Two things are happening in the world as certainly as seagulls love chips: electric vehicles will replace petrol-powered cars and generation of electricity using renewable resources will replace coal. That’s good news, if you want to live in a cleaner, more efficient world.

For a long time the shift to electric vehicles, or EVs, was seen as mildly troubling by some, however, because it would lead to higher demand for power delivered in the grid. If that means an increase in supply from polluting coal plant, what’s the point? It’s a legitimate concern, when you consider predictions for additional load for EVs and that the phase out of coal could be decades away.

A neat solution, though, has whizzed into view with EVs that can feed the grid as well as be fed by it. If enough of them are plugged in to the network, the thinking goes, they could soak up clean energy at times of excess generation – predictable or otherwise – and inject some back when demand for energy is topping out.

In Canberra, the Australian National University is directing a project where 51 Nissan Leaf EVs will be connected to the grid, their batteries drawing energy for use or discharging as required for voltage control, energy arbitrage, backup power and frequency control ancillary services, or FCAS.

The trial is expected to benefit fleet owners as much as the grid. For its services to the FCAS markets each Leaf is expected to earn roughly $1,000 a year, compared with an estimated outlay for “fuel” (charging) of less than $300. “It’s significant revenue that the cars are expected to bring in,” says Bjorn Sturmberg, the research leader at ANU’s Battery Storage and Grid Integration Program. “We’ll look at it not just from an engineering perspective but to also cover that customer value proposition and business models that will be involved.”

The trial will measure benefits not only for fleet managers but also for car manufacturers, charging station controllers and energy retailers and networks. “All of those service providers are going to have to see value for it to be realised.”

Fleets account for more than half new car sales in Australia, so if the trial is a success it might fuel an acceleration in the uptake of EVs. The trial – dubbed Realising Electric Vehicle-to-Grid Services, or REVS – also involves local network ActewAGL, JET Charge, Evoenergy, SG Fleet, the ACT Government and Nissan.

Bjorn Sturmberg sees the potential for electric vehicles to stabilize the grid.

Non-financial benefits

The transition to EVs is inevitable, many believe, and university’s research will also look at the non-financial benefits or costs. “It is great for the environment and for facilitating more renewables into the electricity system but it’s also great in terms of people having backup power, being able to utilise more of their own solar, having access to revenue they wouldn’t otherwise see,” he says. “It’s a blank slate for us to work on.”

The vehicles will be used by ACT government employees, many of them health workers, and none will be taken home. It’s expected the cars will be plugged in (or “on call”) 70% of the time.

EVs have powerful potential as shock absorbers in the grid. A vision of the future electricity system is one where there is a battery in the garage, a “battery on wheels” (EV), solar on the roof, community-scale storage and utility-scale storage – all playing complementary roles in the energy system. An EV’s dual purpose, as a store of energy and form of transport, will help buyers accept they are still relatively expensive and could inspire sales. It also helps that because of its capacity the battery in an EV is already cost competitive measured against a residential battery.

Seeing EVs as a combination of a vehicle with lower cost of ownership and a residential battery “is what makes the trial exciting,” Sturmberg says.

It’s expected the cars may be called on to provide FCAS support about 10 to 20 times a year, with at most 5% of charge depleted. That shouldn’t be enough to trigger concerns about an invisible party having access to your store of energy, but humans are not rational creatures. “Technically you can convince yourself on an engineering front that these problems are small and can be addressed but there’s a big gap between that and having something people who buy electric vehicles can understand and are comfortable with,” Sturmberg says.

The transition to EVs presents a prime opportunity to solve the problem of surplus solar output, but only if enough cars are plugged in to the grid around noon. This is the purpose behind Western Power’s 100MW Industry Challenge in Western Australia, where 100MW of flexible load is sought to match 100MW of solar added to the grid each year.

“Without vehicle-to-grid, electric vehicles are about as useful to the grid as a car with a steering wheel that only turns left,” Sturmberg says. “Occasionally it still gets you to where you want to be but a car with a wheel that turns both ways is superior and that’s what vehicle-to-grid allows.”

The REVS trial could show the way to design more dynamic virtual power plant models, says Tim Washington.

It ain’t easy

The trial will test more than the usefulness of EVs as grid assets, says JET Charge founder Tim Washington. For example, the relatively small capacity of a home battery means there isn’t much room to participate in virtual power plants, or VPPs. “[Homes that take part in VPPs] only provide a little bit of support because most of the electricity is used to power the house,” Washington says. The more EVs there are plugged into the grid the more their batteries will be able to accommodate virtual power plants and encourage large-scale renewables to connect.

The EVs in the REVS trial will discharge automatically when they detect a drop in frequency, Washington says, but that doesn’t mean the project is a simple set up. The compliance and metering requirements are complex, and there are a lot of unknowns about performance of a bidirectional charger. “JET Charge’s role is to make sure the charging stations work under FCAS regulations,” Washington says. “It sounds easy but it’s not.” Stationary storage can send out electricity pretty simply but when it’s a car you have to think about a whole lot of other things.

Washington expects the trial will highlight how better use can be made of rooftop solar. “Not everyone can afford to get a battery storage unit for self-consumption purposes but people do tend to buy cars. As prices of EVs come down people will buy them as vehicles first but then they have the co-benefit of being used as energy storage.”

Australia has about 1.8 cars per household, with the second vehicle parked 95% of the time – a perfect opportunity for it to be used as storage for rooftop PV. The batteries in these cars – many times larger than typical home batteries – could allow for much larger residential PV systems.

The bidirectional chargers in the trial will be installed later this year and ANU will prepare engineering, social and commercial studies to understand what vehicle-to-grid networks can offer to consumers and the grid.