Understanding the risk of compound energy droughts—times when the sun doesn’t shine and the wind doesn’t blow—will help grid planners understand where energy storage is needed most

JoAnna Wendel, PNNL

Solar and wind power may be free, renewable fuels, but they also depend on natural processes that humans cannot control. It’s one thing to acknowledge the risks that come with renewable energy: the sun doesn’t always shine and the wind doesn’t always blow, but what happens when the grid loses both of these energy sources at the same time?

This phenomenon is known as a compound energy drought. In a new paper, researchers at Pacific Northwest National Laboratory (PNNL) found that in some parts of the country, these energy droughts can last nearly a week.

“When we have a completely decarbonized grid and depend heavily on solar and wind, energy droughts could have huge amounts of impact on the grid,” said Cameron Bracken, an Earth scientist at PNNL and lead author on the paper. Grid operators need to know when energy droughts will occur so they can prepare to pull energy from different sources. On top of that, understanding where, when, and for how long energy droughts occur will help experts manage grid-level battery systems that can store enough electricity to deploy during times when energy is needed most.

The team published the findings October 31 in the journal Renewable Energy and will be presenting at this week’s annual meeting of the American Geophysical Union.

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