Electricity suppliers in the New England grid generate primarily from fossil fuel and nuclear power resources. However, electricity produced from renewable sources is beginning to gain clout in the market. In Massachusetts, utilities are subject to a renewable portfolio standard (RPS) that requires them to supply a certain percentage of their electricity from renewable or alternative sources.
As of 2013, the requirement for Class I Renewable Generation—energy generated from wind, solar, small hydro, geothermal, biomass, methane digester, or hydrokinetic units that began commercial operation after 1997—is 8%. The RPS also incentivizes the continued operation of qualified pre-1998 renewable generation units by setting requirements for Class II Renewable Generation and provides funding for waste energy programs by setting requirements for Class II Waste Energy Generation. The Green Communities Act of 2008 provided further encouragement for alternative, non-renewable energy sources—such as combined heat and power, flywheel storage, coal gasification, and efficient steam technologies—by setting an Alternative Energy Portfolio Standard (APS), as well.