Figure 1. Electrolysers from H-TEC SYSTEMS at a wind farm in Northern Germany. Image courtesy of H-TEC SYSTEMS.
that meets industrial standards (tap water) is necessary as a feedstock for electrolysis. In arid areas, additional water generation may be necessary e.g., with desalination plants.
Synthetic natural gas production by methanation Methanation, or the Sabatier process, is a chemical reaction in which carbon dioxide Figure 2. On the left, hydrogen use by production type, and on the right, hydrogen use by is converted into synthetic methane. It is an region. Source: BP Energy Economics 2020. exothermic reaction that has to be accelerated by nickel catalysts. The chemical efficiency is approximately 83%. From 1 kg of H2, approximately 2 kg of SNG and 4.5 kg of water are produced with the addition of CO2. This is a chemical reaction that takes place without additional energy in the form of electricity. The equipment associated with the methanation reactor, such as pumps, requires electricity, so a total of approximately 27.3 kWh is required to produce 1 kg of SNG. The reactor is a boiling water reactor in which process temperatures range from 270˚C - 600˚C. The process by-products are water and saturated steam at a temperature of 270˚C. If this is integrated into other production processes, the methanation process can achieve an overall efficiency of 95%. The outlet pressure is 20 bar(g). Two reaction stages are necessary for high methane Figure 3. PEM electrolyser by H-TEC SYSTEMS. Image courtesy of purity (>95%) in MAN methanation technology. This is due to H-TEC SYSTEMS. the thermodynamic equilibrium that occurs between the two
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ENERGY GLOBAL SUMMER 2022
