Mike Scott reports on how vehicle to grid, a technology where the UK has global leadership, is set to help overcome the challenges of mass EV roll-out and ever-larger quantities of renewables on grids
While sales of electric vehicles (EVs) are likely to be depressed this year by the Covid-19 pandemic, in the long run the automotive market will become increasingly electric. And as technology advances, batteries will become more powerful and able to charge faster.
This will create new demands on electricity networks, at the same time as these networks become increasingly dominated by renewable energy, particularly the intermittent sources of wind and solar PV, which require more intervention to balance the grid.
The Covid-19 pandemic has given valuable insights into what might happen, says Chris Wright, chief technology officer at smart battery software company Moixa. “Because the overall load has fallen due to reduced economic activity, the share of renewables on the system has increased. There have been many occasions recently when the share of renewables was above 50%, which was said to be impossible until quite recently.”
In future, we will need far greater system-balancing flexibility to manage the grid
As well as the need for frequency regulation to deal with the second-by-second fluctuations in power from wind and solar facilities, the increasing proportion of renewables also creates supply that does not always coincide with peak demand: many wind farms generate more power at night than during the day, while the supply of solar power is plentiful during the day but tails off just as demand peaks in the evening.
The easiest way to deal with these mismatches is to store surplus energy – mostly in batteries – when it is generated, and release it for use later when it is needed.
But as the number of EVs on the roads grows rapidly in coming years, the stresses on electricity networks will continue to increase. “In future, we will need far greater system-balancing flexibility to manage the grid,” says John Murray, head of EVs at energy consultancy Delta-EE.
While this is partly because of the need to charge EVs, at the same time, the “majority of the storage that gets deployed in the next 10 years will have wheels on it,” Wright says. In other words, EVs can be part of the solution to the challenges they are creating, through vehicle-to-grid (V2G) technology. This allows cars to feed power back into the grid via a bi-directional charger.
One EV can provide three to four days electricity for a family home, says Tepco, the Japanese electricity utility that invented bi-directional charging technology, while Wright of Moixa adds that 10 Nissan Leafs “have enough energy in them to power 1,000 homes for an hour”. That makes V2G a powerful weapon in the battle to balance grids and provide frequency-regulation services.
However, Murray says V2G is unlikely to make much of an impression in the near term. “In the next five years, individual smart charging will be more common,” he says.
The value you will be able to generate from V2G is 10 times more than from smart charging
Smart charging allows EV owners to charge their cars when demand is lowest, normally overnight, often in conjunction with a lower tariff. As the number of EVs in circulation increases, overnight charging will provide demand for clean energy generated when there are few other customers and reduce pressures on the system during peak times. At the same time, it makes charging cheaper.
A number of power companies are starting to offer packages that enable smart charging, including Ovo and Octopus Energy. Claire Miller, director of technology and innovation at Octopus Electric Vehicles, says one of the company's tariffs "is aimed specifically at EV owners who can charge their cars overnight, and offers power at 5p/kWh between 12.30am and 4.30am, compared with 14p/kWh at other times. Agile Octopus provides half-hourly pricing that allows customers to take advantage of cheaper wholesale energy prices. If you can shift your energy consumption outside the 4-7pm peak, you can make significant savings, and when there is too much supply on the grid, the tariff goes negative. These tariffs are a way to straddle the energy transition and the mobility transition,” Miller says.
However, Francisco Carranza Sierra, managing director of Nissan Energy, which is developing V2G options, points out that the benefits of smart charging end once the battery is fully charged. “And you only benefit at low prices,"he says. "The value you will be able to generate from V2G, because you can sell power at high prices, is 10 times more than from smart charging.”
In addition, smart charging on its own will not be enough to balance the grid once EVs are commonplace, says Moixa's Wright.
