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Green Wheels: EV-powered homes could reduce electricity demand

There are two versions of the technology. One lets electricity flow from an EV to the grid, the other supplies electricity directly to the home.

Published July 20, 2012

This summer, storms took electricity from millions of Americans, leaving them sweltering and with food rotting.

Much of Japan went black after last year’s tsunami.

It could happen here, especially since climate change is forecast to unleash increasingly violent weather.

That’s one reason for growing interest in technology that lets power flow from plugged-in electric vehicles as well as into them.

Another is that as more electricity is generated by wind and solar, which produce only intermittently, we’ll need additional means to stabilize the grid between immediate supply and demand.

Two-way power could also smooth the typical daytime peaks and overnight troughs in demand.

The notion of using EVs for these chores has been around for two decades, but it’s complex and technology is just catching up to concept.

Not surprisingly, Nissan is among the leaders. Although the company’s battery-powered Leaf gets rave reviews, sales are well below expectations. Why not try to enhance its appeal?

There are two versions of the technology. One lets electricity flow from an EV to the grid. It’s called, of course, vehicle-to-grid, or V2G. The other allows the car to directly supply a home. Surprise: It’s known as vehicle-to-home, or V2H.

While the names are simple, making it work isn’t, particularly for V2G. The EV battery and controls must meet strict requirements for fast, seamless communication with the grid and ramping up and down electricity flows in both directions.

Hydro-Québec’s research arm, IREQ, which is developing a unique lithium-ion battery, just began tests of grid and home systems with Quebec-based B3CG Interconnect.

Nissan, focusing on V2H, recently announced progress with companies that make charging stations in Japan and the United States. Last month, it presented a demonstration of its own proprietary technology at Georgian College, in Barrie.

It says the Leaf’s 24-kilowatt-hour battery pack could run a typical Canadian home for about a day; in Japan, for two. Those times could be stretched if, for example, the car must only power a fridge or freezer during an emergency.

As a bonus, the device recharges the Leaf’s battery in just four hours — one-third the time in the car’s current set-up and two hours better than the 2013 model.

The unit’s cost hasn’t been set here — and there’s no schedule for it to be commercially available — but in Japan it’s equivalent to nearly $3,800.

As always, there are questions.

Obviously, using a car as a power supply is possible only if it’s parked and the system keeps enough juice in the battery for when it’s needed. Since the average North American car is on the road just over an hour a day that seems fine — except that idle vehicles might be far from the home driveway.

A U.S. study designed a model for EVs in an office building’s parking garage. Drivers would be paid for power they supply and pay for any recharging. One conclusion: It might be better to supplement the grid using stationary lithium batteries.

The price of V2H seems high — about double the cost of the 240-volt charging stations recommended for EVs. To balance that, in places like Ontario with peak and off-peak periods, a battery could be filled at low overnight rates and replace higher-cost electrons during the day.

On the other hand, batteries last a limited number of charging cycles: Additional use would shorten their life and, since they’re worth upwards of $10,000, that’s a big deal.

As for V2G, it won’t make sense until enough EVs are in service, with significant numbers in given areas, to stabilize the grid. A report by Pike Research says V2G could be cheaper than building generating stations, and forecasts that by 2017, 91,500 electric cars and trucks will be linked to it, pulling in $18 million.

Small potatoes, sure. But much money is going into these schemes, as well as charging networks and other EV services. And the more committed, the more pressure to keep going.

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