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  The Impact of EPA's Green Power Purchases (45 pp, 560 KB) (EPA/600/R-07/019) March 2007

All federal agencies, including EPA, are required under Executive Order (EO) 13123 to reduce life-cycle greenhouse gas emissions attributed to facility energy use by 30 percent below 1990 levels by 2010. To reduce facility greenhouse gas emissions, EPA’s Office of Administration and Resources Management uses a key approach that involves the purchase of “green power.”

Green power means using renewable natural resources (wind, solar, biomass) and other clean energy technologies (municipal solid waste and landfill gas) to generate electricity. Green tags, which represent the positive environmental attributes associated with electricity production from green power sources, are sold through markets to electricity consumers.

The analysis presented in this report meets the following three objectives:

  • Establish the 1990 EPA emissions baseline in order to assess progress toward fulfillment of EO 13123
  • Examine the impact of EPA’s green power purchasing on facility-related greenhouse gas emissions and air pollution
  • Develop a strategy for future green power purchases

This report describes a new method to estimate net emissions of carbon dioxide, sulfur dioxide, nitrogen oxide, and mercury. The estimation of net facility emissions is complicated by the purchase of green tags because it requires detailed knowledge of which conventional power plants are being offset by purchased green power. Different offset scenarios are analyzed in order to quantify the uncertainty inherent in estimating emissions offsets without hour-by-hour system dispatch data.


Joseph DeCarolis

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