cost Germany to get to this approximate level of renewables, as I have pointed out uncounted times before:

I don’t know any other economy that can bear this burden [$30billion a year]...We have to make sure that we connect the energy switch to economic success, or at least not endanger it. Germany must focus on the cheapest clean-energy sources as well as efficient fossil-fuel-fired plants to stop spiraling power prices.

While renewable aid costs are at the “limit” of what the economy can bear, Germany will keep pushing wind and solar power, the most cost-effective renewable sources, Gabriel said. Biomass energy is too expensive and its cost structure hasn’t improved, he said.

Germany is demonstrating the real world cost of trying to reduce emissions with only renewables; $30 billion a year, according to Germany's economics ministry. $30 billion a year would pay for forty custom built $7.5 billion Generation III AP1000 reactors over ten years ($30B/year x 10years  = $300B, $300B/$7.5B = 40 AP1000 reactors). Add those to existing reactors and they could supply about 97% of Germany's electricity by 2025.

The Eastern US could get a third of its power from renewables within 10 years. Theoretically.

That word David stuck on the end of his title is all important and should be in the preface of any of these studies. But what does theoretically mean? David takes a stab at it below:

Prior to the question of how that might be accomplished socially or politically is the simple question of whether it’s technically possible.

 ... the basic conclusion of the study can be summed up in four words: It can be done.

...anyone who says that the densely populated eastern US can’t do it without threatening service and reliability is, according to the best available research, simply wrong.

He got the social and political part right but technical feasibility ("it can be done") ...not so much. Let me give you an example. 2 + 3 = 5. That's not a theoretical answer. If the value of two or three are assumed rather than being factual, the answer becomes theoretical. The more assumptions in a study, the more theoretical are the answers. This study relies on several hundred assumptions. Both the amount of wind and solar that can technically be integrated as well as the time frame for it have wide error bands. And there is no mention of cost.

  1. Socially
  2. Politically
  3. Technologically
  4. Economically

So, I agree that the study does not solve social or political problems, but it also does not  prove economic viability (may not be the lowest cost solution) and technical viability in this case is largely a matter of money. Germany certainly had similar studies before they launched their energy transition.

And of course, this is just one study. We should never base policy on a single study. Our cars would be powered entirely by food crop-based biofuels (instead of today's mere 10%) if fuel policy were dictated by a single study from the corn growers association. A single study has limited value.

The study is a remarkable technical achievement, marrying enormous datasets with enormous computing power to produce incredibly rich scenarios (one reason it stretches to 220 pages, with six appendices).

Doesn't sound all that impressive considering that a few years ago they produced a four-volume study (where the first volume alone was 280 pages) suggesting that 80% of our grid could be renewable by 2050.

Simulating the behavior of that machine under different resource scenarios involves running millions of equations, for every one of those nodes, at every interval, ranging over gigantic datasets. It wasn’t even possible until recently, which is why analysis has relied so heavily on assumptions and educated guesses.

Which is a big improvement over their four-volume study I mentioned earlier suggesting 80% renewables and maybe that explains why the estimate has dropped to 30%, but still, this study required many assumptions, in large part because the future can't be predicted with certainty.

Interestingly, NREL modeled nuclear plants as entirely inflexible, unable to ramp, though there’s some evidence that’s not true.

Below I show you the graph that David (knowing that nobody follows links) only linked to:

Figure 1: Ontario Nuclear Flexibility

This is how the NREL put it:

This is a conservative assumption, as nuclear plants in several countries and the Pacific Northwest have decades of successful flexible plant operation

By conservative they mean that flexible use of nuclear power would likely have reduced use of natural gas and increased the penetration of wind and solar. My guess is that they don't want to show nuclear power having any benefit.

These kinds of things — the political, social, and institutional changes — are more difficult than the technological challenge. And unfortunately, there is no model, no simulation, and no supercomputer that can show us how to induce today’s socioeconomic institutions and their leaders to behave in a more clueful fashion.

