Power to Gas: Efficient power storage technology in the Münsterland region

Power to gas technology is a central component of the transformation of the energy system. In the case of excess electricity, for example during high wind activity, water can be split into hydrogen and oxygen using an electrolyser. In contrast to electricity, hydrogen can be easily stored. RWE engineers have now developed a particularly efficient variant of this power storage technology, which is being used for the first time in the Münsterland region.

Generating electricity using renewable energies has one disadvantage: it produces power even when it is not needed. In order to be able to also use this surplus, storage solutions need to be developed.

Engine for progress:

  • overall efficiency of 86 per cent through the use of waste heat
  • development of a process gas chromatograph to precisely determine the calorific value
  • use of 100 per cent green electricity from wind energy
  • supplying 40 to 50 households with heating energy from waste heat

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Foto: RWE

The centrepiece of the plant is the 150 kW electrolyser based on PEM (proton exchange membrane) technology.

Hydrogen from water and electricity

The energy landscape in Ibbenbüren offers the ideal conditions for demonstrating an innovative storage solution: Through multiple links between the local electricity, gas and district heating networks, a system solution has been developed there, which shows how excess electricity from renewable production can be saved on a very large scale without having to tolerate disproportionately high energy losses while doing so. "First of all, hydrogen is produced from the surplus electricity by electrolysis," explains Ulrich Bohn, head of the project at RWE Deutschland AG. "This hydrogen is introduced into the natural gas network to a controlled extent.”

The hydrogen fed into the network would lead to an energy surplus there. Therefore, these exact energy quantities are extracted from the network at the same time to another point in the form of natural gas and stored at a natural gas storage facility. If, at a later point in time, insufficient sun and wind are available to generate electricity , these quantities of gas are extracted again and used to generate electricity at a combined heat and power (CHP) plant on the Ibbenbüren district heating network. In the future, RWE also hopes to use the resulting hydrogen for mobility or heating applications.

The most efficient plant in Germany through the use of waste heat

What is special about the RWE solution is that the electrolysis does not release excess heat into the immediate surroundings. Instead, a neighbouring gas-pressure regulator station uses the waste heat for process purposes. This prevents losses and makes the system the most efficient power to gas system in Germany. And the re-conversion procedure from gas back into electricity is just as efficient. The CHP plant used to do this not only feeds power into the public network, it also feeds the resulting waste heat into the Ibbenbüren district heating network.

Photo: innogy

"The power to gas technology represents the perfect link between the electricity and gas grids. It ensures that excess electricity from renewable energy sources is not wasted but rather stored as gas. Thus power to gas can become a key building block for our future energy supply."

Dr. Armin Gaul, Head of Supply Concepts and Tools in the Area of Network Strategy, RWE Deutschland

Partners and sponsors

  • RWE Deutschland AG