How ComEd Used Distributed Generation To Handle Its Peak Summer Load

Commonwealth Edison Company (ComEd-A Unicom Company)serves more than 3.4 million customers across Northern Illinois, or 70percent of the state’s population. The summer of 2000 marks the thirdconsecutive year that ComEd used diesel generation for peak shaving,distributed generation, in the Chicago area.It began back in 1997, when the effects of El Niño forecast in-creased temperatures throughout the nation. Research began to deter-mine what alternatives existed to provide extra power capacity on atemporary basis. After reviewing data from portable diesel generatorsuppliers, it was determined that is was feasible to supply generation onan as needed basis.With that, a plan was put into place to provide temporary, regionaldistributed generation to critical areas in the territory. ComEd contractedto rent 90 megawatt’s of portable diesel generation during the months ofJune through August. Although the running hours were limited, theproject was viewed as a success. This success shed light as to the pos-sibilities of providing a quick and cost effective means of local, peakshaving generation.In 1998, ComEd researched the market for temporary power alter-natives. Areas that were covered included, power barges, 3-5MW dieselson railcars, and small jet turbines. Once again the diesels won out andwere contracted for the project. Only this time, the scope was raised to210MWs.