The Arlington Community Electricity program presents a unique opportunity for the Town to influence the development of renewable energy resources by going above and beyond the requirements of Massachusetts – this means voluntarily purchasing additional renewable energy. See the Massachusetts renewable energy requirements.
In Arlington Community Electricity, all purchases of renewable electricity are certified by purchasing and retiring Renewable Energy Certificates (RECs), the accepted legal instrument used to track renewable energy generation and to substantiate claims of renewable energy use. Read more about why we need RECs.
Sourcing the Additional Renewable Energy
On Our Grid
All of the additional renewable energy in the ACE Program will come from sources designated as MA Class I. These sources must be physically part of our New England electricity grid. This stands in contrast to some electricity supplies that obtain their renewable energy from national sources (e.g., Texas) that are not physically connected to our New England electricity grid. While those sources provide very cheap electricity, you get what you pay for; including them in the electricity mix does not move our region away from fossil fuels.
MA Class I is the Massachusetts term for new, local renewable energy. The renewable energy can come from the sources shown in the figure below and must:
- Have started operation after 1997
- Be located within New England, New York or Eastern Canada
2022 Sources of MA Class I for RPS Compliance
Helping to Build Clean Energy
Massachusetts requires all energy suppliers to include a minimum amount of MA Class I renewable energy that increases annually. If the supplier does not meet these requirements, the supplier is required to pay a penalty. This policy, called the Renewable Portfolio Standard, provides growing demand for renewable energy, which incentivizes new renewable generation facilities to be built. By purchasing a significant quantity of extra MA Class I renewable energy, Arlington is incentivizing even more renewable energy generation development in New England.
How big is our impact?
As of August 2025, ACE customers have purchased an extra 61,544 MWh of MA Class I renewable energy, above and beyond state requirements. This avoids approximately 43,942,416 lbs of CO2 emissions. Sign up your home.
What Are RECs and Why We Need Them
When electricity generated by renewable sources – such as solar and wind – is put onto our regional electricity grid, it becomes mixed in with and indistinguishable from the other electricity on the grid. It is not possible to physically separate out renewable electricity from the grid mix for your individual consumption.
As a result, a tracking system, called Renewable Energy Certificates (RECs), has been created to enable the purchase and use of renewable electricity. For every one megawatt-hour of renewable electricity generated, one REC is created. In order to use renewable electricity, one must purchase a quantity of RECs equal to the amount of electricity purchased from the grid. Once used, a REC is retired so that no one else can purchase that same REC or claim to use it.
1Hydro projects that do not exceed 30 MW built after 1997 or have capacity additions or efficiency improvements made after 1997 (MA Class I eligible), and Low Impact Hydro Institute (LIHI) certified.
2Methane has a global warming potential (GWP) 28-36 times greater than CO2 over a 100 year period. Combustion destroys methane and releases some CO2, resulting in a net reduction in GWP. For more, see Environmental Protection Agency, Understanding Global Warming Potentials.