Snohomish County Public Utility District in Washington State has contracted with Mitsubishi Electric, Hitachi ABB and Doosan GridTech to install two electric vehicle-to-grid (V2G) chargers.
The V2G chargers are being sited at Snohomish PUD’s Arlington microgrid site and will be able to charge an electric vehicle and also send the stored energy back to the grid during a power outage.
Snohomish PUD began planning its Arlington microgrid project four years ago. It is now nearing completion, which is expected in January 2021. The $9 million project, which includes a $3.5 million grant from the Washington Department of Commerce, includes a 500-kilowatt (kW) solar array and a 1-megawatt (MW), 1.4-megawatt hour (MWh) battery system, as well as the two Mitsubishi two-way capable electric vehicle chargers.
Doosan’s DERO distributed energy resource management system (DERMS) will control the Arlington microgrid’s energy storage system, as well as the electric vehicle charging stations when grid connected. Doosan is also partnering with Awesense, a Canadian software company that is integrating its digital energy platform with Doosan’s DERMS to gather more granular data on the distributed energy resources, V2G devices and other assets involved in the project to provide accurate, real-time data and analytics.
The microgrid is designed to support a new local office that Snohomish PUD is building in Arlington, north of the utility’s Everett headquarters, to accommodate growth in the northern part of the county.
The microgrid will allow Snohomish PUD’s Arlington operations center to continue to operate in the case of an outage. But the microgrid will also be able to provide revenues when the system is connected to the grid in the form of ancillary services such as peak shaving, energy arbitrage, and capacity firming.
For instance, the solar-plus-storage microgrid will be able to offset charges Snohomish PUD would have to pay its wholesale power provider, Bonneville Power Administration, to provide capacity firming, also known as solar smoothing, during times when solar output drops because of conditions such as cloud cover.
In that way, the microgrid is “earning its keep,” Scott Gibson, project manager for the Arlington microgrid, said. “It is benefitting the grid daily. It is a solar powered emergency generator with a day job.”
Snohomish PUD plans to use the two-way capable electric vehicle chargers to power up utility electric vehicles. Snohomish PUD is just starting to build up its electric vehicle fleet, Gibson said.
Currently, the utility has four electric vehicles, two Nissan LEAFs and two Kia Niros. The LEAFs will be used for the V2G system.
While V2G technology has often been touted as a promising form of mobile storage for the grid, achieving that promise is more difficult. “There is a big controversy with V2G, about whether to use public vehicles or fleet vehicles,” Gibson said. “In our opinion, it is tough to find the right incentive to allow owners to let us use their vehicle.” An electric vehicle that is also feeding the grid would be charging and discharging more frequently than a vehicle that is only being used for transportation and that degrades the battery more rapidly. “Everybody is struggling with that,” Gibson said.
A utility, on the other hand, can monetize the discharge functions of an electric vehicle for the benefit of the grid. Gibson noted that if a utility were to have 16, 60-kWh Nissan LEAF electric vehicles, it would essentially have 1 MWh of storage.
“We see this as an important step in our 'utility of the future' vision and for SnoPUD to be one of the premier utilities in the country,” John Haarlow, the utility’s CEO and general manager, said in a statement.
While the Arlington microgrid is a pilot project, it is “an actual functioning system,” Gibson noted. There are a lot of similar demonstration projects but “this will be one of the first to truly put a functioning grid connected V2G system together,” he said.
Among the challenges that come with building a pioneering project is integrating the various pieces of the system. “Electrically the system is pretty simple,” Gibson said, but getting the different controllers to talk to each other is a challenge.
The Mitsubishi V2G chargers have their own control system, which must talk to the microgrid control system, a task made more difficult because control of the microgrid depends on how it is being used.
When the microgrid is connected to the grid, it will be controlled by Doosan’s DERMS system. When the microgrid separates from the grid during an outage and is in islanded mode, it will be controlled by the Hitachi-ABB microgrid control system. “It is really a unique system,” Gibson said.
In the initial stages, Snohomish PUD’s recovery of its investment in the microgrid project will be learning, Gibson said. “When the energy market changes, though, there will be more value and we will be able to step right in and take advantage of that.”
“We have an incredibly supportive commission and general manager, who all see this as part of our future” Gibson said. With that vision, “the more we invest, the more we can take advantage of it.”