WATER HEATERS | HYDROGEN Chris Goggin Hydrogen ready? Rinnai UK is trialling combustion from hydrogen for its commercial continuous-flow water heaters. Liza Young speaks to the firms operations director about the challenges T o assist the energy trilemma of security, sustainability and affordability, Rinnai UK has been trialling combustion controls with hydrogen for its water heaters. We speak to Chris Goggin, operations director at Rinnai, about the opportunities and challenges of hydrogen appliances. How are the trials going, and what is involved? We have been trialling water heaters and hydrogen for the past three years in different guises, from the full development spectrum. When you put a new product into research and development (R&D), you have to go through a stage-gate process, which should include feasibility, testing and modelling, through to combustion testing and manufacturing. We are at the stage of having manufacturing capability. One of the other things we are preparing for is advanced controls, which have the potential to communicate with other Internet of Things-enabled devices and, potentially, smart meters and grids. If a smart grid is running at 50% hydrogen, for example, then appliances of the future will have to be intelligent enough to know what combustion setting is required and that is something were working on. Organisations are coming out with a boiler that can run off hydrogen, but the challenges are widespread; what percentage is the hydrogen? Will we have to change controls for different gas blends and can we talk to the grid? Rinnai is considering this not only from a combustion and control perspective, but also from a digital and telemetry perspective, which is intriguing and challenging. Were at a stage where we can produce controls that can combust on 100% hydrogen we are testing within facilities around the world on different blends of gas. Well be able to share information with bodies such as [risk management and quality assurance body] DNV GL, which is working on the hydrogen specification for the UK. This is where our advanced capability and facilities can be deployed to the wider hydrogen debate. What is your biggest challenge in converting to hydrogen? What the government is going to do, and whether the industry is prepared for it. Are we going to have a 5% hydrogen and natural gas mix, a 20% mix, or 100% hydrogen straight away? Thats one of the arguments thats going to rage between industry and the government over the coming years what is practical? The biggest challenge for us has been specification of the gas. If we are changing the specification from natural gas to hydrogen, thats going to change the combustion control. So the challenge for us is having a sound industry energy-decarbonisation pathway based around hydrogen. Once we have this, it will make the technological challenge a lot more straightforward. I feel that there is a big industry debate pending, whereby there will be an argument around the specification of the gas. Do manufacturers develop appliances that burn on methane and a per cent of hydrogen and then, later, convert to 100% hydrogen, or do they wait until a hydrogen grid is running? Having a mix is a scenario that is heavily publicised. But this causes problems, potentially, for industry water heaters and boilers, anything that combusts off gas because you have to prepare your appliance for a different mixture, creating additional remedial works. And that mixture isnt the end goal, its only one step towards that end goal of 100% hydrogen. Manufacturers need a clear decarbonisation pathway towards 100% hydrogen. Without that, its a real challenge. What do you need to do to convert water heaters? If we have the right combustion control a specific range of gas then, potentially, we would simply have to change the digital element. This is the brain of the appliance that sets the gas injection and air mix to be relevant to that combustion specification. If we know the specification of the gas, the process of preparing appliances for it becomes a lot more straightforward. Have you got solar/electric heaters? Electrification is an important energy mix for the UK, particularly around London, where there are high-rises so we could well see the introduction of electrical appliances from Rinnai in the future. The Rinnai appliance is a good product to use with boosted hot water. If you were to take solar energy into a thermal store, the unit can modulate its burner and apply the right amount of gas to bring that water up to temperature, therefore applying only the required fossil fuel for boosting the water temperature which harnesses renewable gains. From a technical perspective, the appliance delivers its best performance, from an energy perspective, in a pre-heated renewables environment. What else is Rinnai working on? This year, we launched a stainless-steel water heater a first for the UK market. It has a fully stainless-steel heat exchanger with a zerogovernor gas control. It also has a very easy gas-orifice conversion; this would take about 10 minutes, and combust from natural gas to LPG, or anything else on the horizon for example, hydrogen or other gases. 52 April 2020 www.cibsejournal.com CIBSE Apr20 pp52 Water heaters.indd 52 20/03/2020 17:18