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Is Intermittency of Renewable Energy a Problem?

Last updated: 01-09-2021

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Is Intermittency of Renewable Energy a Problem?

In a recent post, "How Can We Design For Intermittency of Renewables?," I argued that the problem of intermittency – those times when the sun doesn't shine and the wind doesn't blow – could be solved or dramatically reduced by designing our buildings to act as thermal batteries that could coast through these periods. A commenter pointed out that intermittent was probably the wrong word, and that it should be variable.

It is an important point; the wind is always blowing somewhere. Many people have claimed that if we have more renewables then we have a bigger problem of variability, but in fact, the opposite may be true. A few years ago, Robert Fares of the U.S. Department of Energy Building Technologies Office explained The Law of Large Numbers in Scientific American:

He quotes studies that have shown that the larger amount of renewables, the less one has to worry about the variability and stability of the grid, and the less backup that is needed.

More recently Michael Coren of Quartz reported on the work of Marc Perez, who notes in a published paper that the price of solar has dropped so much that one could overbuild the system to provide enough energy, even on cloudy days.

Given that many electrical systems have other low carbon power sources, like nuclear or hydroelectric to provide a base of constant power, perhaps variability isn't such a big problem.

After reading the earlier post where I quoted Tresidder, he responded with tweets noting that in winter there is a need for long-term storage. He continued:

Perhaps. Hydrogen expert Michael Liebreich responds to Tresidder's tweets, agreeing that we need hydrogen backup as well, but it sure seems like it would require a lot of investment; all these electrolyzers and tanks, new distribution networks, and salt caverns to deal with 0.2% of the time. If those pensioners had proper homes, the electricity needed to keep them warm might be so small that they could borrow a cup of electricity from France or somewhere else where the wind is blowing.

Perhaps I should listen to experts like Tresidder and Leibreich; perhaps things have changed since I developed my aversion to the idea of the hydrogen economy 15 years ago. Back then, it was promoted by the nuclear industry as a way of justifying a massive buildout of nuclear plants that would make enough electrolytic hydrogen to power hydrogen fuel-celled cars and buses. That dream died with Fukushima, but now the hydrogen dream is driven by the oil and gas industries, which are promising "blue" hydrogen made from fossil fuels with carbon capture, utilization, and storage.

But then I am trained as an architect, not an engineer. I remain convinced that the answer is to reduce demand through Passive House level standards of efficiency, more multifamily housing with fewer exterior walls, in walkable communities with fewer cars. Work the demand side of the equation, not the supply side. And just in case, build a better, bigger, international grid; the wind is always blowing somewhere.

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