Electric cars are increasingly being charged ‘smartly’: they are charged at times of high grid availability and low electricity prices, preventing grid overload and offering cheaper charging. To maximise these benefits, charging speeds should be reduced at busy or expensive hours, and it should also be able to be paused.
Researchers from Utrecht University and TU Delft have shown that adding charging pauses doubles the effectiveness of smart charging. Most cars already support this, but some vehicle models cannot properly handle these pauses. Therefore, the researchers call upon car manufacturers to ensure that all models can handle charge pauses. Standards already exist, but they 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). In this case, cars are not charged when electricity prices are high. 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 vehicles (EVs) can play in balancing the power grid can be twice as big when paused charging is possible. And the user does not notice the pausing: the car is still fully charged at departure.
Smart charging, a 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 of the power grid. In addition, several parties offer smart charging services for private EV owners, allowing them to charge more cheaply or sustainably at home. Smart charging may become the new standard.
Minimum charging speed
Smart charging often still involves a minimum charging rate of 4 kilowatts. Through this, all EV models can cope 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 ‘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
Figures
Figure 1 – Overview of charging costs in different countries for traditional charging, smart charging without charging pauses, and smart charging with charging pauses.
Figure 2 – The number of charging stations that can be installed in a specific electricity grid before grid congestion occurs when considering different charging strategies. In this analysis, smart charging is used specifically to prevent grid congestion.