Northfield Mountain (hydroelectricity facility)

Northfield Mountain is a pumped-storage hydroelectricity facility located in Northfield, Massachusetts. Owned and operated by FirstLight Power Resources, it's a significant source of flexible power generation in the New England region. The facility consists of a reservoir atop Northfield Mountain, a network of tunnels, and a power plant located on the Connecticut River.

The primary function of Northfield Mountain is to store energy during periods of low demand and release it during periods of high demand. Water is pumped from the Connecticut River to the mountaintop reservoir during off-peak hours, typically at night, using reversible pump-turbine units. During peak demand, the water is released back through the turbines, generating electricity as it flows back into the river.

This process provides a form of energy storage, allowing for the efficient utilization of base-load power plants, such as nuclear or coal-fired plants, which operate most efficiently at a constant output. By absorbing excess energy during low demand, Northfield Mountain helps stabilize the power grid and reduces the need for peaking power plants, which are often less efficient and more polluting.

The facility has a generating capacity of approximately 1,080 megawatts. Environmental considerations are a key aspect of the operation, with measures in place to minimize impacts on the Connecticut River ecosystem. These include monitoring water quality, regulating flow rates, and managing fish populations. The operation of Northfield Mountain is subject to regulatory oversight by agencies such as the Federal Energy Regulatory Commission (FERC).