The changes introduced by the ongoing energy transition represent a major challenge for energy systems. In particular, maintaining the necessary balance between electricity production and consumption will become an ever more demanding task for grid operators due to the increasing share of renewable energies. Switzerland is no exception in this respect, as a significant portion of today's electricity is generated in nuclear power plants that will be decommissioned in the midterm and are envisioned to be mainly replaced by renewable energy sources. One approach to solving this problem is to use the rapidly growing battery capacity of electric cars. When these are connected to the grid - for example when they are being charged - their batteries could be used to store excess energy from the grid and quickly feed it back into the system when needed. Yet, it is not clear how this potential could impact the need for energy imports in Switzerland. In a study researchers from the NCCR Automation have investigated just that.
"Our main goal is to reduce electricity imports from neighboring countries. These are often generated from greenhouse gas (GHG)-intensive energy sources, like coal and gas, emits very little greenhouse gas. Instead of exporting our surpluses of energy production, we should therefore try to keep them inland," explains Loris Di Natale, lead author of the study and doctoral candidate at Empa. "Therefore, we investigated how we can control the charging and discharging of the batteries of electric vehicles (EVs) to decrease the amount of necessary electricity exchanged with neighboring countries. If grid operators have the ability to shift the charging and discharging of EVs to different times of the day, such as charging midday when there is a lot of solar energy available and discharging at night when there is significantly less renewable energy production, imports can be significantly reduced," Di Natale says.
If this technology is combined with other storage technologies, such as dams and pumped hydro storage power plants, the researchers estimate that the imports can be reduced by up to 60% by the year 2050. This is achievable not least since the two technologies complement each other: electric cars absorb the daily fluctuations while hydro-based power plants are used for longer-term storage. Yet even if these results are very promising, the potential of EVs is not limitless, as Di Natale points out: "Remarkably, we found that the potential of EV batteries is exhausted beyond a certain number of cars. This means that we cannot expect electric cars to completely solve our storage problem. Especially for seasonal storage, we have to additionally look for other solutions."