California achieves on average about 15 percent of its electricity generation from hydropower, with 75 percent of this hydroelectricity coming from stations at high elevations. However, as the climate changes, the amount of water storage these stations are capable of will diminish as precipitation turns from snow into rain, affecting the state in summer when it needs these hydro stations the most.
In short, California’s hydropower is specifically vulnerable to climate change.
These are the findings of a report released July 31 by the California Natural Resource Agency and the California Energy Commission, and led by Kaveh Madani, a former postdoctoral research scholar in UC Riverside’s Water Science and Policy Center who is now currently an assistant professor of civil, environmental, and construction engineering at the University of Central Florida.
“Climate change is expected to affect the quantity and timing of water flow in the state,” Madani said. “Under dry climate warming, the state will receive less precipitation, with most of it as rain instead of snow, impacting hydropower supply and operations.”
The problem is that of the more than 150 high-elevation units, most of which are located in Northern California and the Sierra Mountains, the majority are not built for their storage capacity, focusing rather on hydroelectricity production and not other benefits such as water supply and flood control.
“If California loses snowpack under climate warming, these high-elevation reservoirs might not be able to store enough water for hydropower generation in summer months when the demand is much higher and hydropower is priced higher,” said Madani. “California might, therefore, lose hydropower in warmer months and hydropower operators may lose considerable revenues.”
Madani, who led UCR’s only research team for CEC’s third climate change assessment studies, explained that the major cause of revenue loss is that hydropower prices are expected to decrease in colder months of the year and increase in warmer months.
“The big problem is that hydropower will be less available when it is most needed and expensive: in the summer months,” he said. “A warmer California needs more electricity for cooling in summer months and less electricity for warming in winter months. This means that hydropower pricing patterns will be affected by climate change. It is important to analyze climate change effects on this renewable energy source early on to figure out what strategies are available to adapt to the new conditions and thereby minimize the potential negative impacts of climate change on hydropower.”
Madani explained that, on average, California could lose up to 20 percent of its hydropower generation under dry climate change, which can result in 8 to 18 percent reduction in hydropower revenues for producers.
“Our results do not yet suggest that we need to build more dams in California for hydropower generation,” said Madani, who was recently selected as one of the 10 New Faces of Civil Engineering in 2012 by the American Society of Civil Engineering. “But they suggest that hydropower, a highly valuable energy source, may be less available. So we have to look for clean replacements and we have to reduce our energy demands as much as we can.”
Madani’s focus on the effects climate change is having on California’s hydropower began when he was a graduate student at UC Davis, where he helped develop an “Energy-Based Hydropower Optimization Model” (EBHOM) that covers more than 150 high-elevation hydropower units in California which helps prescribe the best operation policies in response to the changes in climatic conditions.
Madani developed a new version of the model that can estimate changes in hydropower pricing and demand in response to temperature changes.
“It helps us consider the effects on supply and demand simultaneously,” Madani said of the model’s new version. “But modeling studies have limitations that need to be addressed as more data become available and the science improves. Future studies need to have a closer look at the environmental side of this problem. Changes in operations of the high-elevation systems should be done after careful consideration of all possible environmental damages.”
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