Green Municipal Aggregation Toolkit: Support Renewable Energy

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Use MAPC's Updated Green Municipal Aggregation Toolkit to Support Renewables in Your City or Town

In 2014, MAPC pioneered an exciting model for green municipal aggregation (GMA). For more than five years, we have worked with communities to adopt, deploy, and support GMA. Municipal aggregation, also known as community choice aggregation, allows a city or town to determine where its electricity comes from. In a GMA program, a municipality sources electricity from renewable sources, creating demand for the construction of new renewable energy in New England and lowering greenhouse gas (GHG) emissions. GMA is one of the most effective methods within a municipality’s direct control to lower GHG emissions and help meet climate goals.

We are excited to share that an updated version of our “Start a Green Municipal Aggregation Program” toolkit is now live.
Read the toolkit for:

  • Background on GMA
  • Detailed steps and timeline for starting a GMA program in your municipality
  • Assessment of the benefits and risks of GMA
  • Data on pricing in Massachusetts municipalities that have adopted GMA
  • Information on existing GMA models and emerging models that support higher levels of renewable energy

GMA is enabled by Massachusetts state law (MGL c.164§134), which allows electric utility customers to select a supplier other than their utility. Through aggregation, a municipality chooses an electricity supply for the entire community. Residents and businesses who have not already selected a competitive supplier are switched into the program automatically, with the option to opt-out at any time. The utility still provides customer electric bills and program participants will just see a different name and rate on the supply portion of their bills.

GMA programs bring many advantages. They are typically able to offer lower prices and better price stability than the utility’s basic service. The programs also offer protection from predatory brokers attempting to sell residents misleading energy contracts directly. From a climate perspective, GMA programs are an important driver of renewable energy on the grid. Green aggregation programs are structured to include a higher percentage of renewable energy than the utility’s basic service offering. This structure drives demand for new renewable energy to be added to the electric grid.

In the MAPC region, at least 29 municipalities have authorized or are running active GMA programs that require at least five percentage points more renewable energy sourced from within New England than the minimum required by the state. This represents a percent increase in renewable energy of more than 30 percent in each of these communities. Some communities are experimenting with new models to add more renewable energy to the grid. The City of Cambridge’s program, for example, raises funds to build local renewable energy projects while still maintaining a competitive price by using an “operational adder.” With an operational adder, a municipality receives a fee from the supplier that can be dedicated to funding energy efficiency or renewable projects.

Over half of the households in MAPC’s region are part of GMA programs and we would like to help that number grow further. MAPC’s staff can provide guidance, resources, and technical assistance to our communities on how to start a GMA program or renew an existing program. MAPC can help your community design a program that increases the percentage of renewable energy in your supply, builds local renewables, or pursues other innovative models to meet your community’s climate and clean energy goals. Please contact Julie Curti at for assistance and visit our website and toolkit on GMA for more information