One of the stock arguments you will hear against the wide adoption of electric vehicles is about how the power supply grid is going to cope with all these high-voltage devices drawing current to recharge. A home EV charging station will require somewhere between 2kW and 7kW when it is replenishing a car battery. If all EVs are plugged in at once, surely the grid will collapse and power stations will be overextended? Dogs and cats will live together, and mass hysteria will break out? But not only is this a complete misunderstanding of EV charging habits, it could be getting things completely the wrong way round. Here’s why.
Nissan Leaf EVs have been designed with the ability to supply electricity back to the grid.
First, let’s give the negative argument some thought. There were about 33 million passenger cars in the UK in 2019, according to the UK Department of Transport, and there were nearly 274 million registered cars in the USA in 2018, according to the Federal Highway Administration of the US Department of Transportation. If all of these are swapped for EVs with batteries with at least 50kWh, and you charge them all at once at 7kW, you could be asking the UK grid to supply 231GW of energy for at least seven hours, and the US grid 1.9TW. UK power stations supplied 86.9TWh in Q1 2020, which is an average of 39.8GW per hour. The USA had a capacity of 1.1TW at the end of 2019.
This is obviously never going to work. There’s not enough capacity on either grid. But of course, it never would have to. One of the big misconceptions about EVs is that you charge them every day like a phone. This also leads to gross miscalculations about how long the batteries will last, but let’s not get into that argument right now. A survey by Statista published in January 2020 stated that in 2017 UK motorists drove on average 4,500 miles per year for private use, and the trend since then has been down. That’s just 12 miles a day, and with lots of EVs now providing a 200-mile range on a single charge, on average you’ll be charging your EV twice a month. So, in reality, assuming an even distribution of charging, the UK grid could easily cope with everyone owning an EV and charging it twice a month on average. American drivers use their cars a lot more – 13,500 miles a year, according to the US Department of Transport. But that’s still only six charging cycles a month for an EV with a 200-mile range, which is well within current capacity.
Average energy usage at different times of day in the USA.
The next stage of the argument is that, even if the grid could cope with EVs if they were the only things needing power, what about everything else? This is where we need to get into actual charging habits. Peak electricity times vary with country and the focus of the local industry. For example, industrialized areas of Germany and China use a lot of energy during the day, but more service-oriented economies tend to require more in the afternoon or early evening. In the UK, the peak is between 6pm and 10pm, and the US is similar, except over the summer months presumably because of daytime air conditioning usage.
But none of these times will be when you recharge your EV. You’re likely to be doing this mostly overnight at home while you’re asleep. This is the period of least energy usage for other activities, particularly between midnight and 6am. In fact, energy is so out of demand at this time that one energy supplier in the UK has actually paid its customers to use electricity for short periods overnight. Most EVs already have the ability to set times when they charge, so you can plug them in before going to bed, but they only start consuming energy at the time you configured. Smart meters are also getting increasingly, well, smart, and can already do things like reduce charging supply when other things in the house need the electricity more.
Vehicle-to-Grid technology allows an EV to supply electricity back to the grid as well as consume … [+]
But there’s one other area where EVs can not only be charged in a way that fits into low-demand slots in the national energy usage cycle, but even provide assistance to smooth out supply at peak times. This is a technology called vehicle-to-grid (V2G). The idea is that you leave your EV plugged into the electricity when not in use, and it can supply energy as well take it. It will basically act like a mobile Tesla Powerwall, a domestic battery that can absorb energy at times of overproduction, and then put it back into the grid during peak demand. This will be increasingly important as a larger percentage of supply is taken up by renewable sources, which tend to be less predictable in when they deliver capacity than fossil fuel or nuclear power plants, which can be more easily turned off and on when required. It’s even more useful if your home has its own renewable energy production.
Nissan has designed its Leaf with this usage model in mind for years. Trials are already taking place in the UK with Electric Nation and Octopus Energy’s Powerloop using the Leaf’s V2G abilities. Nissan is even accepting power as payment for parking at its Pavilion Exhibition space in Yokohama. In the USA, Nuuve and Fermata Energy have also been trialing the idea, and a tear-down of the Tesla Model 3 revealed that it has the circuitry for V2G built in already. Unfortunately, at the moment it is primarily cars with CHAdeMO charging ports like the Nissan Leaf that can supply energy as well as consume it, and the increasingly dominant CCS connection doesn’t currently support this function, although it will by 2025. Nevertheless, rather than being a big unsolvable issue for national energy grids that could take electricity usage over the edge, with vehicle-to-grid technology, EVs could actually make energy supply more efficient by smoothing out capacity. They could be the solution, not the problem at all.
