Solar and wind power are amazing resources. They are free and renewable, but they also rely on natural processes that are beyond human control. While it’s important to recognize the potential risks of renewable energy, such as the sun not always shining and the wind not always blowing, have you ever wondered what happens when both of these energy sources are unavailable at the same time?
This scenario is known as a compound energy drought. The researchers at the Pacific Northwest National Laboratory (PNNL) have discovered that in some parts of the country, these energy droughts can last for almost a week.
“It’s crucial for grid operators to be aware of when energy droughts will occur so they can be prepared to secure energy from alternative sources,” said Cameron Bracken, lead author of the paper and an Earth scientist at PNNL. Understanding the geographic areas, timing, and duration of energy droughts will also assist experts in managing grid-level battery systems that can store enough electricity to deploy during times when energy is needed most.
The team’s findings were published in the journal Renewable Energy on October 31 and will be presented at the annual meeting of the American Geophysical Union this week.
In the past, researchers had only studied compound energy droughts on a state or regional scale, but now the PNNL team has looked at the risk of energy droughts across the entire continental U.S. To better understand these risks, the researchers analyzed weather data and historical energy demand data to assess the frequency of energy droughts during times of peak demand.
The researchers examined 4 decades of hourly weather data for the continental U.S., focusing on areas where solar and wind energy plants operate. They found that stagnant air and cloudy skies led to reduced energy generation from these plants, resulting in a compound energy drought.
“We took a snapshot of the current infrastructure as of 2020 and ran it through 40 years of weather data, starting in 1980,” Bracken explained. “This allowed us to assess how the current infrastructure would have performed under historical weather conditions.”
The study revealed that energy droughts can occur in any season across the country, with varying frequencies and durations. For example, in California, cloudy and windless conditions may last several days, while in Texas, these conditions might last for only a few hours. Utah, Colorado, and Kansas experience frequent energy droughts across several-hour and several-day timescales. In contrast, the Pacific Northwest and Northeast seem to experience shorter, more frequent energy droughts.