Electric cars. Will they cause blackouts?

The switch to electric cars will increase demand on our electricity infrastructure. Which leads some people to ask whether it will be ok to charge our cars and boil the kettle at the same time, without causing a blackout.

7 September 2017
 

According to a recent report by Bloomberg, sales of electric cars will likely overtake sales of petrol and diesel cars in the 2030s.

When this happens, the switch to electric will increase demand on our electricity infrastructure. This concerns some people as it could cause local or even national blackouts.

But is this really the case? Will we be able to charge our cars and boil the kettle, at the same time, without blowing the fuse?

Let’s start with the facts. According to the latest projections, in the UK, electric vehicles will lead to an additional peak demand on the National Grid of approximately 5 GW, a total overall increase of 8% on the current figure.

An 8% increase in demand for electricity isn’t likely to put the lights out. This would only happen if all the new electric cars were to be charged, at home, at the same time and during peak periods, creating an additional and temporary surge in the peak demand for electricity of approximately 50%.

This is an extremely unlikely scenario for three key reasons.

First, energy demand is not constant: it peaks at around 5 pm and troughs in the early morning. Therefore, the idea that we would all suddenly want to start charging our cars during expensive peak periods and overload the grid is extremely unlikely.

Second, with the development of increasingly “smart chargers” and “flexible grids”, which communicate via the internet, cars will be able to autonomously charge during dips in demand to restrict any additional load. Since the price of electricity fluctuates with demand, drivers will be incentivised to charge their cars at night, when demand is lowest, and save money. New smart charging solutions, such as Tesla’s Powerwall, already make this possible.

Third, to fully charge an EV at home in a reasonable time, special charging equipment is required – these have a power rating of around 7 kW and provide up to 25 miles of range per hour however; these chargers are not required by most since 95% of daily journeys are under 25 miles. This level of range is achievable with 6 hours of charging in a standard socket – reducing the strain on the grid by lengthening the charging period. For those undergoing longer commutes, 7kW chargers need 30 amps of current, leaving at least 30 amps for use by other appliances. Most appliances operate on a low current, meaning you would be safe to charge your car and go about your normal business at home without blowing the main fuse – avoiding blackouts.

In short, the increased adoption of electric vehicles will not cause blackouts: we are confident that, in 2035, you’ll be safe to charge your car AND put the kettle on.

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