Green Municipal Aggregation

MAPC is committed to helping cities and town in the Commonwealth and the nation to develop green municipal aggregation programs that will truly reduce greenhouse gas emissions and fight climate change, as well as provide cost savings and price stability.

Municipal aggregation – also known as community choice aggregation - allows a city or town determine where its electricity comes from. The following page contains background information as well as links to MAPC's Fact Sheet, Case Study and How-To Toolkit for more information.


In a municipal aggreation, a city or town contracts with an electricity supplier on behalf of residents and businesses who have not already selected a competitive supplier. Most residents and businesses currently get electricity supply, referred to as basic service, from their electric utility (e.g., National Grid or Eversource). Under state law, however, electric utility customers can choose an electricity supplier other than their utility, and the utility will continue to deliver the electricity, maintain poles and wires, and provide other customer services. Customers still receive a single electricity bill.

Goals of Aggregation

Typically, most aggregations in Massachusetts have pursued cost savings and price stability as primary goals. Aggregations can purchase for longer periods than the utility, providing more price stability. And aggregations can choose when to purchase, to take advantage of good market condtions.

Some aggregations have also set a goal of purchasing more renewable energy; however, these purchases were unlikely to lead to the construction of new renewable energy.

How MAPC is Greening Aggregation

MAPC, working with the city of Melrose, developed the strategy that can help build new renewable energy, while still maintaining competitive prices and price stability.

Our solution: exceeding the state’s requirements for renewable energy from new projects that are built in our own region. 

Due to the buying power of the aggregation, this 5% adds up across each community and across each aggregation. In total, the MAPC strategy effectively increases the state’s minimum requirement for new renewable energy, helping to build even more renewable generation in our region.

Want more detail on the strategy? Dive into our Case Study for the City of Melrose.


If your community is purchasing extra renewable energy, do you know where it's coming from and whether its having an impact? Contact MAPC for assistance! 

Melrose Success!

Melrose recently finished its first year of implementation of its green municipal aggregation program. Residents saved a total of $200,000 compared to the utility supply rate, and the community's impact could result in a 1-MW wind turbine being built in New England. See our Fact Sheet and Case Study for details.

Get Started! A Program for MAPC Municpalities

MAPC held a competitive selection process for a municipal aggregation consultant who is now eligible to work with any MAPC-member community. The program is caleld Community Electricity Aggregation PLUS.

To form the program, MAPC, the City of Somerville and the Towns of Arlington and Sudbury participated in the selection process, and choose Good Energy, LP. Eight communities in total— Arlington, Brookline, Gloucester, Hamilton, Millis, Somerville, Sudbury, and Winchester—are now enrolled in MAPC’s new program and are in the process of developing their own aggregations.

Contact MAPC ( to find out how to get involved.


  • Case Study on Melrose and MAPC's Community Electricity Aggregation PLUS program: here
  • Fact Sheet (2-pager) on aggregation: here
  • General detailed background on aggregatio: MAPC’s Toolkit here.
  • For a list of municipalities that are implementing aggregation, click here. 
  • Introduction to green municipal aggregation (i.e. CCA) – A 30 minute roundtable discussion led by Carol Oldham, MCAN, with Patrick Roche, MAPC; Mark Sandeen, Sustainable Lexington; and Tommy Vitolo, Synapse Energy Economics.