Low water levels in the United States caused significant economic losses for hydropower and increased emissions as natural gas plants fired up to fill the power supply gap, concludes a new study highlighting hydropower’s vulnerability to drought.
“Through our analysis, we estimated that the U.S. potentially incurred a loss of approximately US$28 billion in the hydroelectricity sector due to drought between 2003 and 2020, 50% of which has incurred in the Western U.S.,” write researchers from the Center for Complex Hydrosystems Research at the University of Alabama.
The hydroelectricity decline led to an overall drop of about 300 megawatt-hours generated, particularly affecting the states of California, Washington, and Oregon, where economic losses exceeded $8.7 billion, $4.2 billion, and $1.6 billion, respectively.
The hydropower losses also led to additional emissions, say the analysts, as fossil fuels—particularly gas—were used to fill the gap. Carbon dioxide increased by 10.2%, sulfur dioxide by 0.15%, and nitrogen oxide by 24.48%.
“While the short-term increase in emissions due to drought may not seem alarming on its own, it is crucial to consider the cumulative impact of future droughts on the environment,” the researchers caution.
The study analyzed streamflow data from hydroelectric stations across the contiguous U.S. to evaluate drought conditions through the 18-year period. Then the researchers measured the resulting drought patterns against hydroelectric generation to determine how the two correlated.
The study established a correlation between drought and hydroelectricity generation in the U.S., with 95% confidence for all states except Arizona, Colorado, Illinois, Nebraska, and Nevada. Further analysis with other datasets brought in facility-level data for approximately 1,400 power plants in the region, along with monthly retail electricity prices and emission intensities.
Several factors affected drought vulnerability in various states, like over-year water storage in upstream reservoirs and soil moisture. Certain trends made economic impacts particularly severe in some states, like in Oregon, Washington, and California, where droughts were particularly severe and frequent. Rhode Island, Kansas, New Jersey, and Illinois had comparatively lower economic impacts because they produced less hydropower and had fewer droughts.
The study is geared toward energy policy-makers, planners, and academics, with an aim to “inform policies and practices related to drought management and energy production” as drought is expected to become more frequent and intense due to climate change, write the authors.
They recommend that state governments form regional or interstate energy networks to leverage “each other’s strengths in renewable energy sources and energy storage capacities,” and urged states to “prioritize policies and incentives that promote energy efficiency and conservation.”
