Sceptics say EVs will overwhelm the grid. In fact, they could be part of the solution

Electric cars make some people afraid of the dark. While the batteries produce much less carbon, they require much more electricity to run. This has prompted ominous warnings that Great Britain and other wealthy countries set on banning new petrol and diesel cars risk plunging their populations into darkness.

In recent months British net zero-sceptical newspapers have warned that the shift to EVs would “risk overwhelming the grid, and threaten catastrophic blackouts” when intermittent sun and wind fail to provide the necessary power. Another article claimed: “It won’t take an enemy power to put us all in the dark – just energy customers doing normal things on a normal winter’s evening.”

Yet many of the people working in the electric car industry think these fears may be misplaced. They argue that the shift to electric cars offers an exciting – and potentially lucrative – chance to build an energy system that is smarter, as well as greener.

Related: Worried carmakers call for urgent UK help to reignite waning interest in electric vehicles

Polluting coal-fired power stations have been replaced in the UK mainly by windfarms and solar panels. Those renewables produce zero carbon emissions, but they have an intermittency problem , failing to provide much power on still, cloudy days and nights. Add in the prospect of every new car shifting to electricity by 2035 , and it is not outlandish to ask how the grid will maintain the balance between supply and demand.

Demand shifting

The shift to electric cars will certainly require much more electricity generation, as it becomes the main source of energy for transport, rather than fossil fuels from the ground. However, smart technology can be used to shift demand away from peak times, such as 5pm on a winter’s day, when electricity demand threatens to outstrip supply.

This is not just a pipe dream. The home charger company myenergi calculates that if balancing services were enabled on every one of its compatible installed chargers “we could offer the grid more than 1GW of demand shift flexibility – larger than 98% of the UK’s major fossil fuel generators”.

Octopus Energy, which has grown rapidly to become the UK’s largest energy supplier , says that its Go electric tariff manages the charging for 150,000 electric car batteries. They would require 1GW of power to charge at the same time, but smart chargers hold back until the quiet hours of the night, shifting that demand away from the peak. Electricity is also cheaper at quiet times, providing a clear consumer benefit. Octopus says their customers save about £600 a year on average.

A gigawatt is equivalent to a mid-sized power station – enough to power 600,000 homes. The electric cars on Britain’s roads could already make a dent in the UK’s peak winter demand for electricity of 61.1GW , according to National Grid, simply by delaying charging by a few hours.

Jack Fielder, myenergi’s chief strategy officer, says: “If every EV charger could deliver grid balancing services, and every driver opted into grid balancing programmes, we could collectively eliminate periods of pressure for the grid.”

It could also help when electricity supply outstrips demand, such as during a warm, windy night, says Chris Pateman-Jones, chief executive of Connected Kerb, a charging company.

“Instead of diverting renewable power into the ground, my view is that EVs could act as a massive sponge,” he says. There would be little change to users. Most cars have finished charging by midnight, according to Connected Kerb’s data, leaving hours of idle time before the car is needed.

Powering the grid with car batteries

It is not just about the timing of when electrons flow into car batteries that could be of use to the National Grid Electricity Supply Operator (NGESO), the company tasked with balancing Great Britain’s grid. It calls demand shifting a “low-regret action to help reduce the impact on peak demand and reduce curtailment of renewables”, but it also wants electrons to move the other way.

Vehicle-to-grid technology is a tantalising prospect. Rather than building power stations, hydroelectric storage or banks of stationary batteries, the idea goes, we can use the energy stored in car batteries. The car becomes a portable power pack, a backup for power cuts in the home, and even allows drivers to make money by selling power back to the grid.

The NGESO produces annual guesses of what Great Britain’s electricity system will look like in 2035 and 2050. It sees a big role for cars feeding power back into the grid. Capacity could reach 39GW in its most optimistic scenario (equivalent to a tenth of massively expanded electricity generation capacity).

Figures from Pod Point, another home charger company, suggest that most cars are only drawing power about a third of the time they are plugged in. That means there is ample flexibility to sell small amounts to the grid at expensive times, before buying power back overnight when things are cheaper.

However, James McKemey, Pod Point’s head of external affairs, cautions that bidirectional charging is further off than much simpler demand shifting.

“Getting 5kW [of power] out of a car is a lot more difficult than saying to five different cars to take 1kW less,” he said. For now the extra costs – particularly of the inverters needed to switch from direct current from batteries to alternating current on grids – have stopped many carmakers from including them on cars as they race to cut prices.

Nevertheless, carmakers are starting to install the technology required for bidirectional charging. Models from BYD, Hyundai, Renault, Nissan and SAIC’s MG are capable of bidirectional charging, and more are likely to follow. Shan Tomouk, a charging analyst at the consultancy Rho Motion, says charger companies are also starting to produce wallboxes that are ready for bidirectional charging, although he adds it is “still way off being a reality” on a large scale in part because of questions over what technology will become standard.

Nobody knows quite how the money from the valuable service of grid balancing will be divvied up, and there is likely to be a scramble between companies (and the consumer) over who gets how much of the payback.

“We’re providing the technology in order to get the benefits,” says Nissan’s Friederike Kienitz, who oversees sustainability across markets including Europe.

“There will be the fight over who has access to the customer,” she says, speaking last month at Nissan’s Sunderland factory. However, she argues that early pilots in partnership with energy companies “already prove you have a win-win-win situation”.

There are so many moving parts in the energy transition that it will be unclear exactly how countries including the UK will avoid blackouts. Fiona Howarth, chief executive of Octopus Electric Vehicles, says that business models have not been fully worked out. But she adds that electric cars can help to keep the lights on.

“EVs are really part of the solution,” she said. “They are batteries on wheels.”

There are 1 million electric cars on UK roads . When that hits 10m, Haworth says, “we could literally power the whole of the UK at peak time”.