This excerpt taken from the NRG 10-Q filed Oct 30, 2008.
Regional Environmental Initiatives
Northeast Region On December 20, 2005, 10 northeastern states entered into a Memorandum of Understanding, or MOU, to create the Regional Greenhouse Gas Initiative, or RGGI, to establish a cap-and-trade GHG program for electric generators. Electric generating units in participating RGGI states will have to procure one allowance for every US ton of CO2 emitted with true up for 2009-2011 occurring in 2012. NRG units located in Connecticut, Delaware, Maryland, Massachusetts and New York emitted approximately 13 million US tons of CO2 in 2007. NRG believes that to the extent allowance costs will not be fully reflected in wholesale electricity prices, the direct financial impact on the Company is likely to be negative as costs are incurred to secure the necessary RGGI allowances and offsets at auction and in the market.