Understanding the impact of EVs on electricity networks

Transport electrification is one of the key routes to decarbonisation.  The impact on the electricity network is sometimes cited as a barrier to this change.  In this article we explore the drivers behind the electrification of transport, and the results of a trial, delivered by EA Technology in partnership with Drive Electric, for Western Power Distribution, which demonstrated how this can be achieved while still ‘thinking of the network’. 

The transport sector now accounts for the largest share of UK energy consumption by sector. However, there has been no significant reduction in emissions from transport since 1990. 

Data source: https://www.gov.uk/government/statistics/energy-consumption-in-the-uk

Data source: https://data.gov.uk/dataset/9a1e58e5-d1b6-457d-a414-335ca546d52c/provisional-uk-greenhouse-gas-emissions-national-statistics

What’s happening now?

There’s significant policy support for EVs to help achieve Net Zero. The government is encouraging consumers to switch petrol and diesel cars and vans for battery electric vehicles through various measures:

• EU level binding emission targets for new vehicles apply to manufacturers
• Ban on the sale of new internal combustion engine-powered vehicles in 2030 (previously 2035)
• Purchase subsidies for battery electric vehicles
• Grants available for individuals and businesses installing charging points
• Attractive benefit in kind tax rates for EVs (compared to petrol/diesel cars)

Here in the UK, sales of battery electric and plug-in hybrid vehicles are increasing. But there’s a problem that goes hand-in-hand with that: the Road to Zero could increase today’s energy consumption by around 30% by 2050. So what about the electricity networks? 

Data source: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/942102/veh0253.ods

Source:  Table 4.18 http://fes.nationalgrid.com/media/1432/fes-data-workbook-v30.xlsx

Source: https://www.lowcvp.org.uk/projects/electric-vehicle-energy-taskforce.htm

Getting ready to take the pressure

There have been plenty of scare stories in the mainstream media about electricity networks’ ability to cope, but the industry has been preparing. The National Grid has been busy modelling impact at a system (national) level to show how tariffs could reduce the increase in peak demand as vehicle owners charge their EVs. Energy suppliers are experimenting with time-of-use tariffs to EV drivers that reward them for charging off-peak, too.

The development of standards so EV chargers have smart technology built in, coupled with engagement with consumer groups about smart charging, is starting the process of education about when to charge EVs. Distribution networks are modelling where they will need to be reinforced so that they can plan extra capacity. At the same time, they’re improving the connection process for charge point operators, making it quicker to get a connection, and changing design standards for new houses are helping to future-proof the network.

Exploring the future through Electric Nation

Innovation projects are critical to understand what demand EV charging will create, and they have also allowed network operators to trial of smart charging with customers to prove feasibility and acceptability. Western Power Distribution’s Network Innovation Project Electric Nation

was one such initiative developed to address the challenge of increasing demand on distribution networks from the electrification of transport.

Delivered by project partners EA Technology, Drive Electric, TRL and Lucy GridKey between 2016 and 2019, Electric Nation aimed to:

• Expand understanding of the impact of domestic EV charging on distribution networks (range of vehicles, up to 7kW charge rate)
• Increase understanding of charging behaviour for different vehicle types
• Evaluate technical feasibility and customer acceptance of smart charging solutions to manage additional demand

The field trial

The two-year field trial included 673 participants and more than 130,000 charging events. Smart charging in Electric Nation involved sending signals to slow charging down when necessary or using tariffs to encourage drivers to charge outside of peak times

What we discovered about demand management

We wanted to determine whether it would inconvenience drivers if charging were slowed down, for example during the evening peak), whether or not participants would accept this, and how they would respond to time of use tariffs..

Data from the trial showed that cars are generally plugged in for much longer than they need to charge for, particularly when they are plugged in the evening.  This is because, in most cases, the car is plugged in overnight.  This means that there is flexibility in the charging – it can be slowed down and still be fully charged when the driver next wants their car. 

Data from the trial showed flexibility in charging. However, without an incentive, EV charging could create additional demand in the evening peak which would sometimes be greater than the network capacity – particularly in winter when other demand is also high.  Demand management through smart charging could be a solution to this. The trial showed that demand management  was technically feasible and acceptable to the majority of participants –satisfaction scored by participants remained high and was not linked to the amount of management they experienced. 

The final part of the trial looked at whether a Time-of-Use incentive supported by an app and smart charging could reduce the additional demand created in the evening peak.  This approach was highly effective at moving demand away from the evening peak. During this trial there was always enough capacity available for those who wanted to charge in the evening peak.  Engagement with the app was high, with 61% of participants using the app.  Satisfaction remained high, and 76% of participants would recommend the app and tariff to their friends.   

Summary 

So what does this all mean? There’s plenty of work underway preparing electricity networks for transport electrification.  Electric Nation is one example of this.  It showed us that smart charging is something that works well for EV owners: moving the charging load to times when networks are less used (i.e. during the night) means lower energy costs for all users. Smart charging does not inconvenience drivers – and providing them with a smartphone app means they are always in control of their charging schedule.

Resources for further reading 

Download Electric Nation reports:

Electric Nation Report

Find out more about other EV projects: