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Liberty Time-of-Use-Storage Pilot: A Glimpse into the Future of Energy

Henry Herndon

Energy storage is coming to New Hampshire! Well, at least for a small subset of Liberty Utilities electric customers.

In January 2019, Liberty Utilities received approval from the New Hampshire Public Utilities Commission to roll out a cutting-edge energy storage program for selected residential customers. Over the coming year, Liberty will install and own between 100 and 200 Tesla Powerwall battery packs in residential homes.

What makes this storage program especially innovative is the accompanying time-of-use rate that each participating customer will enroll in. The time-of-use rates send a price signal to the batteries, directing them to shift energy consumption away from times of high cost to times of low cost. Under the new rates, customers will charge their batteries overnight at about $0.07 per kilowatt-hour (kWh), less than half the typical price of electricity. Then, between 3pm and 8pm, prices jump up to approximately $0.36 per kWh, roughly double typical pricing. During these “critical peak periods” when demand for energy is high, the battery will power the customer’s home and the customer can avoid drawing expensive power from the electricity grid. Table 1 shows the complete rate design.

Table 1 – Illustrative Time-of-Use Rate

8pm-8am (Off-Peak) 8am-3pm (Mid-Peak) 3pm-8pm (Critical Peak)
Energy Supply $0.03/kWh $0.08/kWh $0.15/kWh
Transmission $0.01/kWh $0.02/kWh $0.13/kWh
Distribution $0.03/kWh $0.05/kWh $0.08/kWh
Total $0.07/kWh $0.15/kWh $0.36/kWh

As a result of this kind of storage-enabled load shifting, customers can save money by buying cheaper, off-peak power, and Liberty Utilities can save money by reducing stress on the system when demand for energy is high. This saves money for all Liberty Utilities customers, not only those with home batteries!

The program gets even more interesting for participating customers with solar-powered homes. Customers with solar arrays can use the sun to charge up their batteries. Then, when the 3pm-8pm critical peak comes around, excess solar can be exported to the grid when it needs energy the most. Think of this as a better way deploy solar as a grid resource. It’s called “dispatchable solar” because the battery allows for solar energy to be dispatched on command.

Graph developed by Henry Herndon.

Graph developed by Henry Herndon.

While the Liberty Utilities Pilot is for residential customers only, New Hampshire’s other electric utilities have plans to achieve similar demand reduction goals. As part of their NHSaves energy efficiency program offerings, Eversource and Unitil will be committing $343,765 toward developing “demand reduction initiatives” for their commercial and industrial customers. These pilots will not necessarily involve energy storage and time-of-use pricing, but the goal is the same: reward energy users for shifting consumption to times of low cost.

Efforts to reduce energy costs with energy storage, load shifting, and creative policy approaches are spreading across New England. Massachusetts recently became the first state to make energy storage an eligible technology to receive energy efficiency funding through Mass Saves, the counterpart to NHSaves energy efficiency programs in New Hampshire.

The Liberty Storage Pilot may be small, but it is significant. If Liberty’s approach proves successful, the program will be expanded to allow for competitive market actors to provide energy storage solutions to customers who wish to take advantage time-of-use pricing. This essentially means you could “bring your own” energy storage system to participate in the program instead of Liberty owning your battery. The pilot gives us a glimpse into the future of the electric grid, and it is looking good for customers who want innovative solutions to their energy challenges.

Henry Herndon is Director of Local Energy Solutions for Clean Energy NH. He works with municipalities across New Hampshire to implement energy efficiency and renewable energy projects to lower community energy costs and advance the goals of sustainability.

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