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Boulder’s tests bi-directional charging

 by Allen Best

Can electric cars keep the lights on at home or the office — or the recreation center?

Boulder has set out to learn the answer. This may be a first in Colorado. It has installed a new vehicle-to-building charger at the North Boulder Recreation Center. The bidirectional charger from Fermata Energy works both ways. It can deliver electricity from the building to the car, or electricity from the car to the building.

Why would this matter? Because of peak demand charges. The city government’s rates are based on peak use. That typically occurs from 2 p.m. to 6 p.m., but especially on hot summer afternoons, electricity use can rise.

Xcel Energy, the utility serving Boulder, charges substantially more when it has high demand on its system. If Boulder can shave the peak off this mountain, it might be able to save money.

For this experiment, Boulder is using a Nissan Leaf from its fleet of 21 electric vehicles. The car’s battery has 62 kilowatt-hours of storage. That’s enough electricity to meet the average demand by a Boulder home for four days. The average home in Boulder uses 478 kilowatt-hours per month.

A recreation center uses a lot more electricity than that, of course. The idea is to shave off the peak.

Matthew Lehrman, the city’s energy strategy advisor says that the bidirectional charging infrastructure could be expanded to include 2, 5 or even 10 electrical vehicles. He expects results from the study to be ready to share in early 2021. It will be posted at the city’s Department of Climate Initiatives website.

What about when somebody needs the car? “The pilot is designed to allow the fleet driver to use the car any time it is needed. So, a charge or discharge cycle can be stopped at any time,” Lehrman explains. “This would, of course, prevent demand management at that time but the hypothesis is that the vehicle is parked enough of the time to reduce peak demand.

It’s unlikely this is the first time somebody has done this experiment. Certainly, innovative utilities in Colorado and elsewhere have been thinking about the possibilities. This trial in Boulder is an opportunity for the city to see how the technology works.

“This has been on our radar for a long time,” says Lehrman. “The cars are just sitting there. The city is always looking to try new technologies. We were early adopters of the modified EVS in 2008 and 2009.”

Lehrman says if this experiment pans out, the use of bidirectional charging could be expanded to more electric cars to create what is called a microgrid at an office park or even in a residential neighborhood. Most microgrids, such as the experiments conducted by Xcel Energy at the Denver neighborhood formerly known as Stapleton (now Central Park), have used batteries in homes.

This is from Big Pivots, which chronicles the great energy transition in Colorado and beyond. Sign up at

In trying to create its own municipal utility, Boulder had wanted to push the envelope of new technology in ways to reinvent the grid and wring the carbon out of its electrical supply. In November, city voters chose instead to accept a new franchise with Xcel. That agreement calls for Xcel and Boulder to cooperate on innovations.

“Proving this technology is exactly the sort of thing that could be useful for the broader partnership,” says Lehrman.

Fermata Energy, the company that installed the bi-directional charging system, conducted a demonstration project in 2019 that resulted in the new technology being the first in the world to be certified to a new North American Safety Standard.

This year, E Source —a leading research and advisory firm for the energy sector – conducted a case study that concluded that Fermata’s V2G technology discharged less than half of the battery capacity of a Nissan Leaf for a peak 15-minute period and saved $191.79 in utility bills during a month in Danville, Va.

Allen Best
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