Locale : Global (English)
Electric cars charging at a charging station on the pavement.

Third dimension

Simon Harrison, Strategic development manager, Mott MacDonald

We’re starting to see electric car charging points on the streets, at motorway service stations and occasionally on front drives. What does the mass-electrification of vehicles mean for electricity utilities?

First you need to understand how electricity supply works at the street level

The average demand of you and your house is about 1.5kW. The way the power system is designed assumes that people along your street are not all having electric showers at once – because people have different habits, power use is diverse and load is spread fairly evenly. But if everyone in your street turned on their electric showers at the same time and left them on for an hour, you’d cook the local distribution system. Electric Vehicles (EVs) are now visible on the high street. If, or when, we hit a tipping point and EVs become ubiquitous, then the local power system is going to be put under intense strain.

What happens when EVs enter the mix?

EVs have a high charging load which is there for a long time. Depending on charge rate, you might have 4-5kW for a slow charge or around 8-10kW of load for a fast charge; in the case of the 4-5kW load you will be charging for several hours. With local cluster effects – people who buy electric vehicles are more likely to have people who buy electric vehicles as neighbours – it won’t be long before we are seeing a large change in electricity demand at the very local level.

How might that be met?

One option is to use a smart grid to control the timing of charging and to offer variable tariffs to incentivise charging when the neighbours aren’t. If the network companies invest in smart technologies, for a while at least, we won’t need to put a lot of additional cable in the ground to provide more capacity.

How far will that get us?

The issue is scale. If you electrified the whole of the UK vehicle fleet, you could be doubling national electricity demand. Additional generating and transmission capacity could be provided but at a hefty price and involving much disruption.


Yes, but there’s an alternative scenario. As others have pointed out, there are technological and social revolutions afoot. If automation converges with sharing and people don’t own their own EVs, it may take pressure off the power grid.


The key question is where are autonomous shared vehicles going to get their juice? The chances are that the fleet owner-operator will do a deal with somebody who has land and a stiff grid supply point next to it. It might be the local supermarket car park or a piece of land next to an electricity substation. What they won’t do is charge up outside people’s houses.

How likely is this?

The bit that nobody has really got to grips with yet is how society is likely to react to that opportunity and what proportion of the population are going to take it up. You’ll probably have buy-in from all the people who aren’t independently mobile at the moment, such as the elderly, the disabled. Young Millennials and the Noughty generation are less fixated on owning stuff and might go for it. Maybe the middle aged might still want to own a vehicle, but maybe not if the price is right.

How far and how fast?

It’s a fair bet that it will be dictated by consumer instinct. People’s preferences can shift extremely fast. Someone like Uber might do a deal in a major city to supply shared autonomous vehicles and facilitate change almost overnight. This is at complete odds with the behaviour of utilities that operate to committed spending plans, within a regulatory cycle. They’re not set up to react swiftly to disruption and there’s a real risk that, if they make the wrong investment decisions, they’ll have redundant kit and stranded assets.

If you were a betting man?

There will be early adopters, although this one is likely to have an enormously long tail. In a slightly counter-intuitive way, a slow pace of change could be worse because more will have been invested in today’s solution when the disruption finally happens.

Simon Harrison

Group strategic development manager

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