Methane Production via High Temperature Steam Electrolyser from Renewable Wind Energy: A German Study

The transformation of the energy supply needs further development of energy storage technologies in order to integrate the fluctuating renewable energy. The conversion of renewable wind power into green methane offers a technical approach with the necessary storage and transport capacities. Thus, the concept of Power-to-Gas which is illustrated here by the coupling of wind energy with a High Temperature Steam Electrolyser (HTSE) and a methanation unit enabling the production of green fuel like hydrogen and methane is presented is this paper. In fact, hydrogen can be used as energy carrier as well for the production of green fuels, like methane which is simpler to store and to transport and which can be thus used as storage medium for the stabilization of the electrical power supply as well as fuel for transport and heat sector. Its production using high temperature electrolysis is able to reduce the carbon dioxide emissions if performed with renewable resources. This is the case if the electricity needed for the HTSE comes from a wind turbine and the CO2 needed for the methanation step comes from biogas. For such a plant, the location and the boundary conditions have a great importance. Thus, this study considers the coupling of a HTSE with a wind turbine and a methanation reactor, and focuses about the site selection, depending of the geographical and economic considerations. The study is limited first to the European area. Schleswig-Holstein is found as a very good location for this plant. It is one of the regions with the largest wind reserves in Germany. This region has also available a lot of biogas and meets all the other necessary requirements.

Coupling of Wind Energy and Biogas with a High Temperature Steam Electrolyser for Hydrogen and Methane Production

The production of environment friendly green fuels is based on energy from renewable sources. Among the renewable sources, wind power is a very growing power technology. An example which has been discussed very widely is hydrogen which is an ideal fuel for a fuel cell. Hydrogen is the energy of the future. It will be used as energy carrier as well as reactant to produce green fuels, like methane which is easier to handle. Direct coupling of a High Temperature Steam Electrolyser (HTSE) with a wind turbine can be used to generate hydrogen. Indeed performing the electrolysis process at high temperatures offers the advantage of achieving higher efficiencies compared to the conventional water electrolysis. The hydrogen produced can be then reacted with the CO2 content of biogas to form methane as green fuel. Thus, the concept presented in this paper illustrates the potential of the HTSE technology coupled with a wind turbine, this system being combined with biogas in a methanation unit. Developing scenarios and flow sheets and using mass and energy balance, the technical performance of the concept is investigated. A plant capacity of 10 MWel is considered. An annual production of 1104 metric tons per year (Mt/a) hydrogen and thus of 5888 Mt/a methane is reached. The overall plant efficiency is calculated to be 38%. The combination of wind power and biogas offers thus many advantages which can facilitate the penetration of the wind resource and the progression to the hydrogen economy.