In what is a departure from my usual topics of astronomy and space science, I’ve written a series of posts on the transition to electric vehicles. This is the third in this series. In this post I will discuss the issues of the lack of availability of public charging and the long charge times. To view all the posts in this series, click the link below.
https://explainingscience.org/tag/zev/
Issue: Lack of availability of public charging
More public EV chargers are being installed in the UK. But as the sales of electric vehicles increases then the demand for public chargers is increasing. For the ideal scenario to provide a public charger for every household that cannot have a home charger, to mirror the situation with charging there would need to be around 10 million new chargers in the UK. In reality, such a large number wouldn’t be needed.
Well after the 2035 deadline, when only zero emission new cars and vans can be sold, there will be still a large number of ICE vehicles on the roads. In the UK in December 2024 there were 1.36 million fully electric vehicles, roughly 4% of the total number of vehicles on the country’s roads, and 73 000 public charging points. A ratio of 18.6 vehicles per public charging point.
Suppose by 2040 there are 25 million EVs on the roads. To allow people without access to home charging and people away from home to charge more or when they needed it is reasonable to assume that there would need to be an EV to public charger ratio of ten to one. In this case around 2.5 million public EV charging points would be required.
Source https://www.zap-map.com/ev-stats/ev-market
In larger cities, where land is scarce, there is not enough available space to build large numbers of new charging spaces close to where people live and work.
The most logical solution and the one which has been already adopted (albeit to a limited degree) is to modify some of the parking spaces in: public car parks, on street parking and the car parks at shopping centres, entertainment venues, hotels and restaurants for EV charging. The rules would have to be worked out for what would happen if all the non-charging spaces were taken, and the only free ones were the EV charging ones. Here are some obvious challenges.
- Would a driver of an EV who didn’t need to charge be allowed to park in a charging space?
- Or a car powered by an internal combustion engine?
- Would a driver still be allowed to park in a charging space once charging had been completed? If so for how long? Would they fined if they outstayed their charging time?
To equip a large fraction of the UK’s car park spaces with charging points would take a large amount of investment. Even if there is an existing power supply to a car park, installation of chargers cost about £ 1500 each. So a rough ball park estimate would be £15 billion to add 10 million new charging point. For larger car parks there is also the logistical challenges of supplying the huge amounts of electrical power needed and this is not factored into the costs
Source https://traffordcentre.co.uk/wp-content/uploads/2024/06/Trafford-Centre-Car-Park-Map-25.6.24.pdf
The diagram above shows the layout of the Trafford Centre. It is one of the largest out of town shopping centres in the UK and lies about 7 miles west of Manchester city centre. The core shopping area is surrounded by car parks having spaces for 11 500 cars. Currently only a small number of these spaces have charging points – less than 100 in total. If the car parks were retrofitted so that 25% of the spaces had a charging point, which could charge at 50 kW allowing 50 kWh of energy to be added to a battery in an hour, then the EV chargers in the car park would need 144 000 kilowatts (144 Megawatts) of power if they were all used at the same time. This is roughly 40 % of the output of a medium sized gas-fired power station.
Clearly it would be a significant challenge in supplying such a large amount of power with our current infrastructure. So, there would have to be rationing, e.g. charging at lower rate when a lot of people were charging. This of course would mean longer charging times.
Issue: Time taken to charge compared to filling up an ICE vehicle.
Chemical energy can be rapidly and easily added to an ICE vehicle -you just need to add fuel to the tank. To add four gallons of petrol(gasoline), enough to drive 200 miles, to my Ford Focus (an Astra-sized car) takes about 30 seconds. To add energy to the battery of an EV, a very large electric current must be passed from the charger to the battery. It is not possible to fill up an EV in anywhere near the time it takes to add the same amount of energy into the fuel tank of an ICE vehicle.
The power the charger needs to deliver to charge an EV is.
energy to be added ÷ charging time.
To add 50 kWh of energy to a battery (roughly equivalent in range terms to 4 gallons of petrol) in 30 seconds (0.0083 hours) the power the charger would need to deliver is
50 kilowatt-hours ÷ 0.0083 hours = 6000 kilowatts, a huge amount of power.
If we had a filling station with ten EV chargers running at 6000 kilowatts (6 megawatts), it would need 60 megawatts of power. The infrastructure does not exist to deliver this. And even if it did, an EV battery could not withstand being charged at 6 megawatts.
The fastest chargers in the UK, DC ultrafast chargers, run at around 300 kilowatts. Using such a charger it still takes 10 minutes to add 50 kilowatt-hours of energy – twenty times longer than it takes to add four gallons of fuel to a petrol-engined car. DC ultrafast chargers are expensive to use and are only available at a small fraction of public charging points. Frequent charging at this rate will shorten the battery lifetime.
With a slower charger running at 7 kilowatts, the typical power of a home charger, it takes 7 hours to add 50 kilowatt hours of energy. This is 840 times longer than the 30 seconds it takes to add 4 gallons of petrol. On the other hand I need to make the point that long charging times aren’t an issue for everyone. If someone uses the car so in such a way that they can nearly always charge at home then they simply out of habit charge their vehicle overnight.
In my next post I’ll discuss some more of the challenges the UK will face as it phases out the ICE and moves to electric vehicles.
And finally….
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