NorthWestern to have energy storage system

The Tyngsborough-based company, a maker of “flywheel” power storage systems, said it will build a 1-megawatt storage system for NorthWestern Energy in Montana, expected to be operational by the end of the year.

The flywheel systems provide frequency regulation service, which helps to stabilize the electric grid by balancing power supply levels during moment-to-moment variations in demand.

Beacon Power has built its other energy storage facilities for grid operators in New York and Massachusetts. The Montana project is “the first tangible result of the second part of our business model, the sale or lease of plants and systems to vertically integrated utilities, i.e., those that must self-provide frequency regulation,” Beacon spokesman Gene Hunt wrote in an email.

NorthWestern Energy will lease the system from Beacon for $500,000 for the first 15 months and for the same amount for future 15-month terms. NorthWestern also has the option to buy the facility for $4 million at any point, Beacon said.

The facility will be located on the site of the Mill Creek Generating Station, a gas-fired regulating reserve plant owned by NorthWestern Energy in Anaconda, Mont.