National Grid has welcomed the plan to make electric or zero-emission cars account for all new car sales from 2040, but said the government and industry now faced big decisions on how the extra power was generated and demand for it managed.

The grid recently warned that by 2030, electric cars could require 3.5-8GW of additional capacity, on top of the current peak demand of 60GW. By the middle of the century, it is assumed nearly all cars will be electric, extra peak demand could be up to 18GW.

The lowest estimates of extra demand assume that drivers charge their cars at off-peak times. Smart meters and time-of-day tariffs could incentivise owners to charge when wind and solar power are plentiful and electricity is cheaper.

National Grid said the extra power would be generated from gas, wind farms, imports and nuclear reactors – not from coal, which is scheduled to disappear from the UK’s power mix by 2025 at the latest.

And the switch to electric vehicles could even provide an eventual boost to the grid…

The UK plans to invest millions of pounds to explore how the batteries in thousands of electric cars could help power the grid and drive take-up of cleaner vehicles.

Known as ‘vehicle-to-grid’, electric car batteries could provide services to local power networks and National Grid – returning electricity to the grid at times of peak demand, or filling the gap if output from wind farms or solar panels were suddenly less than expected.

Drivers also stand to benefit as they would be compensated in some form – such as via payments or free parking – for allowing their batteries to help power grid managers.

Jesse Norman, a transport minister, said: “Electric vehicles are already helping thousands of motorists cut their fuel costs, and now there is an extra financial incentive for motorists to go green.”