The New York Times:

Exelon, the electric company based in Chicago, will promise on Tuesday to cut greenhouse gas emissions by 2020 by an amount larger than its total emissions in 2008, in a bid to shape the debate on carbon dioxide rules and to get a jump on compliance…

The reductions in greenhouse gas emissions will come by making Exelon’s operations more efficient, cutting the energy use of its electricity customers and building low-carbon generators that would displace older, less-efficient plants, many operated by rivals, the company said.