How will the UK cope with the expected uptake of electric vehicles? Here are the four key impacts it may have on the national electricity network and generation.
Can power network absorb the anticipated increase in the number of electric vehicles?
Some media outlets have reported that the extra electricity which will need to be generated for the widespread use of electric vehicles will be the equivalent of building 10 new nuclear power stations.
They have used a National Grid scenario which predicts that an extra 30GW of electricity would need to be generated to meet potential demand in 2040.
At the moment, around 100,000 vehicles in the UK are plug-ins – either fully electric or plug-in hybrid models.
“This works out at around 0.05% of our power as an average over the year, so it’s barely a blip on the dial for the energy system to cope with,” says Mark Thompson, innovation lead – energy systems at Innovate UK.
“If we get to a scenario of 100% EV penetration of around 30 million vehicles which is the current car parc size, then according to one National Grid scenario, that’s something like 11% of UK power.
“That’s a lot of energy. That’s many billions of pounds of money flowing into vehicles in the future.”
Between January 2013 and December 2015, EA Technology oversaw the My Electric Avenue project which investigated the effect that clusters of electric vehicles being charged has on local electricity networks.
Mark Dale, innovation and low carbon network engineer at Western Power Distribution, says the project came to the conclusion that if the UK had a 30% penetration of EVs, then the improvement work needed to the infrastructure would cost around £2.2 billion if charging habits and technology remained the same.
However, the National Grid says the figure of 30GW has been taken out of context: it was calculated for an unlikely but possible extreme set of circumstances, including that all vehicles on the road were fully electric and that charging technology and habits remain unchanged.
Instead, National Grid estimates that a more realistic prediction is that the peak demand from electric vehicles alone will be around 5GW, an 8% increase on today’s peak demand value.
This figure assumes that charging habits and technologies will evolve.
What is smart/managed charging and how can it help?
Smart charging can reduce levels of peak demand on the electricity network by using technology to determine when vehicles are charged.
This means vehicles can draw power when demand on the network is low, meaning overall demand doesn’t exceed network capacity, with the vehicle still being fully charged when the driver goes to use it.
The Electric Nation trial has identified the peak in EV charging begins at 5pm, which could cause issues for the existing power network.
Based on a 30% penetration of EVs, “at certain times of the day in winter we are going to exceed the network capacity, so we have got to move that winter peak away and into an area where we’ve got the capacity already”, says Mark Dale, innovation and low carbon network engineer at Western Power Distribution.
“We see that smart charging could reduce, delay or even avoid the need for any of those reinforcements, certainly in the short term.”
Esther Dudek, senior consultant at EA Technology, adds: “What’s interesting is not how long the vehicles are charging for, but how long they are plugged in for.”
Electric Nation found that the majority of EVs were plugged in during the early evening and left overnight until they were needed the following morning.
Its data showed the vehicles began charging as soon as they were plugged in, meaning they were still connected for several hours after they are fully charged.
“By using smart charging we can get more electric vehicles out there on the networks without needing reinforcement works which are both disruptive and potentially costly,” adds Dudek.
What is vehicle to grid?
Vehicle to grid (V2G) is a system which could help meet electricity demand and earn the vehicle operator money.
It effectively allows an electric vehicle to work as a small scale generator and export power back on to the network.
This will give additional flexibility beyond smart charging, as it decentralises electricity generation, says Esther Dudek, senior consultant at EA Technology.
It also provides the company or driver which operates the vehicle with a potential revenue stream.
“One analysis suggests that it could equate to somewhere in the range of £200 to £2,000 of value per annum,” says Mark Thompson, innovation lead – energy systems at Innovate UK.
“If you have an EV plugged in, pushing 7kW into the grid at peak hours, that’s a pretty useful amount for the network to have. 7kW is equivalent to driving along at 19mph, so vehicle to grid is a pretty unstressful task to perform.”
Fears that extracting energy from EVs with V2G technology causes their lithium-ion battery to degrade more rapidly have proved misplaced, according to research from the Warwick Manufacturing Group (WMG) at the University of Warwick.
It actually found V2G could reduce capacity fade by up to 9.1% and power fade by 12.1% over a year.
Battery degradation is dependent on calendar age, capacity throughput, temperature, state of charge, current and depth of discharge, making V2G an effective tool that can be used to optimise a battery’s condition so that degradation is minimised, says the university.
Kotub Uddin, lead researcher for sustainable energy and environment at the University of Warwick, says: “These findings reinforce the attractiveness of V2G technologies to automotive manufacturers: not only is vehicle-to-grid an effective solution for grid support – and subsequently a tidy revenue stream – but we have shown that there is a real possibility of extending the lifetime of traction batteries in tandem.”
Are the environmental credentials of electric vehicles harmed by how the electricity is generated?
Yes, although the amount of electricity generated by low carbon sources in the UK is growing.
The National Grid says that between late June and September, 52% of electricity generation was met by low carbon sources ranging from renewables, such as solar and wind, to nuclear power, compared with about 35% four years ago.
Almost a quarter of power generation (24%) came from renewables this summer, up from just 9% four years ago and 20% last year.
Average CO2 emissions for each unit of power fell by more than 56% between summer 2013 and 2017 as more electricity came from low carbon sources and polluting coal is increasingly used less.
In summer 2013, 491g of CO2 was produced for each kilowatt hour of electricity, but the average figure for this summer was 216g per kilowatt hour.
These figures cap a landmark year for solar in the UK, with generation reaching new heights within the energy system.
In May, a record-breaking quarter of Great Britain’s energy demand was met by 8.7GW of solar power that was supplying electricity to the grid, while just days later renewable power met more than 50% of the nation’s electricity supply.
Large amounts of solar along with wind and nuclear power later pushed Great Britain’s carbon intensity to record lows of around 90g of CO2 per kWh.