The power of many

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by Lotte Lehmbruck / 18 November 2020
Pooled EV batteries to deliver control reserve to the electricity grid

The (electric) engine is running – How to use EVs for grid balancing

After two years of development, in August 2020, Next Kraftwerke and Jedlix started offering secondary reserve power (aFRR) to the Dutch grid using a pool of electric vehicles (EVs). Nick Hubbers, Jedlix, and Elias De Keyser, Next Kraftwerke, talk about their ambitions, how they realized this project, and what they learned along the way on using electric vehicles to balance the grid. Fasten your seat belts and keep reading!

Can you shortly explain how the provision of control energy works with a pool of EVs?
Nick Hubbers: Jedlix has developed a Smart Charging app in which the drivers of electric vehicles specify their charging preferences. Jedlix collects this information and combines it with real-time monitoring of the pool of cars. All this information is used to optimize the charging process and forecast the available flexible power in the hours to come. We pass on this aggregated flexibility forecast to Next Kraftwerke. 

Elias De Keyser: The available flexibility is then offered as aFRR-service to the Dutch transmission system operator TenneT. This means that as soon as major grid fluctuations occur, we stop or start charging the electric cars to counteract a power deficit or surplus. An indispensable aspect of ancillary service provision is to guarantee we are there when the grid operator needs us. We, therefore, built in a safety margin to account for cars that drop out of the pool unexpectedly. By combining the EVs with other flexible technologies like biogas or P2X, the reliability of the total pool increases further. 

Can participating EV-drivers also cancel the charging processes unannounced?
Nick Hubbers: Yes, they can. The driver is not limited in any way in their car usage. If a driver aborts the charging process earlier than initially indicated in the app, we adjust our flexibility offer towards TenneT. Of course, the driver then benefits less from the proceeds of the activation of balancing energy, because he can only provide aFRR if he is connected to a charger.

That makes sense. Can you explain the benefit for the drivers? 
Nick Hubbers: For every kilowatt-hour of smart charging, drivers receive a financial reward. Among other insights, they can monitor their earnings in the app. Once they reach a certain threshold, the rewards are transferred to their bank account. 

How does Tennet monitor your response to their aFRR activations?
Elias De Keyser: For all cars in the pool, we monitor the current power consumption in real-time and the expected power consumption one minute ahead. The latter is known as the baseline. We send this information to TenneT via our secured communication channel. This way, TenneT can observe how much we deviate from our schedule during an aFRR activation and hence evaluate how much aFRR we have delivered.

Providing control reserve through electric vehicles

The graph visualises the response of the pool of electric vehicles to activations by TenneT during a usual night. The sudden drops in the fleet’s total charging activity reflect the interruption of charging by Next Kraftwerke.

Where do you measure the charging power – in the car, or at the charger?
Nick Hubbers: In the car. Modern electric vehicles are equipped with tons of sensors and measuring devices, which allow us to sub-meter the electricity consumption of the car. This is a new approach, which we have developed in the pilot project. It makes delivering aFRR technically independent of the type of charging station. Due to administrative restrictions, today, delivery of aFRR can only take place through the home based chargers. Technically, though, it could already be provided from any charging station in the country. 

Does Tennet accept these metering values instead of the usual DSO or TSO meters?
Elias De Keyser: They do, after a car model has gone through an extensive testing procedure Jedlix and TenneT co-developed during the pilot. The tests took place at the Testlab of ElaadNL, a smart charging innovation center set up by a consortium of Dutch grid operators. Thanks to these tests, we can prove to TenneT that every car responds accurately and in due time to the aFRR activations signals. 

Obviously, there was little ground to build on in this project; most processes had to be built from scratch. Why were you excited to take part in the pilot project?
Elias De Keyser: In terms of grid balancing volume and budget, aFRR is the most important mechanism to maintain the balance in the grid. We are therefore happy that TenneT wanted to investigate how aFRR capacity can be purchased from more diverse sources. By allowing new forms of decentralized flexibility such as EVs, the aFRR market becomes more competitive. The result will be lower social costs for system balancing. A large group of smaller units is also more reliable and has lower CO2 emissions than the large power plants that historically supplied aFRR.

Nick Hubbers: This pilot was an example of how to make a real-world impact and strike the right balance between sandboxing and interacting with real operational systems. Participating allowed us to demonstrate that EVs charging at home can deliver balancing services and be an important asset towards a sustainable electricity supply. 

The Netherlands is often seen as a leader in electric mobility. Could you imagine delivering control power with EVs in the German market too? 
Elias De Keyser: The provision of control energy with mobile assets is somewhat more complex than with stationary assets, especially if they are connected to the low voltage grid. Several questions need to be addressed, such as "in which balancing group is the control energy provided?", “what is the impact on the household supplier?”, and "how can prequalification processes be designed in a way that works for everyone?”. In Germany, these questions need to be clarified first. Projects like the one with Jedlix and TenneT are very valuable because we learn how these questions can be solved best. It also builds confidence among other European grid operators that decentralized flexibility can reliably deliver ancillary services. 

What was your biggest learning from the pilot project? 
Elias De Keyser: We have been delivering aFRR for several years in countries like Germany, but we didn’t have any experience with electric cars. This pilot project was an opportunity to push our boundaries and experiment with the flexibility potential from an EV-fleet. We also developed a unique approach to integrate the EVs in our pool, whereby Jedlix acts as a sub-aggregator. The integration with their systems provides a blueprint for other integrations of fleets of, for example, home energy storage systems and domestic electric boilers. This will come in handy in the near future, for example in our collaboration with Sonnen. 

Nick Hubbers: Obviously, we assumed EV drivers would be willing to provide control energy. Still, it was very reassuring for us to see, that they really are committed. From a technical point of view, we learned that it is challenging but doable to provide aFRR. However, for a sustainable solution and participation in the regular market, there are still some administrative barriers to overcome. We understood that the role of an independent aggregator is new to the established system and still needs to find its place. For now, we are very happy to have achieved our main objective and shown that electric vehicles can deliver aFRR successfully.

Questions asked by Lotte Lehmbruck.

Lotte Lehmbruck is your press contact at Next Kraftwerke.

Lotte Lehmbruck

Head of Communications & Market Research