Problems of the Hydrogen Economy

There is a problem with a transition from natural gas (methane) to hydrogen for domestic use, if such a transition is deemed necessary. The pipelines that carry natural gas could carry a mixture of methane and hydrogen or just hydrogen but hydrogen has a destructive effect on many metal pipes due to embrittlement. Although H2 also leaks from plastic pipes at a greater rate than methane, its rapid oxidation to water vapour makes it less of an overall problem. The key concern is that due to the lower energy values of gaseous H2 than methane, H2 has to be pumped at a higher rate/ pressure, which makes it incompatible with domestic methane consuming equipement. H2 will burn but the risk of blow-back increases, which can damage equipment. Also, like methane, H2 is odourless so in principle an artificial odour could be added (as is currently done for methane). However, such H2 is then no longer as usable for fuel-cells which become contaminated by such impurities.

A potentially devastating problem is the use of rare materials for catalysis in electrolysers and fuel-cells. Less effective but more available materials such as nickel are being used but the lower the efficiencies, the more energy is required at every stage. However, these problems are being worked on and other than contamination, the catalysts should always be recoverable.