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.

In addition to energy generated by large facilities, Massachusetts also allows excess energy generated by small-scale, distributed systems to be purchased by utilities (for up to 3% of their peak load) and fed back into the grid. This is known as “net metering.” When the system owner is consuming energy, their electricity meter spins forward. When they are producing energy for the grid, the meter spins backward. At the end of the month, they are only charged for their net energy consumption (their total consumption minus their energy production). If they produce more energy than they consume in a given billing period, they will receive credit for the excess energy they produced but did not use. Read more.

Hydroelectric power is generated by capturing the kinetic energy or motion in free-flowing or falling water, waves, currents or tides, and converting it into electric current. The Massachusetts Class I Renewable Portfolio Standard (RPS) differentiates between hydroelectric power, which captures energy from flowing freshwater with or without the use of a dam structure; ocean thermal, wave or tidal energy, which is strictly derived from marine resources including differentials in ocean water temperatures (“ocean thermal”); and marine or hydrokinetic energy, which encompasses both categories but excludes facilities that dam or impound the flow of water. Read more.