Generating electricity and heat from water in an environmentally friendly way – that is technically possible.
Experts are convinced that hydrogen could also play an important role in the building sector in the future. But the price is still very high.
How can energy from renewable sources be used flexibly in terms of time and space? Satisfactory answers to this question are still being sought in the context of the energy and heat transition. Environmentally friendly electricity can be stored in batteries. However, they are expensive, have limited capacities and are problematic to dispose of. In addition, they only make a limited contribution to the heat supply, for example by providing electricity to operate heat pumps.
Experts are therefore placing great hope in another technology: “The use of hydrogen will play a decisive role alongside renewable electricity, climate-neutral district heating and the composition of the gas mix from CO₂-neutral gases,” says Axel Gedaschko, President of the German Housing Association GdW. Although this is still a pipe dream in the building sector, initial projects show the potential of hydrogen.
Climate-neutral district – also thanks to hydrogen
In Esslingen, for example, a climate-neutral neighborhood has been created that produces enough electricity and heat to supply all residents. Hydrogen is an important component. Around 400 kilograms of the gas are produced every day by electrolysis. The chemical process requires water and energy, which comes from photovoltaic, wind power and biogas plants. The hydrogen is stored or fed into the natural gas grid, explains Tobias Nusser from the Steinbeis Innovation Center energieplus.
Electrolysis produces waste heat that can be used for heating. “In this way, we manage to raise the efficiency in this water electrolysis process from around 60 percent to up to 90 percent,” says Nusser. The hydrogen can also be used to operate a combined heat and power plant with a fuel cell that generates electricity and heat. In so-called “cold combustion,” electrolysis is reversed, so to speak: Hydrogen and oxygen then react to form water.
Suitable for suburban housing developments
The complete system is not suitable for single-family homes, but it is suitable for suburban housing developments, explains civil engineer Manfred Norbert Fisch, who is the main driving force behind the project. Sufficient heat could be produced there to supply existing buildings in the city centers. It is even conceivable to operate hydrogen filling stations for trucks.
Plans for an energy-autonomous district with single- and multi-family homes, a daycare center, office building and filling station in Gütersloh are also large-scale. The H2 district is to be supplied with electricity from renewable energies. Surpluses are to be stored in the form of hydrogen. About 368 kilograms of hydrogen per day are needed, which could be produced in three electrolysers. However, the project would not be feasible without government support in the millions, explains investor Dimitrios Tassikas.
Hydrogen for the home
The Picea system from the Berlin-based company Home Power Solutions (HPS) converts electricity from a photovoltaic system, for example, into hydrogen. This is stored in gas cylinders that are located outside the house for safety reasons. In times of low sunlight, the gas is converted back into electricity in a fuel cell, explains press spokesman Nils Boenigk: “In this way, homeowners can make themselves one hundred percent independent of external suppliers.” If a heat pump is operated with the electricity, this also applies to the heat supply.
However, the system comes at a price: according to Boenigk, the smallest variant costs about 85,000 euros, while the largest costs up to 125,000 euros. However, subsidies can be claimed. The KfW Program 433, for example, provides grants of up to 15,500 euros. The technology is suitable for new buildings, says Boenigk.
