Power Supply Portfolio

The Hingham Municipal Lighting Plant provides electricity to approximately 10,000 customers in Hingham. Energy New England (ENE) manages HMLP’s Power Supply Portfolio.

About HMLP’s Power Supply Portfolio

HMLP supplies the customer load in Hingham by entering into long-term and short-term contracts. These contracts differ in duration depending on the need, price, and agreement terms. When the market price for energy falls below that of HMLP’s contracts, HMLP buys a portion of its power from the day-ahead energy market. Other times that HMLP may buy from the open market are when generator outages occur or when HMLP needs additional supply to meet increased load.

HMLP continually manages its mix of power supply contracts (its portfolio) to ensure diversity in fuels, generator types, and suppliers. It also continuously monitors costs and contingencies to mitigate risk and provide price stability for Hingham customers. Per HMLP’s mission statement, we are always looking for competitively priced non-carbon-producing sources of electricity to meet our long-term goal of a carbon-emissions-free power supply.

To learn more about HMLP’s portfolio, watch our Light Board meeting from June 6, 2023, where Energy New England (ENE) presented and answered questions.

What portion of HMLP’s power supply is carbon-free?

Nuclear Energy is wholly carbon-free

HMLP’s power portfolio changes over time. Long-term contracts with nuclear generators are represented in blue in the pie chart below.

System Power is an unknown mix of fuel

A portion of HMLP’s power supply is purchased on the open market. This portion of the power supply is most likely fossil-fuel-based because it is a mix of whatever is available on the market. As more renewable energy joins the energy market, the mix of this supply will become more carbon-emissions-free. However, it is impossible to know this energy’s emissions-free content at any given moment. This portion of HMLP’s power supply is represented in yellow and brown on the pie chart.

Landfill Gas is wholly carbon-free

Landfill gas is methane captured from landfill off-gassing. It would otherwise be released into the atmosphere if it wasn’t burned for energy.

Wind, Solar, and Hydroelectric Energy is wholly carbon-free, but HMLP cannot claim all of it as “renewable

The remainder of HMLP’s power supply is contracted from wind, solar, and hydroelectric energy generators. These contracts are represented in green on the graph below.  Of the energy these generators supply, a percentage comes with Class 1 Renewable Energy Credits (RECs).  Owning the REC for a kilowatt-hour of this electricity allows the credit owner to claim legally that this kilowatt hour of energy is “renewable.” HMLP does not retain the RECs that come with the power it buys. 


Renewable Energy Credits (RECs)

HMLP sells its RECs on a market where sellers of fossil-fuel energy purchase them to serve as offsets for their fossil fuel use. The owners of the RECs can claim credit for the renewability of that energy as part of their portfolio.  When HMLP sells the RECs that come packaged with energy, HMLP cannot claim that this energy is renewable; the right to do that has been sold to someone else.  For more information, see HMLP’s Power Supply Policy

Some of the energy from these generators comes packaged with other kinds of RECs, which don’t meet the state’s requirements for calling the energy “renewable.” However, the power comes from wind, solar, or hydropower. The state’s regulations favor new development of renewable energy, and often, the other kinds of credits are for older installations. 

2022 & 2023 Resource Energy & REC Cost

2023 Power Supply Portfolio



Stony Brook Peaking


Stony Brook Intermed.


Comm. New Bedford Landfill


NextEra Energy (HUB & SEMA)


Shell Energy


ISO Energy Interchange


NextEra (Seabrook) - Nuclear


Seabrook - Nuclear


Millstone 3


NYPA (Hydro)


W Hingham & Nantasket Solar


Brown Bear (Miller/Worumba) Hydro


First Light Power Resource (Hydro)


Spruce Mountain Wind


Saddleback Ridge Wind, LLC


Canton Mountain Wind, LLC


Granite Rel. Pwr, LLC Wind (HUB)


Rox Wind LLC


NuGen-Harrington St. PV


Total Non-Fossil Fuel


Total Non-Fossil Fuel (excl. nuc. & landfill)




System Power under Contract


Landfill Gas


Fossil Fuel