The U.S. National Renewable Energy Laboratory (NREL) is testing a novel technology that could prevent electric-vehicle charging from crashing the grid.
The technology, from Californian startup PowerFlex Systems, is aimed at building owners looking to provide EV charging points, for example in parking lots.
Not only does it make sure simultaneous EV charging does not overstress the grid, but it also prevents building owners from incurring peak demand charges.
“PowerFlex's technology reduces peak demand needed to run electric-vehicle stations by 50 percent, by incorporating driver inputs and real-time load monitoring,” said Trish Cozart, NREL manager for the Wells Fargo Innovation Incubator program, which is funding the firm.
The company achieves this cut in peak demand power in two stages. The first looks at how many vehicles are connected to charging points, and how long they are able to charge for.
When drivers hook up their cars to a PowerFlex charger, they use a mobile app to tell the system which charging point they are using, what kind of vehicle they have, when they need to pick it up and how far they will be traveling afterward.
This information allows the system to work out how much power to send to each vehicle, and when, while keeping the overall energy draw within a reasonable limit.
Such load management techniques are already being investigated elsewhere and can help ensure that simultaneous wide-scale EV charging does not bring the grid down.
But they could still land building owners in trouble, because if a charging station is creating a significant load on the electrical system then the owner could end up paying demand charges if other facility loads, such as heating or air conditioning, push consumption up too high.
The PowerFlex system gets around this with its second stage of operation.
Here, it plugs into the building electrical system and monitors the flow of power to major loads such as lighting, heating, ventilation and air conditioning, as well as the potential output from solar panels, batteries and other distributed energy technologies.
PowerFlex’s system uses this information to determine when it can reroute extra power to the vehicle-charging station and when to cut back on the station’s energy. Besides avoiding demand charges, the system could potentially help building owners accommodate extra charging points without having to pay for electrical upgrades.
According to a PowerFlex presentation from July last year, the conduits and wiring needed to accommodate electric vehicles cost about $3,000 per parking space for fewer than 10 spaces.
But above this number of vehicles, the cost rises to $7,000 per space due to the need for transformers and distribution panels. Beyond 30 vehicles, the cost is $10,000 per space because of the need to install new feeders and switch boards.
The PowerFlex system, which is “at a commercially ready stage,” said Cozart, has been deployed at locations including the NASA Jet Propulsion Laboratory, the Los Altos School District in California and NREL’s National Wind Technology Center in Colorado.
The NWTC installation covers 16 EV charging stations. PowerFlex “is seeking assistance testing joint optimization of EV charging and grid operation, for which NREL will provide expertise,” said Cozart.
NREL has also given PowerFlex $250,000 in funding through the incubator program. Companies that have participated have gone on to raise more than $89 million in follow-on funding, Cozart said. They include ESS Inc., a flow battery maker that last December raised $13 million from investors including BASF, the global chemicals giant, and Growing Energy Labs Inc., which in April pulled in $5.5 million after previously being backed by Shell Technology Ventures.
Of 20 firms that have participated in the incubation program so far, four have been subject to mergers and acquisitions, Cozart said.
Analyst Timotej Gavrilovic, lead author of the EV Charging Infrastructure Development and EV Charging Infrastructure Landscape reports from Wood Mackenzie Power and Renewables, said the charging optimization software being developed by PowerFlex is interesting. “Overall, I think they are definitely worth keeping an eye on,” he said.
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