Smart charging: Turning electric vehicles into power plants on wheels

06 July 2020 - Published by Sophie Rabasch

We spoke with The Mobility House's Jan Winkler about the unique energy storage system using second-life batteries in the Johan Cruijff Arena (JCA). Made from 148 Nissan LEAF batteries, the multi-use storage system enables a more sustainable and secure energy supply by balancing local generation and demand but also supporting the electricity grid. 


The application of end-of-life electric vehicles’ (EVs) batteries as stationary storage has a huge potential for improving EV circularity. However, their repurposing process is not without its challenges. How did you overcome such technical and economic barriers? 

Jan Winkler: The technical system design was done by Eaton. They dismantled the Nissan Leaf battery packs, tested them on cell level and stacked them into new packages. Eaton did a great job in designing this system, so for us – as the system operator – there was no downside to using second-life batteries instead of new ones. Of course, the topic of degradation often comes up when speaking about second-life batteries. So far, we did not experience any unusual degradation and the system has now been in operation 24/7 for nearly two years! 


We have experience with EV battery-based storage and are currently operating nearly 30 MW of second life energy storage systems in Germany. Economically, the advantage is still limited. A second-life battery system comes at similar, sometimes even higher prices than newly manufactured batteries. The ambition for us and the ArenA, however, was not to create the best business case but to use batteries that have already reached the end of their emissions lifecycle and implement a low-waste solution which shows the potential of a circular economy. Hopefully, acting sustainably will soon also be awarded economically.


What are the impacts in terms of CO2 emissions avoided and costs?

JW: We had a third party calculate the reduction in emissions. Over its whole lifetime, our battery storage will have saved a total of 116 000 tons of CO2. Cost savings are a bit more challenging to assess. The costs for the battery were distinctly higher than those of a diesel generator, which would have been the alternative backup device for the ArenA. However, diesel generators are only of use in the event of a blackout. The battery creates value every single day. During events, it is a backup power resource and can help reduce the maximum grid load. During non-event days, we operate the system on the frequency control market and help balance the Dutch transmission grid. This service is compensated by Tennet and we can generate revenues of anywhere between €500 and 2000 a day to earn back a part of the investment costs.


Today, visitors to the JCA can actively contribute to the arena’s power supply if they’ve come by electric car. The car can be integrated into the stadium’s own power grid using software that not only charges the cars but actually also feeds electricity back into the stadium’s electrical infrastructure. Vehicle-to-Grid (V2G) feels like an important development in energy supply innovation. Can you tell us more about the challenges when it comes to implementation?

JW: We have been involved in several R&D projects in the field of V2G over the last years. The technology is well-established and has proven its benefits in providing grid services such as frequency & voltage control and redispatch. It is also a great solution for private EV owners who have a photovoltaic system installed on their rooftops and are looking for a way to increase their local green energy consumption. The biggest obstacle right now is that only very few car manufacturers have implemented bidirectional charging in their electric cars. Currently, Nissan and Mitsubishi are, as far as I know, the only manufacturers that offer such cars. Others – like Renault – are experimenting with the technology and use specially customised cars in pilot projects. It will take a few more years before V2G technology will have its breakthrough. We are waiting impatiently for this to happen and use the time to optimise our smart charging system, ChargePilot, which we use to connect electric cars to buildings and the energy grid. 


The ChargePilot is designed as an open system using standardised interfaces and protocols. What are the benefits of building an open platform?

JW: We believe that the customer – in consultation with his installer – should be free to choose what system components he wants to have installed. This is true today when he starts with a first installation of say 5-10 chargers but also and even more in the future when he might want to ramp up to 50+ chargers. Today, several hardware manufacturers offer smart charging software with their products. In most cases, these are closed systems with proprietary interfaces that only they know. This leads the customer into a lock-in situation. If the customer wants to eventually add a different brand or technology, this will be nearly impossible. Seeing that the EV market is still at a very early development stage, I do not think anyone can decide today which hardware he will want to use in one, three or five years. This is why we are strongly advocating open standards. Our charging and energy management system communicates to the chargers via the OCPP protocol (currently OCPP1.6, in future: OCPP2.0), as defined by the Open Charge Alliance (OCA). This makes it possible to integrate any charger brand and technology (AC, DC, high/low power, V2G, …) if they have implemented the proper protocol. This way the customer keeps their freedom to combine technology in the way that they choose.


Amsterdam is actually aiming to become the V2G capital of Europe – what is/should be the next step for the city after the JCA?

JW: Amsterdam is really setting the path for V2G and electrification of traffic in general. By 2030 any vehicle that drives within the greater Amsterdam area (including the area around the Johan Cruijff ArenA) will have to be a zero-emission vehicle. As for V2G, several interesting projects have been implemented, including the one we did at the ArenA and the Flexpower project which was also supported by Interreg North Sea Region. I am sure, more projects will be realised in the near future. 


For me, the most important thing now is to demonstrate how V2G can be implemented on a larger scale and in everyday use. This should cover public parking but also company fleets and special venues such as airports where people park their car for longer. I would also like to see V2G with canal boats at some point. By 2025, all passenger boats on Amsterdam canals will have to be electric. This creates a huge potential for smart charging and vehicle-to-grid – in case it will be considered by the engineers, designing the boats and chargers.


How does the Mobility House see the trend of smart charging growing in the coming years? Is it going to be a city-led effort?

JW: Our company vision is to create maximum value from EV batteries by connecting it smartly to the energy ecosystem. This vision materialises in subsequent steps. Right now, the focus is on enabling EV charging by implementing dynamic load balancing. This way, customers can install up to twice the amount of chargers behind a given grid connection and/or save significant costs (avoided costs for grid extension, cabling, transformers, switchboards and annual grid & demand fees for peak load). In most projects, these cost savings exceed the costs of our system by a factor of 5-10 or even more. 


The logical next step is integrating the chargers into a local smart grid, by connecting our controller to the local energy management system. Once we have aggregated several chargers in a customer site, we will connect the installation to the local distribution grid and provide grid services. Shifting charging power from a period of high grid load to an off-peak time supports the grid quality and helps avoid infrastructure investments. This will be compensated by the grid operator with a discount on the grid fees, the customer needs to pay. We are doing this right now in a demonstration project with the local grid operator in Hamburg. 


Lastly, we want to allow our customers to benefit from the price fluctuations on the energy wholesale markets. Put simply: whenever a lot of renewable power is produced and market prices are low (sometimes even below €0), we will charge all EVs at our customer’s site at a much lower rate than they would normally pay. Once all the pieces of the puzzle are in place, the full value of smart charging can be unlocked within a very short period. And it can all be done before V2G is even a relevant factor and provides even more potential to create value from EV batteries. I think this development will be driven by customer demand and it is our job to educate and showcase the value that lies in an EV during the 95% of time it is parked and not used for driving.


As The Mobility House and their partners demonstrated in the Jan Cruijff ArenA, exploring innovative business models and applications allows us to unlock the full potential of future opportunities. There is a lot we can take away for the development of our own ambitious pilots in the ACCESS project.