How ComEd Used Distributed Generation To Handle Its Peak Summer Load

Abstract

Commonwealth Edison Company (ComEd-A Unicom Company)
serves more than 3.4 million customers across Northern Illinois, or 70
percent of the state’s population. The summer of 2000 marks the third
consecutive 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 a
temporary basis. After reviewing data from portable diesel generator
suppliers, it was determined that is was feasible to supply generation on
an as needed basis.
With that, a plan was put into place to provide temporary, regional
distributed generation to critical areas in the territory. ComEd contracted
to rent 90 megawatt’s of portable diesel generation during the months of
June through August. Although the running hours were limited, the
project was viewed as a success. This success shed light as to the pos-
sibilities of providing a quick and cost effective means of local, peak
shaving generation.
In 1998, ComEd researched the market for temporary power alter-
natives. Areas that were covered included, power barges, 3-5MW diesels
on railcars, and small jet turbines. Once again the diesels won out and
were contracted for the project. Only this time, the scope was raised to
210MWs.