P.J. Meier, J. Erickson, J. Mapp, Measuring Emission Benefits with Integrated Resource Models - Why Simple Estimates of Emission Reductions May Be Wrong. In Production. Proceedings of the International Energy Program Evaluation Conference (IEPEC), 2005.

Abstract

Energy efficiency program administrators must account for the emissions displaced by their programs in order to accurately report achieved benefits. This paper examines three methods of calculating those displaced emissions. Emission reductions from three demand-side technologies were calculated with integrated resource models, capturing the hourly changes in power plant emission rates and end-use technology performance. Refined load shapes were developed to characterize the time-of-use for residential CFLs, commercial office building CFLs, and residential air-conditioning. Those load shapes were used within the integrated resource models to calculate refined emissions estimates. Results of the rigorous modeling were compared to estimates using flat load shapes (neglecting time-of-use) and estimates using system-average emission rates. Using system-average emission rates was shown to be highly inaccurate. Neglecting time-of-use also resulted in significant relative errors that varied with technology, pollutant, and supply-side system. Errors are lower for a system that consistently relies on a single fuel, because a poor characterization will still displace the correct fuel. Errors are considerably higher for systems that more frequently alternate between marginal fuels. In systems alternating between coal and natural gas, the error will be lowest for CO2 and higher for SO2, NOx, and mercury. Errors when end-use load shape is neglected were as high as 17% for CO2 and 180% for mercury. These results have bearing on policies that promote certifiable DSM emission reductions. Emission reduction estimates that neglect the hourly changes in marginal emission rates and the end-use technology’s time-of-use are often inaccurate and occasionally invalid.

The full text of this paper is available at www.iepec.org

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