Dave Elliott: There has been much talk about green gas. It comes in various forms, the most obvious being biogas — biomethane made by the anaerobic digestion of bio-materials, including wastes. But there are also synthetic gases, for example hydrogen made from fossil gas by steam reformation (SMR), backed up by carbon capture and storage to make its production lower carbon. As yet less developed, there is also zero-carbon hydrogen made using renewable electricity, via electrolysis, that can be converted into methane and other synfuels — the so-called “Power to Gas” route (P2G). Whether a green gas grid can or should replace, or just augment, an enhanced power grid transmission remains to be seen; my guess is that, along with some local heat distribution, we will always need both, with HVDC supergrids still being the best option for very long-distance transmission. But, while the SMR+CCS route to hydrogen production does look costly and inefficient in terms of greenhouse gas emissions, and P2G is moving ahead, the debate over whether hydrogen should play more of a role goes on. The alternative is, of course, to expand and upgrade the power grid beyond what the Committee on Climate Change seems to have in mind for the UK (around 600 TWh capacity by 2050), along with a bit of SMR/CCS hydrogen use for peak heating.
Physics World 31st July 2019 read more »