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NETWORK / 37 / OCTOBER 2019 explosive event in the system." From the literature review, typical syngas mixtures were tested in laboratory equipment to identify areas of interest. The downstream equipment heat recovery steam generating boiler (HRSG) used was a 1/7th scale model of a (HRSG) typical GE350MW gas turbine which was developed to under - stand when the actual issues might be if a combustion event occurred in the system. To ensure a cleaner combustion system, the hot gas flow was generated using a Rolls Royce Viper 301 gas turbine, converted to run on Butane. In this test rig the ETI have conducted 150 experiments using various hydrogen mixtures from pure hydrogen to mixtures of hydrogen, carbon monoxide and methane. Winstanley added: "The results showed that hydrogen and hydrogen and carbon monoxide mixtures were more reactive than methane or hydrogen and methane mixtures. Our research also showed hydro - gen and hydrogen and carbon monoxide DECARBONISATION OF HEAT mixtures could auto-ignite under certain circumstances, particularly when exhaust temperatures were above 350°C. On the other hand, methane had a moderating ef - fect on these more reactive mixtures." The test rig is still operational and availa- ble for further research work at HSL Buxton. The experiments and information provided are set to be of value to the hydrogen pro- jects currently being undertaken in the UK. The conversion With other trials and projects taking place to prove that hydrogen can be integrated into the energy system, both Clarke and Winstanley remain optimistic about its potential. When it comes to the repurposing of the existing natural gas network to distribute hydrogen to industry and domestic proper- ties, Clarke uses the analogy of Wales & West's gas mains replacement programme, as evidence that it is something that could be achieved. "Part of this is to get every single house in a street to convert their pipework outside, from steel and cast iron to plastic. It can be pretty intrusive – there are holes in the road and maybe in people's drives. On the day of conversion from one pipe system to the other everyone in the street has got to be in so that the gas can be turned off and then back on again. Gas networks are really good at doing this. We do 400,000 of these across the country. So, the timescales (for hydro - gen conversion) could be achieved. It would just have to be done in a well organised way." 'Town' gas, which was used in the UK gas network until the 1970s, was made up of up to 60% hydrogen. Last year, Mark Horsley – chief executive of Northern Gas Networks – told Network: "I remember my grandparents' house being converted in the late 1960s. Town gas was called 'derived gas', which was close to 50 per cent hydrogen at that time. When they moved to natural gas there was a concern from engineers that it would be more unsafe. "Engaging with customers in this and putting them at the heart of everything we're doing is so important for them to gain an understanding of what we're putting in as a new technology." Winstanley commented: "We did a large switch in the 1970s where we went from town gas to natural gas. These things can be managed if they're done properly. Consum - ers probably wouldn't notice 20 per cent hydrogen methane. It's a seamless invisible change to reducing carbon emissions." Looking ahead, both Clarke and Win - stanley agree that whilst there is clearly interest in creating a hydrogen economy, the government must show greater leadership to push the agenda forward. "The government have got to get behind the decarbonisation of the gas grid," notes Clarke. "BEIS need to see a net-zero gas grid as something that can be done. We're producing business plans that will have that ambition and the pathway to get there. Gov - ernment and regulators have got to get be- hind it. HSE have really dedicated resource to it. Ofgem seem stuck in a position of saying they don't know which way to turn, but they've got a role to play in net-zero. We need to try and pull together a group of people who will show some leadership and drive it forward." Winstanley remarked that "the natural gas network is probably one of the most challenging things to decarbonise in the UK", but concluded by saying: "I think there's great potential for hydrogen. It's a lot brighter than it has ever been."