But V2G remains some way off, in part because the chargers are still too expensive – around £5,000. This is down from £10,000 in the past couple of years, but much more than the £1,500 cost of a smart charger. On top of that, until recently, the chargers used to be the size of a fridge and weigh about 300kg, says Carranza Sierra.
There are also currently restrictions at a hyper-local level because some distribution grids cannot cope with the input of extra power. “What’s already on the grid, what you’re doing as a property, the houses around you, [all] affect what you can do,” says Miller. “Network operators need to know where the weaknesses are, so they know where to invest in upgrading.”
Distribution companies also need to know precisely where power is going to be injected into the grid, so consumers need to get permission to install bi-directional chargers, a process that takes about three months, adds Carranza Sierra.
We will not be able to put 100% of the EVs we make on the road because charging them will shut down the grid
Nonetheless, chargers are now about the size of a large shoe box and the weight is down to about 40kg, says the Nissan Energy chief, who says V2G is almost ready to hit the market, not least because without it “we will not be able to put 100% of the EVs we make on the road because charging them will shut down the grid”.
The technology is hugely versatile – indeed, Japan's electricity utility Tepco calls it V2X, or vehicle-to-everything. The possibilities include V2V (using EVs to charge other cars), V2L (vehicle-to-load, which can be used for everything from campsites to construction sites) and V2H (vehicle-to-home). These capabilities have been particularly important in Japan since the 2010 earthquake, when EVs were sent to the Fukushima region to provide power to allow residents to heat their homes and to charge computers and mobile phones after the tsunami, says Naotaka Shibata of the Tepco Research Institute.
Given its vulnerability to earthquakes and typhoons, this disaster-recovery role is important in Japan, where about 5% of EV owners have V2H capability.
Yet the global leader in V2G development is the UK, Shibata says, thanks to a £30m fund set up by Innovate UK. “There are more than 40 V2X demonstration projects around the world, and 21 of them are in the UK,” he adds.
One of these is a joint venture V2G pilot project between Moixa and Honda, in the London Borough of Islington. “We put V2G units in five electric vans based at Islington Town Hall. That is enough to take the baseload of the building, and the vans can charge when power is cheapest and greenest.”
The first V2G projects are likely to involve companies that have commercial fleets, which provide the scale to make the process worthwhile and use patterns predictable enough to be useful to grid operators. Nissan has teamed up with EDF to provide V2G-compatible vehicles, chargers, and the ability to offer grid services to businesses in the UK, France, Belgium and Italy.
Cycling the battery while the car is stationary has no negative impact and is a very stable way of removing electrons
Individual drivers are likely to be more reluctant to allow their cars to be used like this, in part because of the loss of flexibility and also because of concerns about battery deterioration from repeated discharges. An increase in leasing rather than owning cars outright may ease such fears, Miller says. “There is emerging research that cycling the battery while the car is stationary has no negative impact and may actually help because it’s a very stable and controlled way of removing electrons from the battery. But if you’re leasing, even if it does have an impact, it’s not your problem.”
There is still a long way to go before V2G becomes mainstream: there need to be more EVs on the roads and on the grid, more knowledge about use cases and the grid’s needs in relation to EV charging at both national and local level, and the costs must come down significantly. But once there are 10,000 EVs connected to the grid, V2G can start to play a role nationally in balancing it, Carranza Sierra says.
Dr Marco Landi, innovation lead for V2G and EV charging at Innovate UK, says V2G is not going to make EV owners millions of pounds and solve all the problems of the grid. But it “can turn EVs into ‘flexibility’ resources, generating value for customers, making the power system more reliable and increasing penetration of renewables. And it could save the system £3.5bn a year. The IEA and the National Grid both assume that V2G will play an integral part in our future energy system.”
Mike Scott is a former Financial Times journalist who is now a freelance writer specialising in business and sustainability. He has written for The Guardian, the Daily Telegraph, The Times, Forbes, Fortune and Bloomberg.
This article is part of our in-depth Energy Transition briefing. See also: