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The largest electric distribution co-op in New England is experimenting with real-time energy rates meant to help members wring more value out of their electric vehicles and battery storage devices.
The New Hampshire Electric Co-op plans to offer members what is called a transactive energy rate as soon as the end of this year. It will essentially enable members to become partners with the co-op, supplying energy from their batteries when it is most needed, and charging up when demand — and prices — are low.
“We recognize that members can provide the resources that we need through their distributed energy resources,” said Brian Callnan, vice president of power resources and access. “We need to create a system that allows them to participate.”
A central goal of the co-op’s strategic plan, the transition to a transactive energy model is key to integrating distributed energy resources into the grid, while also making adoption of the technologies more affordable for members, and increasing system reliability, he said.
Here’s how it will work: The co-op has developed a pricing signal that can be routinely sent out over the internet showing the price of power during every hour of the following day. That’s the transactive energy rate.
Customers may choose to use that pricing signal to pre-determine their charging — or discharging — behavior. They may simply limit their energy usage during peak hours, thereby saving money on their bill. Or they might use bi-directional charging technology to discharge power to the grid during those peak hours and receive a bill credit for that discharge at the transactive rate, Callnan said.
While participating members will benefit from lower energy bills, the rate’s impact on moving load around should increase overall system reliability — a benefit for all 85,000 customers, Callnan said.
The co-op, which is based in Plymouth, New Hampshire, has partnered with the state university there to test the rate’s application. The results so far are promising.
Plymouth State University has two Nissan Leaf electric vehicles hooked up to vehicle-to-grid, or bi-directional, chargers on its campus. Software connected to the chargers receives price signals from the co-op every day around 4 p.m., and based on that pricing, automatically sends charging and discharging signals to the chargers for the next day.
Thus, the cars can charge in the middle of the night, when demand is low and energy is cheaper, and then discharge power from their batteries, say, around dinnertime, when demand shoots up.
Power discharged from the batteries first flows onto the university’s own electric distribution system, which helps cut its energy costs and reduces building load. Any excess goes to the grid, Callnan said.
Results after the first 30 days suggest that each car will return around $4,000 to the university annually, Callnan said.
Brian Eisenhauer, the university’s director of sustainability, said the Leaf vehicles will be used to provide a short-distance transportation service for students. The results of the pilot so far suggest that the transactive energy model “has great potential as a way to subsidize and support the electrification of a vehicle fleet. We will be exploring converting more of our vehicles.”
The charging technology was developed by Fermata Energy, which was founded by David Slutzky, an engineering professor at the University of Virginia, to help accelerate the adoption of electric vehicles and the transition to renewables.
As the country moves toward greater electrification, “electric vehicles are key to stabilizing the grid,” Slutzky said. “The Nissan Leaf became bi-directional in 2013, and there are close to a couple hundred thousand out there. Just that group of vehicles has about as much storage under the hood as the entire stationary storage industry.”
The Leaf is one of the very few electric vehicles that currently have bi-directional charging capability. It will soon be joined by a host of other electric vehicles, including Ford’s popular F-150 Lightning pickup truck.
“Everybody’s going bi-directional because they realize they have to,” Slutzky said. “The vehicles will be much more cost-effective, and they won’t be creating problems for the grid.”
As part of the transition to a transactive model, the co-op is also working with a stationary battery manufacturer that will soon offer its members batteries connected to software that can similarly read the daily pricing signal and charge and discharge the batteries accordingly. Callnan declined to name the manufacturer.
The transactive model will also make it more affordable for school districts to transition to electric school buses. The co-op is working with companies like Nuuve, which also makes vehicle-to-grid technology, on possible ways to make that happen, Callnan said.
In preparation for the new rate rollout, the co-op has updated its supervisory control and data acquisition system, known in the industry as a SCADA system, to give them greater visibility onto the distribution network, which is crucial to understanding how many additional energy resources the system can accommodate, he said.
Researchers at the Pacific Northwest National Laboratory have long been interested in the transactive energy model. A recent study based on the largest-ever simulation of a transactive grid concluded that consumers could save about 15% on their annual electric bill by partnering with utilities.
The simulation, which was modeled on the Texas power grid, also found that a transactive model would shave peak loads by 9% to 15%, and reduce daily load swings by 20% to 44%.
However, widespread adoption of smart appliances and smart load controls that automatically adjust energy usage are key to the strategy’s success, the study noted.