Until recently, Gary Hogben did not expect he would ever be paid to simply plug his car into the wall every night.
And yet, over the past year, that's exactly what's happened. He and his wife have earned more than $1,000 while their car sits in the driveway.
The service is called V2G, or "vehicle to grid", and it could be an important component of Australia's electricity grid in coming years, plus a way for car owners to make a little extra income.
Gary Hogben gets paid to export energy from his electric car's battery to the grid.(Supplied: Gary Hogben)
The concept is fairly straightforward: electric vehicles (EVs) are essentially very large batteries on wheels. Most of the time they sit idle.
With V2G, the batteries in parked EVs are hooked up to a special "bi-directional charger" and coordinated through a central server to export power to the grid during periods of high demand (namely, the evenings, when people turn on appliances).
EV owners like Gary are paid for each unit of energy they export. They then recharge their EV batteries overnight, when demand is lower and energy is cheaper.
Under his current tariff, Gary gets about 30 per cent more for each unit of energy he exports than for the unit he imports.
He and his wife trialled V2G to reduce the household's carbon footprint, but now he's making bank.
An app screenshot showing the monthly summary for V2G services in June.(Supplied: Gary Hogben)
"We're exporting between 5:00pm and 9:00pm and importing generally after about 10:30pm," Gary said.
"We didn't do V2G because of the financial incentive at all, but financially it's worked out very well indeed."
Up to four times the capacity of a standard house battery
But there's a catch. Actually, there are a few.
The first one is that Gary doesn't live in Australia. He's in Liverpool in the UK — which is ahead of Australia on this technology.
As fossil fuels are replaced by renewable energy sources, there's a great need for new ways of storing and rapidly distributing energy.
Energy generated by solar and wind when the sun is shining and the wind is blowing has to be stored so it can be dispatched to the grid during periods of higher demand (namely, the evening, when people use appliances).
Big utility-scale batteries like the300MW whopper being installed in Victoriaare one solution.
A complementary solution is V2G.
A diagram showing how V2G works for the REVS trial.(Supplied: REVS)
In July last year,one of the first Australian V2G trials began in the ACT, led by the Australian National University (ANU).
The two-year Realising Electric Vehicles-to-grid Services (REVS) trial would test V2G on a fleet of 51 mostly ACT Government EVs.
But it quickly hit a roadblock: bi-directional chargers (that can charge EV batteries and also export power from these batteries to the grid) had not been certified for use in Australia.
That's now been resolved and the newly certified chargers are on their way.
"I see the trial operating by the end of the year," said Geoffrey Rutledge, ACT government lead on emissions reduction.
Mr Rutledge believes V2G can help stabilise the grid, while also giving EV owners a new use for the big new batteries they bought with their car.
"An EV battery is three to four times the size of a standard battery seen on the side of a house," he said.
Canberrans generally travel 35 to 40 kilometres a day, he added, meaning batteries (typically with a range of more than 500km) parked in driveways will have plenty of juice left over for the grid.
And the V2G financial dividend could drive EV sales, he hopes.
"EVs will be as cheaper or cheaper than the current alternative," he said.
By 2025, all new EVs will be V2G capable
If all of Australia's 19 million cars were EVs, they would hold a truly staggering amount of energy.
Bjorn Sturmberg, research leader at ANU's Battery Storage and Grid Integration Program, which is leading the REVS trial, calculates it would be equivalent to more than 10,000 Tesla Big Batteries.
The100MW Tesla Big Battery in South Australiawas the world's largest lithium-ion battery when installed in 2017.
The Hornsdale Power Reserve, otherwise known as South Australia's Tesla battery powerpack.(ABC News)
"One EV battery typically contains as much energy as an average household uses over two-to-four days," Dr Sturmberg said.
"On top of this, it can react to events in a tenth of a second.
He said Australia was well placed to take advantage of V2G, due to it being a world leader in rooftop solar.
"Because of that, we have quite a lot of industry engagement from the electricity sector," he said.
But there's a long way to go.
