TECHNOLOGY | HYDROGEN-READY BOILERS FUEL FOR THOUGHT Worcester Bosch and Baxi Heating have revealed plans for hydrogen gas boilers. Phil Lattimore looks at the technology, while Worcester Boschs Martyn Bridges explains where he thinks hydrogen can replace natural gas W ith heating accounting for around half of UK energy consumption and around a third of greenhouse gas (GHG) emissions, removing carbon from heating and hot-water supply has become a key issue if the UK is to meet its 2050 zero carbon targets. One solution thats gaining traction is replacing natural gas with hydrogen, converting the UKs existing gas infrastructure to be used with this low carbon alternative. Several trials are under way for domestic and commercial hydrogen solutions that could use existing pipework, some of which have been covered previously in CIBSE Journal (see In the pipeline, October 2019). As the UK government considers its decarbonisation plans for heat and hot-water generation, Worcester Bosch has announced the countrys first boiler system capable of running on 100% hydrogen, while Baxi Heating has said it will launch live trials of hydrogen boilers in the UK this year. As well as burning hydrogen the only by product of which is water the prototypes run on natural gas. This means they could be deployed now and converted to a hydrogen gas supply if/when this becomes a reality, with no need for an entirely new heating system to be installed. Commerical rollout While demonstrating their capability for developing the technology, Worcester Bosch and Baxi Heating concede that a full commercial rollout of hydrogen-ready boilers is still a few years away. Martyn Bridges, technical director of Worcester Bosch Group, explains that it is supplying two prototype boilers for a showcase event by the Department for Business, Energy and Industrial Strategy (BEIS) in the first quarter of this year. More units will then be produced for a more extensive trial towards the end of 2020. To fully commercialise this product, however, were awaiting a government decision that it is going to press the green button for hydrogen, Bridges says. Once we have that, we could have them commercially available in the volumes we sell now by 2025. Jeff House, head of external affairs at Baxi Heating, says his companys hydrogen boilers (like Worcester Boschs) will be used as part of the Hy4Heat trial programme over the coming months, and further trials are scheduled. Once theres a bit of certainty that it is a firm government objective, we can prepare for commercial production, House says. Both firms believe a commitment from government to hydrogen as part of a low carbon energy strategy and to a date from which only hydrogen-ready boilers can be sold would be the green light for the UK industry and supply chain to ramp up investment in the technology. Flashback prevention Hydrogen has a higher flame speed than natural gas. One of the key technical advances in hydrogen boilers are burners, which can hold a stable hydrogen flame against its high speed. Gas-air ratio control Hydrogen has very similar energy-flow properties to natural gas, so the new components will be very similar. Condensate Hydrogen produces significantly more condensate than natural gas. This must be considered in heat-cell design. Materials compatibility At the low pressures used in small boilers, most materials currently used for natural gas will be suitable for hydrogen. Flame detection Hydrogen flames are invisible and create no electrical signal, but can be detected by its ultraviolet (UV) emissions. Conversion To minimise the impact of conversion, boilers will be developed to be quickly and easily reconfigured for hydrogen on conversion day. Performance The output, efficiency and emissions of hydrogen appliances will be similar to those of natural gas boilers. The products of combustion are very clean. Gas-tightness Hydrogen has a small molecule size. However, leakage rates are similar to natural gas and there is unlikely to be a need for significant re-engineering. Worcester Boschs hydrogen boiler www.cibsejournal.com February 2020 53 CIBSE Feb20 pp53-54 Hydrogen boilers.indd 53 24/01/2020 15:08