Vehicle to Grid technology, also referred to as 'V2G', enables energy stored in electric vehicles to be fed back into the national electricity network, otherwise known as the grid, to help supply energy at times of peak demand.
It’s considered a real game-changer in the electric vehicle space, because this two-way transfer not only encourages a more active way of consuming energy, it could open up new income streams for drivers, fleet operators and even vehicle manufacturers.
The reason it works is because of the inherently low utilization rate of private vehicles. We may drive our electric car to and from work, or collect the kids from school, but for most of the time, this big battery on wheels is an asset just sitting there… on the street or on your driveway.
Most people are only using a fraction of their battery capacity, and that means there’s a huge amount of spare, stored energy that could be providing services elsewhere. Services such as supporting local energy distribution utilities, or mitigating the intermittency of renewable energy. And imagine if you could make money from these services when your car is just doing nothing at home?
Initially, Vehicle to Grid is actually Grid to Vehicle, as the car takes energy from the National Grid to charge up. When the battery is full, an inverter is able to move energy from the car, back to the grid, when there is demand and when the owner is willing. You can set limits on how much charge can be withdrawn, to ensure you’re never left with an empty battery.
The effect of one EV providing this kind of energy transfer is negligible, but if potentially millions of these mobile batteries could be deployed in an instant, they’d become the biggest future asset for all national transmission systems.
Energy Networks want this technology to work, too, because in order to reduce the impact of climate change, each country is shifting its energy mix in favor of more renewables, which creates volatility. Regardless of whether the wind is blowing or the sun is shining, the grid needs to remain balanced, and without Vehicle-To-Grid, energy has to be bought from reserve power plants, which means more pollution and increased energy prices during peak hours. But if the energy from millions of car batteries can be aggregated and managed to work alongside the grid, it won’t need to rely on more central power plants to fix any constraint issues.
If you think this is all a bit future-gazing, think again. There are already large scale commercial projects underway in Utrecht where car-sharing projects are able to both support and make money from the grid, while Amsterdam’s national football stadium also features a large number of V2G car spaces.
And while most V2G trials currently underway use CHAdeMO connectors, AC bi-directional charging is also being developed.
But doesn’t excessive cycling cause a vehicle’s battery to degrade faster, I hear you ask? Not necessarily. The single biggest degradation to a lithium-ion battery is time spent at full charge, and with V2G, you’re allowing your car to move to a lower state of charge and get paid for it.
Secondly, the rate at which you charge or discharge energy from the battery is an important factor, and anode health can actually be improved by low power, high-frequency cycling, which is how V2G energy transfer is managed.
So V2G is a force for good, not only in providing a quick and cost-efficient form of local energy storage, but developing a more democratic energy system where everybody can benefit.