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What is vehicle-to-grid or V2G?

Last updated on 16 September 2019

And what if electric cars could be used to store electricity, as well as carrying us around? This is the idea of 'vehicle-to-grid' or V2G.

This technical concept is based on the idea of using the batteries in parked electric cars in both directions and with flexibility to:

  1. take in and store electricity that is produced in excess on the network;
  2. constitute an electricity reserve to power the grid or a home network when needed.

What is the point of vehicle-to-grid?

The electricity grid must always stay in balance, otherwise you get blackouts. With the development of renewable energies, with very variable production, management of this balance has become more and more complex.

In other words, V2G is one solution, among others, so that we can make the most of the renewable electricity that is produced and better manage fluctuations on the electricity grid.

Does the vehicle-to-grid have potential in Belgium?

In 2040 there will be between 900,000 and 2.5 million electric vehicles in Belgium alone. This is what a study by Elia, the Belgian transmission system operator, reveals. 

However, we know that cars, whether electric or not, spend much more time parked than driving around. We would end up with hundreds of thousands of electric cars parked for one hour or a whole night.

Connected to their terminal and with a full battery, these cars would therefore make up a huge reserve of electricity. The potential of "wheeled storage" is therefore very real.

Many projects are at a study stage around the world, including, close to home, in Amsterdam. However, it will still be a few years before this technology is mature enough and can be used.

A good idea, but not without smart technologies

To work properly, vehicle-to-grid must consider:

  • the needs of the car drivers: in the morning, they must be able to rely on enough battery autonomy, for example to get to work
  • moments when renewable electricity is produced in excess: mid-day in summer for solar panels. When winds are strong, especially in winter and at night, for wind turbines
  • peaks in electricity demand: in Belgium, in the morning around 8:30am and in the evening from around 6:00pm to 7:00pm
  • electricity prices: car batteries could also provide houses with cheap electricity instead of allowing households to consume electricity at peak times in the morning or evening.
To achieve this, 'smart charging' will have to be used, which is a concept that complements V2G. It is based on the use of smart meters, a smart network and also smart charging stations. These technologies would in particular make it possible to automate priority management.

A second life for electric vehicle batteries

Batteries from electric vehicles will be added to the home battery bank which develops in parallel.

Car batteries do, in fact, gradually lose their capacity. After a few years, this capacity is no longer sufficient to provide enough autonomy for a car, but the battery’s performance is still sufficient to power a building’s electrical system.

It is therefore expected that a secondary market will develop for 'retired' car batteries as home batteries.

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