VOICES | BILL WATTS Hydrogens role in a net zero future With the governments decision on the use of hydrogen for heating expected in 2026, Max Fordhams Bill Watts discusses the options for decarbonising heating systems N obody said decarbonising heat was going to be easy. Current discussion is whether it should be done with decarbonised electricity, preferably with a heat pump, or with decarbonised hydrogen that will replace the natural gas [methane, CH4] in the UKs extensive gas grid. The governments recent backing of hydrogen for transport, energy storage and decarbonised industrial feedstock has kept this debate alive, but not answered it. The thinking engineers money is firmly behind the electrification of heat in buildings for very good reasons, not least that the whole system of renewable generation, electrical distribution and heat pumps is available to use today. By contrast, making zero carbon hydrogen from methane and sequestering the CO2 [blue hydrogen] or, better, from renewable electricity and water [green hydrogen] is still a cottage industry. The safety and viability of converting the gas distribution system in the grid and in buildings from CH4 to H2 is still work in progress. I understand that developing a gas appliance to transition from methane to hydrogen is not that hard and many manufacturers have done the R&D on it. However, most people, including proponents of hydrogen for other uses such as transport, think simply burning it is a criminal waste of a precious resource. Compared to a heat pump that may give you three times more heat than the electricity you put in, a hydrogen boiler might only give 0.5 units of heat per unit of electricity to make green hydrogen a factor of six worse. Given this, installing gas heating and waiting for hydrogen in the grid is not a serious route to decarbonisation. For the whole country to decarbonise, every home will have to move away from gas heating, not just clients who are concerned about climate change and are the thinking engineers customers. A realistic timescale for this is 25 years, so we should not be thinking only about what is available now, but also what the future of energy The thinking engineers money is firmly behind the electrification of heat in buildings for very good reasons BILL WATTS is senior partner at Max Fordham generation and supply will look like. Providing enough zero carbon power to meet our current needs is no trivial matter. More green power is required. I believe that the UK thinks offshore wind will provide its power needs by extending further into deeper water. Perhaps this could be done but it will be hard because of its intermittency. I would like to know if climate change is also likely to exacerbate the intermittency of wind energy in the same way as rain and water supply. One hears about the storms, but prolonged bouts of hot stable air could reduce the availability of wind energy. The solutions to intermittency of any resource is generally a choice of: Collect far more wind and solar energy than needed and waste the excess. Store excess production to use at times of low production. This is the obvious solution. Short-term electrical storage in batteries or physical systems such as pumped hydro/falling weights/ compressed air schemes are viable for short term fluctuations over a day or two, but not months. For this, you need to have a store of chemical energy such as hydrogen. Collect from a wider area on the basis that somewhere is always in surplus to serve areas in deficit. This involves trading the resource with other areas that are in different weather systems or always have a surplus. Finding the right mix is what the next 10 years will be about. Solar and wind fuel is free, and the costs are made up of the infrastructure to capture, store and distribute the energy. Wind installations will generate power at 4p/kWh, but only if most of the power is sold and not wasted. An energy storage system will only earn its keep when it cycles power in and out. Daily storage would produce 365 cycles, whereas monthly would only produce 12 cycles a year to pay for the installation. 20 September 2021 www.cibsejournal.com CIBSE Sep 21 pp20-21 Bill Watts.indd 20 27/08/2021 09:35