The role of electric vehicles in Positive Energy Districts

The role of electric transport in Positive Energy Districts

Although most of the mobility energy use does not take place within the district one lives in or works, it would be false to ignore its energy use. Refuelling of gasoline vehicles does often take place within this neighbourhood. With the rise of electric vehicles, this will be even more common, as most charging of these vehicles takes place at home or at the workplace [1]. With electrification, transport also becomes a part of the local energy grid, even more reason to include energy use from vehicles in the energy balance of a district. Electrification of passenger and commercial vehicles is about to lift off in the years to come as they are also one of the most striking proposals in the new EU Fit for 55 package [2]. By 2035, all newly sold vehicles must be zero-emission. Not taking this into account in newly built districts would be an ignorant move concerning the recent future.

Including the energy need from mobility would significantly increase the challenge to make a district energy positive. To compare, the energy needed to propel an electric vehicle for about 15.000 km a year (Dutch average) is about the same to the electricity consumption of a two-person household. If all household would have a vehicle, this would double the energy demand. This would also require a significant increase in the energy production within the district.

Balancing the energy grid

Including mobility demand not only brings an additional load to the district, but it also provides a large opportunity. Electric vehicles are basically batteries on wheels. Using these batteries, use of locally produced renewable energy can be optimised and reduce the need for local energy storage to increase self-consumption of this energy. This can be done by integrating the charging of electric vehicles within the Energy Management System of the building and using a so-called technique: Smart Charging.

Using smart charging, electric vehicles are charged when there is sufficient energy from locally produced electricity. Electric vehicles are charged when they are parked, this is over 23 hours per day on average. This provided ample room to spread the energy need of these vehicles throughout the day. This allows the energy demand of these vehicles to be fulfilled when there is an energy surplus in for example a sunny day.

Going beyond

Besides balancing the energy grid and increasing self-consumption electric vehicles can also deliver electricity to the local grid by using Vehicle-2-Grid Technology. Using this technology, electric vehicles not only charge when there is a surplus, but also discharge when the demand exceeds the local production. In this case energy produced during the day from solar panels can be used in peak demand around 6 pm when electricity use is highest due to cooking and heating demand.

Recent Amsterdam University of Applied Sciences graduate Rinke de Zwart [3] investigated the potential of this technology for the Republica Building to be built in the Buiksloterham district in Amsterdam. Using real data from electric vehicles on the road and combining these with energy profiles from the building has allowed him to gain insight in how electric vehicles with vehicle-2-grid can support the local energy grid and increase self-consumption. He simulated different scenarios for the future in which the uptake of electric vehicles has increased significantly. Additionally, a local battery was included in the scenarios to see if that would enhance self-consumption.

His results show that if all inhabitants of the building would have an electric vehicle, this would reduce peak power consumption by 40% and self-consumption by at 30%, from 60% to nearly 90%. Including a stationary battery would even give the possibility to reduce peak power consumption by 80% and increase self-consumption up to 95%. This would mean that the building almost can function without a connection to the external electricity grid and thus operate almost fully on locally produced renewable energy. As peak power consumption decreases a smaller grid connection would be needed, from 350kW down to below 50kW, which could also provide significant cost savings.

Conclusions

This blog has made a clear case for why energy use from mobility should be included in the definition of a PED. Not only would leaving out mobility exclude a large source of energy use without a specific reason, with the advance of electric mobility it also becomes increasingly integrated with the local energy grid and can therefore no longer be ignored. Although the additional energy use from electric vehicles is significant, they also provide great opportunities when integrated in local energy management systems.

Use of technologies such as smart charging and vehicle-2-grid have great potential to increase self—consumption and thus decrease reliance on fossil fuel produced electricity from the grid. Results from a case study in Amsterdam shows that Vehicle-2-Grid combined with a stationary battery increases self-consumption, and lowers CO₂ emissions. It also reduced peak power demand which in term means lower grid connection costs. This also benefits grid operators which already feel the strain of the energy transition on their grid.

Author: Rick Wolbertus

Picture Credits: Unsplash

[1] https://www.sciencedirect.com/science/article/pii/S2210670721002973

[2] https://www.eia.gov/totalenergy/data/monthly/pdf/sec2.pdf

[3] https://www.mdpi.com/2032-6653/11/4/73/pdf

[4] https://www.europarl.europa.eu/legislative-train/theme-a-european-green-deal/package-fit-for-55

[5] Scriptie