The battery technology used in most EVs today, called CCS, is not compatible with V2G.
Of the cars sold in Australia, only the Nissan Leaf ZE1 and Mistubishi Outlander plug-in have V2G charging capability.
But that's due to change. By 2025, all new EVs will be V2G capable.
A Nissan Leaf at an EV charging station in Poland.(Getty: Michal Fludra)
On top of this, there are so few EVs in Australia (and continued low sales) that it'll be a long time before V2G is much help to the grid.
But the Australian Renewable Energy Agency (ARENA) still sees "enormous potential" in V2G, says its chief executive officer Darren Miller.
The agency is providing more than $7.5 million in funding for four projects looking into V2G and smart charging (charging EVs during off-peak hours), including the REVs trial.
"We have heard people talk about EVs as "batteries on wheels", and when you project forward the inevitable uptake of EVs in the years ahead, you can appreciate the huge energy storage potential that will exist in the EV fleet," Mr Miller said.
"It is really only just starting to kick off around the world, as no country has adopted the technology at scale yet.
"We expect to see a few more years of trials and a bigger range of V2G-enabled car models with a larger consumer uptake before things truly take off."
'V2G doesn't always make sense to people'
But will consumers want to hand over control of their battery?
Kat Lucas-Healey, a researcher at ANU, recently interviewed more than 30 EV owners from around Australia on this topic.
She found that many appeared reluctant. Fleet managers were working to reduce their organisation's emissions, while householders were generally trying to reduce their home's carbon footprint.
Helping stabilising the energy grid (as important as that is) wasn't a huge motivator.
The V2G bi-directional charger at Gary's home.(Supplied: Gary Hogben)
On top of this, V2G can be hard to understand and a little counter-intuitive (getting paid to plug your car into the wall!).
Whereas popping a solar panel on the roof to make power and use less energy from the grid is pretty straightforward and easy to understand, V2G is more complex, Dr Lucas-Healey said.
"You're giving a third-party permission to do things with your battery. It's a complex piece of kit interacting with a complex system, which is the grid."
A Facebook page for EV owners taking part in V2G trials in the UK is full of complaints about technological glitches and punitive tariffs.
Several participants said they would switch to vehicle-to-home charging (V2H) upon completing the trial. The main reason they took part in the trial was to collect a free bi-directional charger.
With V2H, the EV serves as a giant battery to power the home with cheaper electricity imported during off-peak hours (reducing electricity costs and also providing back-up in the event of a blackout).
It's like V2G, but disconnected from the grid.
The ACT government's Geoffrey Rutledge also noted there was "mixed consumer feedback" from the UK's V2G trials.
ARENA's Darren Miller had similar concerns.
"There is also the as yet unanswered question of whether EV owners are willing to allow their vehicles to be used to power their homes or provide energy to the grid, and also whether vehicle manufacturers will warrant the batteries to be used in this way," he said.
'They can say to their friends, I can power my house right off my car'
That leaves one final obstacle: the expense of the bi-directional chargers.
A Melbourne-based company, JET Charge, will be selling the first of these in Australia later this year for about $10,000.
That's about 10 times the cost of a standard one-way home EV charger.
But JET Charge CEO Tim Washington said he was confident there would be buyers.
Some standard one-way EV chargers in Adelaide CBD. Could bi-directional chargers become the norm?(ABC Radio Adelaide: Malcolm Sutton)
He said there were a "dozen" corporates interested in trialling the technology and a waitlist of "hundreds" of residential retail buyers.
"People are motivated by energy freedom," he said.
"Then there's environmental factors. And people also buy because it's cool.
"It's bragging rights. It's early adopter syndrome."
For some, it may even make economic sense. A Tesla Powerwall, which has a smaller capacity than most EV batteries, costs more than a bi-directional charger.
Mr Washington speculated that users could even charge their car for free at work to power their home in the evenings.
"Employers have the means to provide cheap EV charging, with large car parks and large roof space covered in solar," he said.
"You could drive to work, plug in, get a whole battery, and then go home and power the house for two days."
