Using electric vehicles for energy storage

Electric vehicles (EV) are now a reality in the European automotive market with a share expected to reach 50% by 2030. The storage capacity of their batteries, the EV’s core component, will play an important role in stabilising the electrical grid. Batteries are also at the heart of what is known as vehicle-to-grid (V2G) technology. 

We take a deep dive into this fascinating technology, including its opportunities and challenges. 

Photo credit: DREEV

The big picture: a grid under pressure 

All day, every day, the electrical grid must be kept in balance, and at the right frequency. This means matching generation to consumption needs in real time. In France, the transmission system operator in charge of this balancing act is RTE.  

Today, when it comes to electricity generation, we can talk about two kinds of energy: 

Controllable energy is the energy that comes from nuclear power plants, coal-fired plants, gas power plants, and hydroelectric dams. These are energy productions that can be activated, switched on and adjusted in power more or less rapidly according to demand. When there are peaks in consumption, the fastest units such as gas or hydroelectric power plants are activated to meet this demand. 

Non-controllable energy is the intermittent energy generated by wind turbines and solar panels and is contingent on the wind blowing and the sun shining. It is also renewable energy, meaning that it meets the objectives of the energy transition. But because these energy sources cannot generate power on demand, it is harder to use them for balancing the grid, which can have an impact on the cost of electricity.  

How can EVs help balance the grid?  

The solution: V2G and V2H 

V2G: Vehicle-to-Grid  

With V2G technology, electric vehicles will be able to inject electricity back into the local grid when overall demand is at its highest:  

“Charging becomes a bidirectional process, meaning the network no longer simply supplies the vehicle’s battery with electricity: it also considers this battery as a power source to be used to meet various energy consumption needs.” – Renault Group  

For the vehicle the battery capacity is low, but it can be a highly valuable energy reserve both locally and even internationally by helping balance the grid.  

V2H: Vehicle-to-Home 

The EV battery also has the potential to be a mobile storage device. Most cars are used for the daily commute between home and office, but 90% of the time they are parked. This downtime is the perfect opportunity for recharging during off-peak hours, when overall demand and the price of electricity are at their lowest. This is usually: 

• At night — from midnight to 4 a.m. (super off-peak hours), from 10 p.m. to midnight and from 4 a.m. to 6 a.m. (off-peak hours) 
• During the day — between 1 p.m. and 5 p.m. is also an off-peak window, which also happens to be when the sun’s rays are strongest  
• When solar and wind generation are at their peak (price signals will in the future be detected by smart meters, like Linky in France) 

Users can then use the energy stored in their EV battery to power their homes for an hour or two. They can also charge their EVs when the cost of electricity is at its lowest, and feed some of the stored energy back into the grid when the cost of electricity is at its highest. This means the user will pay off-peak rates to recharge their EV instead of peak rates, with the added bonus of lower household consumption during peak hours, helping to bring down demand during that same window. 

EV batteries have a capacity of between 50 and 100 kWh. A daily commute (home-office) consumes between 15 and 20 kWh for a distance of 100km. In France, households consume a daily average of 13 kWh of electricity. A 50m2 apartment for two people that has electric heating consumes around 30 kWh over an entire day. Clearly, there is an opportunity to use V2H in France for injecting power back into households during peak hours. 

V2G and V2H technology can also be used to balance generation and demand, regulate non-controllable energy sources, and lower the electricity bill for the end-user. 

So, what’s holding back the deployment of V2G? 

V2G technology is not yet widely available simply because the EV market is still in the development phase. However, the market is set to grow substantially between now and 2030 by which time, according to the International Energy Agency (IEA), between 40 and 65 million EVs will be on the road in Europe — 10 to 15 million of which in France. Just imagine the energy storage capacity of this many batteries! 

According to the position paper of the European Association for Electromobility (AVERE) France on V2X (i.e., all bidirectional charging technologies), developing these systems will require changes to technical and legislative frameworks in order to:  

• Add V2X systems to charging stations  
• Factor in the needs of EV drivers (who expect enough range for their daily commutes), peak demand, and the cost of electricity.  
• Allow owners to make their EV available for V2G purposes 
• Incentivise private users to participate by adapting the transmission network access tariff (TURPE) and the calculation of their final energy consumption in order to reward their efforts. 

Large-scale V2G technology tests and experiments  

V2G testing on the energy requirements of buildings, neighbourhoods and houses is currently underway in France. Starting in early 2021 in the Occitane region, the Flexitane project run by the Ad’Occ agency, Ademe (the French Environment and Energy Management Agency) and EDF, is a full-scale test of a V2G bidirectional charging station service. The data collected will be used for the deployment of the technology.  

The Renault Group for its part is now developing its V2G solutions after running full-scale experiments on bidirectional and alternating-current EV charging in the Netherlands and Portugal. Nissan, Mitsubishi and other manufacturers are also offering V2G services for companies using CHAdeMO technology (direct-current bidirectional fast charging). 

The central role of battery manufacturers in energy storage 

The storage capacity provided by EV batteries is paramount for integrating renewable energy into the grid, be it via stationary storage or V2G technology. In the future, this solution will also increase the share of renewables in the French and European energy mix.  

However, manufacturing electric battery cells is very energy-intensive and has to have a competitive edge over competition from outside Europe. The growth of the e-mobility market is accelerating, international competition is steepening, and stakeholders are determined to bring manufacturing back home.  

This is why manufacturers need the means and the support to lower the cost of electricity. The current energy crisis has also raised the stakes, and more than ever battery manufacturers must have access to large quantities of cheap, decarbonised electricity in order to successfully set up in Europe and start producing low-carbon cells at an industrial scale. 

Energy providers need batteries as much as battery manufacturers need energy. This is also why a number of battery manufacturers and European utilities have already banded together to form associations.  

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By storing and dispatching energy to help even out the demands on the grid, V2G technology offers a clear opportunity to better incorporate non-controllable, renewable energy into the grid, and be part of the solution to combat climate change.  

Verkor has chosen to focus on high-volume battery-cell manufacturing for the electric vehicle and large-scale stationary storage markets (see more).