Power Supply Portfolio

A secure power supply requires planned and targeted resilience. 

RMLD intentionally diversifies its power supply to strengthen the resilience of the grid and to fulfill the non-carbon mandate set forth by the Commonwealth. By contracting power from a variety of sources and suppliers, RMLD is able to mitigate supply risk and progress the non-carbon transition. Through innovative energy strategies and proactive resource management, including energy storage, in-territory generation, and continued strategic partnerships, RMLD has exceeded the current Massachusetts energy mandate and is on track to continue to do so. 

Power Supply Sources

Power Source
MWH
Nuclear
264,439
Hydro
200,485 
Mixed
135,003
Wind
26,793
LFG
11,800
Gas/Oil
​9,564 
Solar
​6,340


2024 Purchased Power By Resource Type

Powering up for the future at RMLD.    

By embracing non-carbon technologies and investing in ‘in-territory’ solutions, RMLD is building a future where low-cost, reliable, and non-carbon power isn’t just possible—it’s reality. 

The Massachusetts 2021 Climate Bill requires RMLD to maintain a certain percentage of non-carbon power in its supply mix. This percentage increases each year, eventually reaching 50% non-carbon in 2030 and 100% in 2050. RMLD has consistently exceeded these guidelines, surpassing the 2030 requirement in 2024—six years ahead of the state mandate—with a 55% non-carbon power supply. 

RMLD purchases associated certificates alongside energy. This approach allows RMLD to sell excess certificates to reduce net energy costs. In 2024 RMLD sold $3,372,496, representing 12 months of generation. These funds go directly towards lowering costs for RMLD customers.

Retired Certificates as a proportion of KWh SALES

Retired Certificates as a proportion of KWh SALES

Massachusetts Climate Law Compliance

The Massachusetts Climate Law establishes compliance standards for municipal light plants (MLPs). This legislation requires that the power sold by MLPs be sourced from resources that are 50% non-carbon by 2030, 75% non-carbon by 2040, and net-zero carbon by 2050. To be considered a non-carbon resource under the Climate Law, the associated energy certificates (renewable or non-carbon) must be retired by the utility. Sold certificates do not count toward Climate Law compliance.

In the context of the Climate Law passage, RMLD revised its Policy 30 to ensure compliance and also minimize rate shock to RMLD customers. Specifically, RMLD will retire certificates up to the annualized line and sell certificates above the line. The least expensive certificates will be retired first. Certificate transactions will be published quarterly, and compliance reports submitted annually.

While the next compliance goal in the Climate Law is not until 2030 (50% non-carbon up from 20% non-carbon in 2020), the annualized line of percentage certificate requirements increases 3% per year, to minimize rate shock.

Power Supply Definitions

  • Mixed Sources - Contracts for non-specific power supply sources and real-time spot market purchases. These reflect the fuel mix of the New England grid and are assumed to be primarily carbon-emitting, such as natural gas.
  • Solar and Wind Sources - Non-carbon-emitting sources that are eligible for Renewable Energy Certificates.
  • Hydro and Nuclear Sources - Non-carbon emitting sources that are eligible for Non-Carbon Energy Certificates.
  • Climate Law - Massachusetts climate legislation which requires that the power sold by utilities be sourced from resources that are 50% non-carbon by 2030, 75% non-carbon by 2040, and net-zero carbon by 2050. To be considered a non-carbon resource, the associated renewable energy certificates must be retired by the utility.