Dr Euan McTurk, Plug Life Consulting Ltd – Part 1 of 2
What if I told you that, potentially, you could power your house using your electric car? And what if I told you that some EV drivers amongst you who are reading this could do this today? And what if I told you that, no sooner than this amazing tech was developed, the automotive industry set it back by at least a decade by immediately trying to reinvent the wheel? Welcome to the story of Vehicle-to-Grid.
The computer on which I am writing this article is being powered by my electric car. I’m doing the laundry as I type this, too, and my smart meter hasn’t flinched at all. That’s because I’m one of the lucky few people in the UK to have a Vehicle-to-Grid charger that I can use with my Nissan LEAF. It sits at the back of the driveway, not doing much to the naked eye, but in reality, it hoovers up excess electrons from my solar panels during the day and uses them to power the entire house during the evening and overnight. Cooking, working, cleaning, entertainment, heating and hot water are solar-powered, 24/7. On cold, dark winter days, when the solar panels aren’t up to much, the car charges overnight off of super-cheap off-peak electricity and uses that to power the house for the entire day, saving 70% vs the peak-time electricity tariff that would otherwise apply during the day and evening.
However, this setup isn’t anywhere near as commonplace as it should be. I’ll explain why later, but first, let’s look at the different variants of Vehicle-to-X that some electric vehicles can do today.
V2X: what are the differences?
“V2X” encompasses the different ways of using an electric vehicle’s battery to power something other than the vehicle itself. The most basic version is Vehicle-to-Load, or V2L. This is where the vehicle has a domestic power socket, either built into the car or on a special adapter that plugs into its charge port, that allows you to power appliances from power tools, to lawnmowers, to camping stoves. During the series of EV reviews that I did with Ric Boullemier and Generate Media for the FASTER Project, we used V2L to play Mario Kart on the dashboard screens of the wonderfully eccentric Honda e, and took the Hyundai IONIQ 5 and Kia EV6 to Whitelee wind farm for an EV-powered picnic. V2L is particularly commonplace on new MG, BYD, Hyundai, Kia and Genesis EVs these days, and there are already tales of people using V2L to power essential devices during blackouts at their homes.
“V2H,” or Vehicle-to-Home, takes this further by allowing the car to power your entire house (up to the car’s maximum power limit) via a home charge point. Rather than having to plug your electrical devices directly into the EV, the EV plugs into the home charge point as normal, which then sends power to your house. The process is automatic, and you don’t notice the difference between electricity coming from the vehicle or from the grid.
V2G, or “Vehicle-to-Grid,” typically uses the same setup as V2H, but instead of only being concerned about powering the house, the EV can be used to export electricity to the grid, which can help to stabilise the grid during peak times and reduce the need for fossil-fuelled power plants. Some electricity providers like Octopus already have experimental electricity tariffs that reward EV drivers for providing excess energy in their EV batteries to the grid when required.
According to the RAC Foundation, there are 33.58 million cars in the UK. If just 10% of them were V2G-capable EVs plugged in at home, and capable of delivering 7 kW of power each, then this would provide over a whopping 23 GW of dispatchable power on tap – that’s over ten times the maximum power of Pembroke B, the biggest gas-fired power plant not just in the UK, but Europe. The UK rarely uses more than 50 GW of power, even on the coldest of winter days.
Isn’t V2G all a bit Big Brother?
Far from the scare stories that some tabloids have ran about the government telling you when you can charge your car, or draining your car overnight and leaving you with a flat battery, when V2G is fully commercialised, it will allow the EV driver to state the minimum charge that they need in their battery and the time by which they need it, e.g. “You can take as much energy as you want when I plug in after returning home from work this evening, but make sure that my car’s battery is at least 70% full by 8am tomorrow.”
The driver would then be rewarded with payments for the electricity that they exported that evening, and a cheaper charge overnight using off-peak electricity, simultaneously saving them money and making them money. I have already taken part in experimental (and entirely optional) grid balancing sessions that have paid me up to £4 per kWh (vs 30p for my peak-time tariff) to export electricity from my LEAF’s battery at specific times of the evening over winter. The gamification and reward of these sessions makes them quite good fun to participate in, and should ensure high levels of uptake once V2G becomes mainstream. I should note that, if I needed to charge my car urgently during those peak time grid balancing sessions, I would have been able to do so without issue or financial penalty.
Will V2X harm the battery?
Some people are understandably concerned about V2X’s impact on their EV’s battery health. If the battery is being discharged more often, won’t it reduce the battery’s lifespan? On the contrary, some very talented former colleagues of mine from WMG (Warwick Manufacturing Group, University of Warwick) conducted a thorough study on V2G over a period of two years.
They took commercial lithium-ion cells that you would find in EVs and put them in thermal chambers that simulated environments from around the world, from Cairo in Egypt to Anchorage in Alaska. Some of the cells underwent simulated EV driving cycles during the day, and were charged at night, while others did EV driving during the day and then V2G duties when the simulated EV was at home. The study found that V2G can actually extend the lifespan of EV batteries by 10%. The reason for this is twofold: 1) the battery spends less time at very high State of Charge; the NMC cells found in most EVs today don’t like sitting at close to 100% SOC for long periods of time because it causes them to degrade (albeit very slowly), and 2) V2G cycles are much lower power and more constant than the high power, dynamic charge/discharge cycles that the battery experiences when powering an EV: compared to harsh acceleration, regenerative braking and rapid charging, V2G is a walk in the park. If V2X was seriously detrimental to the battery, I wouldn’t use my LEAF to power my house.
So, why isn’t everyone already doing V2G today? We’ll look into this in part 2.
Stay tuned for part 2, and in the meantime, catch up with all of our fantastic guest editor articles, here.
