Giant battery, utility control of some customer thermostats part of Eversource plan 

Monitor staff
Published: 5/21/2019 5:11:52 PM

Eversource is looking for permission to control some customers’ thermostats, electric vehicles or home batteries on hot afternoons as a potential alternative to expensive and polluting upgrades to the power grid.

The company is expected to make an application for the program this summer, following a related proposal coming this month that would use thermostat control, along with a giant battery and energy-efficiency programs, to do the job of a $6 million electric-line upgrade for a small New Hampshire town.

“The idea is to have lower net cost than a traditional line,” said Charlotte Ancel, Director of Clean Energy Strategy for the state’s largest electric utility.

The two proposals, which must be approved by the Public Utilities Commission, fit into a category with the inelegant name of “non-wires alternatives.” These involve improving the grid by installing battery backup, using distributed energy from solar panels and coordinating real-time reduction of customer demand. Such programs are often seen as key to keeping the lights on as we try to contain climate change and take advantage of solar and wind power.

Liberty Utilities is rolling out its own non-wires alternative on a pilot scale and Green Mountain Power in Vermont started one two years ago. Unlike those utilities, Eversource does not want to own any of the home batteries or thermostats that customers would volunteer to enroll in the program, but will operate only on a “bring-your-own-device” program. Eversource in Massachusetts will be starting a similar program involving customer-owned devices in July.

Eversource’s first proposal, which it announced Tuesday, involves Westmoreland, a town of about 1,800 on the Connecticut River west of Keene. The town is served by a single distribution line and its tree-filled streets are prone to line-disrupting storm damage.

“It has had some of the worst reliability characteristics in our service territory – over 20 outages over the last five years, with the average duration 2½ hours,” said Ancel.

The traditional solution, she said, would be to build a second distribution line as backup, running 10 miles from Keene, at a cost of about $6 million.

Instead, Eversource is proposing to build a 7.1-megawatt lithium-ion battery system that could provide backup power to the entire town “for about four hours” at peak usage.

While that battery would cost more than the power line, an estimated $7 million, it can be used for what is known as peak-shaving, or shaving down the amount of power that Eversource needs to buy from power plants during peak periods such as a hot summer afternoon when everybody’s air conditioning is running. This peak power is very expensive and often produced by the most polluting of power plants, so trimming even a bit of it can produce big savings.

Ancel said Eversource estimated that the battery’s peak-shaving ability would cover its costs and generate about $2 million over its lifetime.

Peak shaving is also the point of Eversource’s proposed program for 45 customers to volunteer to give the company control of devices such as thermostats and electric-car chargers. Eversource would want to reduce their demand at peak periods by, for example, slightly raising the temperature in a home during that summer afternoon.

A separate proposal that Eversource plans to file this summer would ask permission to set up a bring-your-own-device program throughout the state, on a customer volunteer basis.

The PUC must approve these programs because the costs and benefits can affect everybody’s electric rates.

In Vermont, Green Mountain Power claims that its home-battery program saved it some $600,000 during peak periods last summer and is experimenting with controlling the temperature in electric water heaters as another distributed battery.

The third component of Eversource’s Westmoreland plan is a town-wide energy efficiency push to reduce the total amount of electricity needed at any time.

Eversource plans to submit this program, called the Westmoreland Clean Innovation Project, to the Public Utilities Commission later this month, Ancel said. If it is approved, Eversource would start targeting the town for efficiency efforts and controlled devices next year and would have the battery in operation by the second half of 2021.

The battery would take up less than an acre and would not require any other major upgrades to hook into the grid, Ancel said.

(David Brooks can be reached at 369-3313 or dbrooks@cmonitor.com or on Twitter @GraniteGeek.)


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