Electric car owners will be called on to help Britain avoid an energy crunch as suppliers prepare tariffs allowing them to draw power from parked vehicles at times of low supply or high demand.
Cars which are charging on driveways are to be plugged into a system responsible for balancing the National Grid for the first time, in an experiment aimed at easing the burden on the country’s creaking energy infrastructure.
It will lay the groundwork for a national rollout of the technology if successful, paving the way for millions of electric cars to act as a giant battery so that power supply is stable at times of low wind speeds after the transition to green energy.
In the trial, which will begin at some point from April to June, car owners will agree to allow the grid to draw power from their vehicles and release it as and when required. They will be paid for energy which the grid drains off.
The scheme is being run by the National Grid and domestic supplier Octopus Energy, which has recruited 135 households.
Claire Miller, director of technology and innovation at Octopus, said that plugging millions of electric cars into the grid would “enable us to do more with what we have”.
Ms Miller said: “This will demonstrate how you can send a signal from the National Grid control room to those vehicles and contribute to balancing the grid at times when it needs a bit more electricity, for instance at tea time when there is a lot of demand.
“Conversely, on a windy night when our wind turbines are generating electricity, we might also need a place to put energy.
“What we’re doing is the first step on that journey. We are showing the energy industry what is possible.”
The plans go considerably further than existing trials of so-called vehicle-to-grid technology, in which a small number of households already sell surplus power from their vehicles’ batteries back to the grid in the same way solar panel owners do but are not part of the balancing mechanism.
Julian Leslie, chief engineer at the network operator National Grid ESO, said they were working to ensure the network was fit for “a heavily renewables-driven” future.
He said the grid would always find ways to manage but added: “If we can get 10 million vehicles doing vehicle-to-grid, then fantastic.”
The balancing mechanism is what the National Grid ESO uses to make sure electricity supply matches demand and the lights stay on.
Grid operators have to monitor the system second-by-second, trading and storing power to smooth out any imbalances.
This task is becoming harder as the country moves away from burning “dirty” fossil fuels towards using cleaner but more unpredictable energy sources such as wind and solar.
The UK is planning to quadruple offshore wind power production by 2030.
As part of its work with Octopus, the National Grid ESO’s control room has been testing how to send and receive signals from cars that are part of the vehicle-to-grid trial.
Eventually it is hoped these cars could be called upon to release charge when extra supply is needed, or in turn create demand by drawing power.
Ms Miller said that a typical electric car had an output of about seven kilowatt hours.
At peak hours, or between 4pm and 7pm, a typical household would only use around three kilowatt hours of energy, leaving about four kilowatt hours of spare capacity.
That means one million electric cars could provide 4,000 megawatt hours to the grid at peak times – roughly the same as 5,000 onshore wind turbines, Ms Miller said.
To incentivise car owners to plug in, participants in the Octopus trial are being paid a generous sum of 15p per kilowatt hour for the electricity they send to the grid, or 60p per hour.
Ms Miller added that “smart charging”, when automatic systems charge electric cars at times when demand for power is lowest, will significantly reduce pressure on the energy network as well.