“As early as 2030, batteries in electric vehicles could fully meet the need for short-term electricity storage around the world. By connecting them to the power grid they can provide their stored energy, improving energy security and enabling renewable technologies in cleaning the grid.
Researchers from the Leiden Institute of Environmental Sciences (CML), in collaboration with the US National Renewable Energy Laboratory, published a paper on these opportunities in Nature Communications on January 17.
Replacing petrol vehicles with electric ones may be good news for the energy transition, but there are big challenges in avoiding an overloaded grid and meeting demand. With the right approach, electric vehicles can enable the energy transition by smoothing the daily variability in renewable energies like solar and wind.
Charging and returning power
Electric vehicles can be thought of in terms of transportation, but they are also energy storage devices. With the right technologies and coordination, they can be charged when there is plenty of wind and sun and discharged when the demand is high on dark and windless days.
Imagine returning home with an 80% charge on your car’s battery, plugging it in and allowing it to power the grid during peak electricity demand as people come home to cook and relax. A smart device would intelligently discharge and charge the car during the night if demand is low and the wind strong, ensuring you have plenty of charge for the next day’s drive to work. At work you can charge again while the sun is shining.
A car’s storage capacity
Lead author Chengjian Xu and colleagues examined the extent to which vehicle batteries can meet the need for short-term electricity storage. While acknowledging that they do not know for sure how our driving behaviour will evolve or what innovations lie ahead in battery development, they used an integrated model and looked ahead to 2050. They accounted for several trends and limitations, such as the growth of the electricity vehicle market, people’s daily driving habits and climatic impacts on battery degradation. ‘This allowed us to calculate the storage capacity,’ says Xu, who will conduct research on circular solar panels at Delft University of Technology after his recent PhD in Leiden.
An extra life for batteries
The researchers also included the use of batteries after they are no longer good enough for driving. Bernhard Steubing, a senior author on the work, notes: ‘Once the capacity of vehicle batteries has decreased to about 70 to 80 per cent, they are typically not good enough for vehicles but are still good enough to be used for power storage and delivery within the grid. We can take them out of vehicles and give them an extra life in stationary storage on the grid.’
The researchers found that batteries could fully meet short-term power storage needs as early as 2030. And not everyone has to join in. Only low participation rates of 12%-43% are needed to provide short-term grid storage demand, depending on the country.
Paul Behrens, a senior author on the work, adds: ‘There will be a rapid increase in the number of electric vehicles on the road over the coming decades, resulting in huge potential for energy storage that can help supercharge the clean grid technologies. If we don’t use these batteries, we would have to build additional “stationary” batteries to help store energy, resulting in even more materials and more reliance on fragile supply chains.’
Coordination is urgent
However, harnessing this opportunity will be challenging. Electric vehicle owners need to have the right equipment, plug their cars in, and be signed up to an energy plan which lets them take part in the energy market as a provider. They can then make money by taking power from the grid at strategic times and giving it back to the grid when needed. However, as lead author Chengjian Xu points out: ‘We know these technologies can provide energy security, but there is not enough coordination across government, technology providers, car manufacturers and the electricity grid to harness this opportunity.’
There are many issues with common charging standards and technologies, and many cars don’t yet come with the hardware needed to enable this powering of the grid. Senior author Arnold Tukker adds: ‘We face a real danger that as electric vehicles outsell their petrol competitors over the coming years, millions of vehicles won’t have the required equipment to harness this storage potential, leading to costly retrofits or lower participation rates.’”