A new study based on real-world data casts doubt on predictions from model-based studies that rising global temperatures will significantly reduce output from many power stations.
Researchers at Duke University in the United States believe climate warming is likely to cause only minor cuts in energy output at most of the country’s coal or gas-fired infrastructure. Recent studies based on simulation and modelling have suggested rising temperatures will significantly lower the efficiency of cooling systems, with overall plant efficiencies dropping by as much as 1.3 per cent for each 1 degree Celsius of climate warming.
The scientists used hourly temperature and humidity data recorded at National Climatic Data Center stations and US Geological Survey river gauges near 39 US coal or natural-gas-fired power plants over a seven to 14 year period. By correlating this data with plants' hourly heat input and energy output records, they were able to extrapolate how much of output was the result of daily and seasonal variations in temperature.
To ensure a representative sample, the study included both closed-loop and open-loop plants from across the US. Output capacities ranged from less than 500MW up to 3,000MW.
Regardless of location, generating capacity or fuel type, cooling efficiency and energy output was found to be more resilient to climate warming than previous studies have predicted. Plants with closed-loop cooling systems were found to be particularly resilient.
"Our data suggest that drops in efficiency at plants with open-loop, or once-through, cooling systems will be a full order of magnitude smaller than this," said Candise L Henry, a doctoral student at Duke's Nicholas School of the Environment.
Reductions at plants with wet-circulation, or closed-loop, systems may be even smaller, Henry added. "In large part, this is because plant operators are already constantly adjusting operations to optimise plant performance under changing environmental conditions. That's a key consideration the past studies overlooked."
According to Lincoln F Pratson, Semans-Brown Professor of Earth and Ocean Sciences at Duke, the findings provides additional support for section 316b of the US Environmental Protection Agency’s Clean Water Act, which requires most electric generators to install closed-loop recirculating systems.
"The EPA enacted section 316b to protect fish, shellfish and other aquatic animals from being pulled into, and harmed or killed in power plants' cooling water-intake structures," he said. "Our study shows it could also provide the added benefit of helping protect the power plants themselves from the impact of climate warming."
The new findings do not, however, signal an all clear for the power industry, Pratson warned: "The impact of future droughts associated with global warming could still significantly affect plant operations and output by reducing the availability of water for cooling."
Henry and Pratson’s findings are published in the August 2016 issue of Environmental Science & Technology.
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