Making smart charging of electric vehicles even smarter

Electric cars are increasingly being charged 'smartly', which means they are only charged at times of high grid availability and low electricity prices. Smart charging prevents grid overload and saves you money. To get maximum benefit from smart charging, you not only want to reduce the charging speed at busy or expensive hours, but also be able to pause charging. Researchers from Utrecht University and TU Delft show that adding charging pauses doubles the effectiveness of smart charging. Most cars already support this, but some car models cannot handle these charging pauses properly. The researchers call on car manufacturers to ensure that all models can handle charge pauses. The standards for this already exist, but are sometimes not appropriately applied. Making technical smart-charging requirements mandatory could help.

The researchers calculated that the cost benefit of smart charging over traditional charging is about twice as great when paused charging is possible (Figure 1). After all, cars are not charged when electricity prices are high. Also, paused charging alleviates grid congestion, making room for twice as many charging stations compared to smart charging without pauses (Figure 2). Furthermore, the study shows that the role electric cars can play in balancing the power grid can be twice as large when paused charging is possible. And the user does not notice any of this: the car is still fully charged at departure.

Smart charging as the new standard

Smart charging has already been applied on a large scale at public charging stations in several major cities, including Amsterdam, Rotterdam and Utrecht in recent years. More and more municipalities, when installing new public charging stations, are requiring the implementation of grid-conscious charging, which is a form of smart charging that takes into account congestion on the power grid. In addition, several parties offer smart charging services for private electric car owners, allowing them to charge more cheaply or sustainably at home. This indicates that smart charging seems to become the new standard.

Minimum charging speed

Smart charging now often still involves a minimum charging rate of 4 kilowatts. In this way, all electric car models can cope well with smart charging. However, this minimum charging rate is relatively high as it corresponds to the average peak demand of about two households, even at unfavorable times. Charging pauses are not yet commonly used because some, especially older, car models then 'fall asleep' and cannot resume charging afterwards. Therefore, in many cases, a minimum charging rate is now used with smart charging, even for car models that can handle charging pauses. The implementation of paused charging was tested in Utrecht, at charging stations from project partner We Drive Solar.

Solution

Efforts are currently underway to implement an improved communication protocol that takes charge pauses into account, and more and more car manufacturers are ensuring that their car models can properly handle these charge pauses. However, it is currently not a requirement that electric cars must be able to cope with lower charging speeds or charging pauses. Once electric cars can do so, smart charging will be even more effective in maintaining grid stability and reducing charging costs.

Partnership

This research follows from the ROBUST and SCALE research projects, in which various research institutes, companies and governments are jointly researching the smart charging system of the future. The ROBUST project is co-funded by TKI Urban Energy, the Ministry of Economic Affairs and Climate and the Ministry of the Interior and Kingdom Relations. ROBUST falls under the central government's Mission-Driven Research, Development and Innovation (MOOI) scheme. SCALE is funded by the European Union's Horizon Europe research and innovation program under grant agreement No 101056874.

Publication

Nico Brinkel, Thijs van Wijk, Anoeska Buijze et al., ‘Enhancing smart charging in electric vehicles by addressing paused and delayed charging problems’, 2024, Nature Communications, https://doi.org/10.1038/s41467-024-48477-w