Blending Hydrogen With Natural Gas/Biomethane and Transportation in Existing Gas Networks.

The existing European Union (EU) natural gas network provides large capacity to integrate renewable (RGs) and low-carbon gases. Today, hydrogen contributes only a few percent to Europe's energy consumption and is almost exclusively produced from fossil fuels and used in the industry. Nevertheless, hydrogen has a significant role to play in emission reduction in hard-to-decarbonize sectors, in particular, as a fuel in transport applications and as a fuel or feedstock in certain industrial processes (steel, refining or chemical industries, the production of "green fertilizers"). Carbon dioxide (CO₂) in reaction with hydrogen can also be further processed into synthetic fuels, such as synthetic kerosene in aviation. In addition, hydrogen brings other environmental co-benefits when used as fuel, such as the lack of air pollutant emissions. However, in transitional phase from fossil to RG, namely, renewable or green hydrogen, natural gas/biomethane and hydrogen blends, are needed to gradually replace natural in existing gas transmission and distribution networks. The gas networks are believed to be able to use natural gas/biomethane and hydrogen blends with 5–20 % of hydrogen by volume. Most systems and applications are able to handle it without a need for major infrastructure upgrades or end-use appliance retrofits or replacements. The promotion of hydrogen network such as European Hydrogen backbone (EHB) is gaining momentum in Europe. To decarbonize the natural gas grids, the threshold of hydrogen in the existing grid systems must be increased, which can be done by means of wider natural gas/biomethane and hydrogen blending and simultaneous transportation in currently operational gas networks. [ABSTRACT FROM AUTHOR]