Sensitivities of Electricity Generation to Climate Change Related Temperature Increases: A Regional Experiment

Monday, May 12, 2014 - 07:00
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As a part of the DOE IARP-supported RIAM project, ORNL undertook an experiment in exploring sensitivities of current thermal electricity generation in one US region to 2050 conditions projected by climate change scenarios, order to illuminate potential stresses on electricity supplies from changes in regional temperature and precipitation. Objectives were to assess the general magnitude of capacity reductions due to projected climate change and to begin to consider patterns of such effects within a region. Such stresses could then be compared with effects of climate change on regional electricity demand, and they could provide one basis for assessing options for electricity system adaptation. For the first time, the experiment combined a downscaled climate change scenario for a US region (ten Southeastern states) with an asset-specific Geographic Information System (GIS) data base on electric power plants and sensitivity curves describing relationships between thermal power plant capacity and air and water temperatures. Sensitivity curves were estimated and validated by comparison with components of the well-established industry model of electric power plant operation. In general, air temperature is the key for gas turbines; in general, intake water temperature is the key issue for steam turbine cycles. Air temperature changes associated with climate change can be drawn directly from climate change scenarios. Water temperature changes, however, are not projected by scenarios. They are affected by air temperatures but also by conditions of the ambient water body: e.g., basin configuration and rate of water flow. For this experiment, water temperature changes were estimated by an approach developed by MIT. An initial experiment has been conducted by arbitrarily selecting one date in summer,2050 to estimate air and water temperatures for the micro-region in which each thermal power plant is located, using the appropriate sensitivity curve to calculate projected capacity reductions compared with (a) the design capacity and (b) the 1950-2000 mean capacity on that date. Combining estimates of reductions of gas and steam turbine operational capacity gives a total reduction of thermal electricity production capacity in the SE, under the assumptions of this experiment. In general, however, the most serious implications of air and water temperatures associated with climate change in the 2050s are potentials for mixing zone restrictions on power plant operations during periods of severe seasonal droughts combined with severe heat waves, which would have the potential to require temporary de-rating of a significant proportion of thermal power generation in parts of the region.