Chapter 4: Hydrogen

Methods for manufacture of hydrogen are described, in particular steam reforming. The use of town gas before the discovery of North Sea oil and gas is described, as are heat pumps that may replace gas central heating to mitigate the effect of global warming. Magnetic refrigerators based on the use of magnetocaloric materials are described. Supply chains and geopolitical issues related to hydrogen are highlighted, e.g., the war between Russia and Ukraine curtailed exports of natural gas from Russia to countries that had relied on them. Fracking and shale gas are outlined. A major use for hydrogen is in the Haber–Bosch process for ammonia manufacture. This process requires large static plant. A brief discussion is given of ammonia synthesis by mimicking how ammonia is made in biological systems. For example, reduction of nitrogen to ammonia in the presence of nitrogenase enzymes by use of electrocatalysis. The release of a greenhouse gas, nitrous oxide, from artificial fertilisers based on ammonia is covered. The hydrogen economy is outlined, as is the use of hydrogen as a fuel. Nuclear fusion and types of fusion reactors are briefly described.