He's right about the political, social, and institutional hurdles. But because David is at heart, not "pro-nuclear," it didn't dawn on him that those hurdles are also standing in the way of using more nuclear in the mix.

It’s probably worth at least mentioning that increasing VG penetration to 30 percent would also reduce greenhouse gas emissions from the EI by 30 percent. That’s a lot.

Although David commends the authors for providing full disclosure, I wish you luck finding the data behind the bar charts provided in the summary. Figure 93 shows a >30% reduction in emissions but appears to contradict what is shown in Figure 2 below, which would suggest something more like a 20% reduction on the "system." I'd love to know why. It's partly because the study states that "approximately" 30% wind and solar was installed (didn't quite make it to 30%) and partly because much of the power replaced was gas, which, assuming that it produces roughly half the emissions of coal, will have less impact on emissions reductions on the system than reducing power from coal. 30% or 19% is better than nothing, but it's also not as good as 30% + 33% = 63%.

Figure 2: Adapted from Figure 43 of the study

I suspect that the study stops at 30% wind and solar because according to another study done by the NREL penetrations much beyond that "could test the economic carrying capacity of the U.S. power grid":

"Still higher levels of variable renewable energy generation [wind and solar above 30%] is technically feasible but could test the economic carrying capacity of the U.S. power grid."

Note that the study uses the acronym VG (variable generation) for wind and solar. Why they didn't simply say "wind and solar" is beyond me.

From the study:

Nuclear units were assumed to operate at their maximum capacity at all times that they were not on a planned or forced outage.

Why did they assume there would be no closure of nuclear like that in California? I think the answer is that replacing nuclear with wind and solar would make their emissions numbers look worse. Assuming a decision was made to let all nuclear close instead of fossil fuels (as Germany did) all of this effort would result in a 3% increase in emissions. Closing half of nuclear would have resulted in only an 8.8% reduction and so it goes. Moral of the story? Don't close nuclear power stations.

David continues:

NREL did not model a substantial role for emerging technologies and practices like grid-connected battery storage and demand response. If thost techs flourish — and signs are good —it's likely the grid could accommodate much more than 30 percent in 10 years.

Never mind that the study didn't make it all the way to 30%, they didn't model a substantial role for storage and demand response specifically because the signs are not good for them making significant headway in that timeframe.

Let’s pause a moment and give thanks for America’s extraordinary national laboratories, which continue pumping out high-quality research at a pace I can barely keep up with. (Special shout out to Aaron Bloom, NREL’s project leader on this study.)

Let's pause a moment and give thanks for America's ...? The NREL does a fine job publishing theoretical studies. However, the value of these studies is unknown. Do they lead us in the right direction or not? A few years back they published a four-volume study suggesting that 80% of the United States grid could, in theory, be renewable by 2050. What were the ramifications of that study other than to convince the citizens of California that it was OK to close nuclear power (with an attendant rise in emissions)?

One piece of their work that I have personally found valuable is their website to help you calculate the value of solar panels on your roof. I used it for my house and found that I would be $30,000 poorer over the life of the panels if I installed them. The website is just a little deceptive in that they stop short of calculating your total gain or loss for you. You have to be smart enough to figure that out for yourself. All it does is estimate what your panel energy would be worth in cents per kWh. You have to understand what this means, multiply it times the kWh you would use over the life of the panels and compare it to what you would have spent without the panels.

Now why would they stop short like that if they were not trying to prevent sticker shock?

As I said in an earlier article, being "renewable" is irrelevant to fighting climate change. Our energy sources need two qualities:
1) Low emission
2) Affordable at scale
Renewability is a sufficient but not necessary condition for reducing carbon emissions except in cases where renewable sources are not low carbon (some biofuels).

The best bet for future low carbon grids will be a mix of nuclear and renewables with just enough natural gas to stitch them all together.

Credit puzzle graphic: David Goehring via Flickr Creative Commons

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