Turning Excess Wind Power  

into Green Gas


Hydrogen produced from excess wind power converts biogas from wastewater slurry into green natural gas. New Danish energy venture for approx. EUR 13.4 million shows how to integrate the energy system of the future.

Wind Turbine

Wastewater slurry and excess wind power can now be converted into green natural gas thanks to the Danish project 'Power-to-Gas BioCat2'. The project has received EUR 3.7 million from the research fund ForskEL, and, together with a sister project at Avedøre Wastewater Services, an international-scale demonstration plant will now be established. The two projects will demonstrate how biogas and electricity can be turned into methane:

- "Now we will finally create the link between Denmark's abundance of wind power and production of eco-friendly gas to the Danish natural gas grid. The integration is a necessary piece of the puzzle to transform the energy systems and phase out coal, oil and natural gas system in the long term," says Kim Behnke, Head of Environment, Research and Development at Energinet.dk.

Storing excess wind as hydrogen and green gas

Wind power in Denmark has reached a level where the total electricity consumption is covered by wind for many hours. In December 2013, 55% of the total Danish electricity consumption came from wind, and for several days, the coverage was more than 130%. However, more green energy sources are needed to ensure a stable supply of electricity and heat when the wind is not blowing. This calls for Danish combined heat and power plants to use gas from green sources.

At the wastewater treatment plant in Avedøre, Electrochaea is now building a 1 MW electrolysis plant, where electricity from wind power and water is converted into hydrogen. Hydrogen is used for upgrading biogas before it is injected into the natural gas grid.

International-scale demonstration plant

The wastewater treatment plant produces biogas from decomposition of wastewater slurry. In addition to methane, biogas also contains CO2, and therefore it cannot be sent to the Danish gas customers through the natural gas grid. However, a new biological process is able to upgrade the biogas.

At the same time, the sister project is testing a new technology for chemical upgrading of biogas. Excess CO2 from this process can also be converted into methane in the P2G BioCat project.

- "Together, the two projects will make one interconnected, international-scale demonstration plant, and it will deliver qualified suggestions to the P2G solutions of the future," says Kim Behnke, Energinet.dk.

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