Decarbonisation Technology - February 2023

The conditions for the initiative are unique, especially on the west coast of Schleswig- Holstein, a region with strong wind energy and excellent geological storage conditions and home to innovative companies. These storage conditions are a special feature of the Westküste 100 project. There are a number of underground caverns close to Raffinerie Heide. Salt caverns appear in the form of underground cavities as a result of a leaching process. Deep drilling is used to reach underground salt domes, which are extracted by adding water in controlled conditions and will be used to store green hydrogen. The aim is to convert the available but intermittent renewable energy sources (RES) into a continuous supply of energy for industrial use. Green hydrogen will be available even in times of ‘dark doldrums’. Westküste 100 real-world laboratory Once the electrolyser is operational with the subsequent use of green hydrogen, the real- world laboratory project will obtain fundamental economic, technological, and scientific findings. This will provide sound knowledge on the energy and material cycles, as well as their feasibility, necessary for future scaling up of the project. Cross-sector closed value-creation chains in the region should emerge in this way. The electrolyser will be integrated into the existing refinery process to demonstrate the production and direct industrial use of hydrogen. A cavern storage system nearby will be re-purposed as interim storage for

the hydrogen generated and, if required, provide it for industrial use. A hydrogen grid between the refinery, the cavern, and Heide Municipal Utilities (called Stadtwerke Heide) will be created in parallel. Innovative pipeline technology in the grid section between Raffinerie Heide and Heide Municipal Utilities will be put into operation for the first time. In this phase of the project, the partners will investigate how hydrogen can be integrated into the existing gas infrastructure in the long term. The admixing of green hydrogen in one section of an existing gas grid will enable the decarbonisation of the gas supply for heating. Two feasibility studies will also examine how the oxygen, co-produced via electrolysis, can be fed by a so-called ‘oxyfuel process’ into the firing process of the cement works in Lägerdorf and the carbon dioxide (CO 2 ) subsequently separated off. The CO 2 from the cement works and the hydrogen from the electrolyser may be used as feedstocks to a plant for the synthesis of methyl alcohol in the future. Following this, the exhaust gas can be treated to give high-purity CO 2 for use as a feedstock for the chemical industry and other business sectors. The studies provide fundamental data on the technical and economic feasibility of downstream CO 2 extraction and treatment for methanol synthesis. The methyl alcohol synthesis process can, in a step downstream from the Westküste 100 project, be a basis for producing synthetic fuels, such as aviation fuel. In addition, recovery and use of waste heat from the electrolysis