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How will the grid cope with the addition of electric vehicles?

Posted by John Thompson on 14 November 2018 at 8:09 am

The future of cars is electric. Globally, governments are laying out plans to end the sale of petrol and diesel powered cars, while falling battery prices will contribute towards making electric vehicles (EVs) more affordable and more profitable. With a range of technology on the market, it’s important to find the make and model that’s right for you. But the question remains of just how our national grid will cope with the addition of electric vehicles.


As you would expect, plugging thousands of power hungry cars into the electricity grid will cause an increase in the countries’ demand. A recent Ofgem report estimates peak electricity demand will increase by a further 8MW by 2030. To put this into perspective, this is double the maximum output of our largest power station, DRAX. Although this might sound like a lot, it is only an increase of around 12% of Britain’s current peak demand, and we have roughly 12 years to find it.


Generating this additional power is however, only half the story. The infrastructure that transports the power to our homes and businesses will feel the strain the most. This infrastructure is referred to as the Low Voltage Network (LVN). The same Ofgem report estimated that 32% of Britain’s LVNs will need replacing at a cost of £2.2bn. Building new power stations to meet demand is no easy task, but the logistical nightmare of replacing thousands of miles of buried cable up and down the country is something that is well worth avoiding. Some electricity operators such as Western Power Distribution (WPD) have run trials which recruit owners of EVs and plug-in hybrids which include a free smart charger for participants – keep an eye out to see if any of these are happening in your area.

Smart Charging Technology and Pricing

Smart charging technology may form one part of the answer. This technology allows chargers to reduce the amount of power they send to the cars batteries when they sense the LVN in that particular area is nearing maximum capacity. This not only prevents blackouts but will also reduce the amount of investment needed in LVNs as charging can be delayed to a time when there is ample capacity on the LVN. The LVN is never over stressed, it simply works closer to maximum capacity more often. Smart chargers will therefore allow us to make better use of the infrastructure we already have as we can now be flexible with our demand.

The flexibility of demand brings about a whole new era for our power networks and the way power is purchased. Naturally people are going to want to charge their cars when the price of electricity is at its lowest. This is helpful for the countries’ generation capacity as it will help level out the demand over each 24-hour period and we will be able to generate power at its most efficient rate, however, in a world in which flexible demand is chasing low electricity prices, there is an incentive for consumers to charge their vehicles at the same time, this is not so good for the LVNs.  

One way to incentivise people to charge when demand is low, but also preventing everyone from charging at the same time, is to vary the price of electricity at a very high resolution. Variations in pricing would need to be seen on a resolution at least high enough to allow differing prices between substations, but in a perfect system a resolution that can account for differences between two ends of a street would yield the best results. An EV connected to a smart charger could then be charged any time during the night when the price of energy is lowest in that particular area. If this system of localised pricing is rolled out across the country, it could in theory allow for a totally level demand. Levelling the demand is a positive step towards decarbonising the generation network, as more renewable energy streams can be connected to the grid.

As with any new technology, there are inevitably obstacles that must be overcome to allow efficient integration into existing systems. In the case of EVs, once the energy grid adapts to cope with the additional load, the benefits of having flexible demand on the grid will allow more energy to be generated using renewable methods as energy no longer needs to be used at the same rate as it is generated. 

Related articles:

Will Cars Ever Be Fully Green?

Hybrid, plug-in hybrid or full electric car - which one is for me?

Just how green are electric cars?

If you have a question about anything in the above blog, please ask it in the comments section below.

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3 comments - read them below or add one


KeithSComment left on: 5 April 2019 at 5:07 pm

I read somewhere that each gallon of petrol requires 6 to 7 kilowatt hrs in its production.  If we all stopped using petrol that must surely add up to a massive saving on its own.  

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martinwinlowComment left on: 30 November 2018 at 9:13 am

The 'MW' should be 'GW' and the 'peak demand' should just be 'demand' but the 12% is (by my calcs) not far off.  I made it 10% for all cars and taxis and another 5% for all other road-going vehicles (trucks and vans etc).  

Interestingly, Elon Musk (SpaceX, Tesla etc) came up with the same figures a year or so back.  Everyone seems to have forgotten (including the man himself) but Must was appointed the UK's 'Electric Vehicle Tzar' in 2013... I guess he ended up being too busy with other things as that was the last I heard of it.

Also proven by some basic maths is that for the cost of Hinkley Point C, the UK could install enough battery-connected PV to cover the EV demand, simply by using some of the UK's 70 square miles of south-facing industrial roof space.

But where would HMG get its £50 *billion* annual income from vehicle fuel duty from if we're all driving around in EVs?  Especially ones which are using energy made in our own backyards (well, on our roofs, at least)?  You do begin to see why HMG might not be *wildly* enthusiastic about EVs quickly succeeding in taking over from ICE-ones...  Maybe I'm just a cynic.

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dch_controlComment left on: 30 November 2018 at 8:34 am

An interesting article, but I think you have seriously under-estimated the capacity of the Drax power station!  You implied that it has a maximum output of 4MW.  I think you will find it is 4,000MW (4GW).


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