By Kevin Wilcox
The hot, dry weather projected by midcentury will reduce the capacity of steam and combustion turbine facilities by nearly 9 percent.
Roughly 46 percent of the power-generating capacity in the Western United States and Canada is vulnerable to problems associated with a warming climate by the middle of this century, according to new research. Wikimedia Commons/Hydrogen Iodide
June 2, 2015—The warmer, dryer air and changes to surface waters projected for the U.S. Southwest because of climate change will reduce the capacity of power-generating facilities there by 2040, even as the population—and peak summer energy demand—continue to grow, according to new research by experts at Arizona State University (ASU). The team found that these capacity decreases could be as much as 8.8 percent during drought conditions.
"We are seeing more frequent heat waves in the United States; we are seeing temperatures that are increasing, particularly in the Southwest," says Mikhail V. Chester, Ph.D., an assistant professor of civil, environmental, and sustainable engineering at ASU who is among those leading the research. "What does that mean for electricity generation? Do we really have a grasp of what is going to happen to energy supply because of that?"
To answer these questions, Chester and Matthew Bartos, a research scientist at ASU, employed a mixed-method approach that began with a range of downscaled climatological forecasts through 2040 for the western United States. "We used what we think is a reasonable set of bounding scenarios to capture low-, middle-, and high-carbon emissions futures," Chester says. A hydrological model developed by the University of Washington was then used to project stream flows and stream temperature changes. "We then used thermodynamic models of power plants to estimate the efficiency losses when hotter air or hotter water [is] used in the facility," Chester explains. "The plant has to do more work to generate that kilowatt-hour of electricity. This is the energy penalty associated with climate change."
Chester and Bartos recently published their findings, " Impacts of climate change on electric power supply in the Western United States," in the journal
Nature Climate Change
. They evaluated five different types of facilities—steam turbine, combustion turbine, hydroelectric, wind, and solar photovoltaic—examining how projected changes in stream flow, stream temperature, vapor pressure, ambient air temperature, air density, and wind speed affected generating capacity. They focused on facilities within the Western Electricity Coordinating Council (WECC), the largest of the regional entities comprising the North American Electric Reliability Corporation, a nonprofit regulatory authority whose mission is to assure the reliability of the bulk power system in North America. The WECC oversees systems in the western one-third of the United States and two Canadian provinces.
"Some of the technologies are more susceptible to [climate change] than others," Chester notes. "What we found, in aggregate, is that about 46 percent of generating capacity in the West is vulnerable, which is about 978 electric power stations.
"We found that thermoelectric technologies—steam turbines and combustion turbines—[will] have the largest capacity reductions by midcentury," he continues. "Of those, we found that combustion turbines [have] the most consistent capacity losses on a year-to-year basis." Those capacity losses average about 3.5 percent under normal summer operating conditions in 2040.
The research also indicates that large-scale renewable energy-generating facilities—such as wind farms and solar photovoltaic arrays—experience the lowest levels of capacity loss and will be most consistent over a wider range of changing environmental conditions.
The research indicates that the effects of climate change are varied within the western United States. Electric-generation facilities in the Pacific Northwest, for instance, will likely experience a lesser degree of capacity loss from climate change—and in some scenarios could actually see an increase if increased rainfall boost hydroelectric capacity.
"That raises an interesting question," Chester says. "You have more capacity in one region of the country, less in another. Is there a way to move that capacity from one area to the other reliably? Can we increase transmission capacity between the north and the south despite forecasts that show increased wildfire risk?"
This research, funded by the National Science Foundation, is part of a larger effort to relate infrastructure to the services and benefits it provides. As a next step, Chester plans to more closely assess the specific areas in such major southwestern cities as Los Angeles and Phoenix that might not have access to reliable electricity during a dangerous midcentury heatwave. The next link in that connection is to examine how climate change will impact the capacity of the electricity grid to reliably deliver power to consumers. Hotter temperatures might mean certain transmission and distribution components operate at a lower capacity or break more frequently, for example. The concern, Chester notes, is there may be a cumulative effect.
"Supply, transmission, and demand must be evaluated as a system," Chester says. "A small percentage drop in supply, a small percentage drop in transmission capacity, and a small percentage increase in demand may add up to pressure that the energy system wasn't designed for.
"We're trying to develop the knowledge for civil engineers to be able to see that these vulnerabilities exist, they are coupled, and they have the potential to cascade through the system," he explains. "If we can identify them now, then we could potentially deploy recommendations—what I would call anticipatory management of the system—so that we can reduce vulnerabilities ... before a major failure event happens."