A new-build project in Esslingen aims to show that a climate-neutral district energy supply is possible. That is why an electrolyzer that converts solar power into hydrogen is being installed in the district. This hydrogen could even be used in future to fuel the residents’ cars.
A climate-neutral district is currently being built in Neue Weststadt, Esslingen that could act as a blueprint for future district development projects. Over 500 apartments, office spaces, and commercial sites have been built across an area of 100,000 m² over three years, as well as the newly constructed Esslingen University of Applied Sciences.
What the district is still missing, however, is its technical heart: This year, an electrolyzer that uses the solar power from the roofs to produce green hydrogen is to be installed in an underground power station. To this end, the electricity provider Polarstern, Professor Manfred Norbert Fisch (from the Steinbeis Innovation Center EGS in Stuttgart), and the Esslingen municipal utilities have established the company Green Hydrogen Esslingen GmbH, which is now implementing the power-to-gas solution in the district with funding from the Federal Ministry for Economic Affairs and Energy (BMWi).
“With this concept, we have brought electrolysis to the city,” explains Tobias Nusser of the Steinbeis Innovation Center EGS. “There are already a few facilities operating around one megawatt in Germany, but they are all out in the countryside, so they may well be near the energy producers, but generally they are far removed from the cities where the energy is in demand.”
Situating the plant in the district has two benefits: Transport routes for using the green hydrogen are shortened and the waste heat from the electrolysis process can be used for supplying heat to neighbouring buildings. The participants in the project hope that this will help to increase the utilization of electrolyzers from about 60 %, as it normally is, to up to 90 %.
“To this end, the building technology is being oriented towards this heat source and we are using a low-temperature system, thus replacing fossil fuels such as natural gas,” explains Nusser. The effect should also be magnified by the fact that while the waste heat is used to heat the district itself, other Esslingen residents can also use the green hydrogen, since it will also be fed into the gas network, reducing the proportion of natural gas there.
Hydrogen subsidy for funding hydrogen feed-in into gas network
The municipal utilities are currently working on a business model for this, since natural gas is still much cheaper than green hydrogen. “This could be offset by some kind of hydrogen subsidy for funding climate-friendly gas,” says Nusser. Assuming a gas price of 6.15 cents per kilowatt-hour, this subsidy could be set at around 0.05 cents. For a typical family, this would mean less than a euro per month in additional expenses.
There are also other possible uses for the 400 kilograms of hydrogen that the electrolyzer is expected to produce every day. Over the course of a day a filling station could fill the tube bundle of a trailer, which then takes the hydrogen to industrial customers. There is also the idea for a filling station for fuel cell vehicles. However, there will not be a large store of hydrogen in Esslingen, so as to save Green Hydrogen Esslingen the expense of construction and the associated approval process. 30 kilograms will be sufficient, since the hydrogen is expected to be removed immediately.
However, the project partners have to agree the plan first. Approval according to the Federal Immission Control Act (BImSchG) including public participation is expected to be granted at the beginning of April. Professor Fisch’s engineer’s office EGS-Plan is currently devising the plan for the power station as well as the supply and plant technology, with construction of the electrolyzer set to begin in April. The first supply of green hydrogen is expected by the end of the year.
“But our method of operation will also be based on the availability of renewable energy sources, another important aspect of the project,” explains Nusser. He envisages around 4,000–5,000 hours of operating time per year – with hydrogen being produced around 50 % of the time. The electrolyzer might be able to constantly pull electricity from the grid, but part of the research project is to trial the approach of using surplus electricity from the grid to contribute to the energy transition.
Project also integrates local public transport
The project as a whole is known as the Es_West_P2G2P project and has been running since 2017. The concept is based on a cost-optimized reduction of the electricity, heating, and cooling demand of the buildings (mixture of residential, commercial, services, and university) with extensive use of renewable energy.
The first tenants moved into the residential building on the former premises of Esslingen am Neckar’s goods depot in 2019. They share the electricity generated in the district with the local public transport network, as another part of the project is to use surplus power in the grid to charge batteries in trolleybuses.
“And when all is said and done, we don’t want to leave things just at this project,” says Nusser. “Green hydrogen can help to establish a local energy economy and increase regional value creation, and the solutions we have developed for using green hydrogen are definitely transferable.”