Electric vehicles: the UK peak demand challenge

Customer engagement and charging management will be required to reduce the peak demand requirements of electric vehicles.
Published: Fri 21 Jul 2017

Electric vehicles (EVs) are here and their numbers are growing fast – faster than many had earlier predicted.

For example, in Great Britain a new survey by Baringa Partners has revealed that almost one in five people are likely to consider an EV for their next vehicle purchase. This is double the government’s goal for EVs to achieve 9% penetration of the vehicle fleet by 2020.

While projections are notoriously unreliable, with different scenarios for Great Britain out to 2050 varying by tens of millions of EVs, even at the lower levels, the question is: how will the impacts of these EVs on the electrical system be addressed – or indeed is any planning at all being undertaken for what is arguably the most impactful of the new resources on the grid with the new demand they create?

EV predictions

According to National Grid in its Future Energy Scenarios 2017, in all of its scenarios (apart from the essentially business as usual or ‘steady state’) EVs will constitute more than 90% of all vehicle sales by 2050. Notably, of these up to half could be shared autonomous vehicles.

This growth, which could see up to 9m EVs on British roads by 2030 and 25m EVs by 2050 in the greenest scenario (Two Degrees), is fuelled primarily by advances in technology, such as battery capabilities and cost reductions, making them a viable alternative to internal combustion engine vehicles.

This take up rate is assisted by a variety of policy measures that incentivise EVs and discourage traditional vehicles.

So what is the potential impact? The greatest, an annual demand in 2050 of 46TWh and peak demand of 18GW, arises in a ‘Consumer Power’ world, in which consumers’ desire for the latest technology helps drive the growth in EVs but they have little inclination to become environmentally friendly.

Annual demand from EVs under different future scenarios (National Grid Future Energy Scenarios)

Peak demand from EVs under different future scenarios (National Grid Future Energy Scenarios)

These figures correspond respectively to about 11% of the 2050 national demand and an additional 30% on top of today’s peak demand.

In contrast, in the ‘Two Degree’ world in which there is a high level of customer engagement, the annual demand from EVs in 2050 is estimated at about 35TWh and the additional peak demand at 6GW.

In this scenario, all vehicles sold by 2045 are EVs and effectively it ensures that all vehicles on the road are purely electrically powered by 2050. In comparison to ‘Consumer Power’ in which consumers charge their EVs when convenient to do so, often at peak time, engaged consumers charge their vehicles at off peak times.

Impact on electrical system

According to the report, how the peak time demand from EVs is treated has a significant effect on the electricity system.

If left largely unmanaged, as in Consumer Power, it has the potential to be a challenge to the system, but in particular to the distribution networks and for system operators post 2030.

Current peak demand is around 60GW so the additional contribution of 18GW from EVs in this scenario is significant. Its profile has a steep trajectory from the mid-2020s and shows no sustained slowing down throughout the next two decades.

In contrast, a much more modest rise in its peak demand is experienced in Two Degrees. This is achieved by a mixture of high consumer engagement and the rise of shared autonomous vehicles which charge off-peak in central locations.

In all the scenarios it was assumed that at any one time only 21% of the potential consumers who could be plugged in will be, due to natural activity diversity.

Charging infrastructure

The scenarios are intended as “credible pathways” rather than specific projections but they nevertheless point to the dual need for both customer engagement and charging management when it comes to the large scale deployment of electric vehicles.

An assumption in the analysis was that chargers will be smart enabled, i.e. that they can communicate with other devices that will allow consumers, and potential aggregation service providers, to optimise their demand management.

Another key assumption in this latest modelling was that 7kW chargers become the standard whereas previously 3.5kW was assumed. This change has been made as manufacturers are moving in this direction.

The Future Energy Scenarios also comments on two emerging charging technologies.

Super rapid EV charging has the potential to change EV charging demand and infrastructure requirements. For example, centralised charging sites could be built, rather than vehicles being charged at home where super rapid charging could not be provided without significant grid reinforcement.

Inductive EV charging which allows charging without cables or wires, also could mean less charging is required overnight when the vehicle is not in use, leading to different infrastructure reinforcement requirements.

Related Webinar