It could herald an end to fossil fuel heating and cooking, but can green hydrogen be sourced at scale? IMechE’s Dr Jen Baxter mulls some of the options. What is green gas and where does it come from? It is a good question and in general seems to mean methane gas CH4 created using wastes, such as food, farm and landfill and is otherwise referred to as biomethane. This gas, when burnt, behaves in the same way as natural gas, producing carbon dioxide, but is considered to be greener as it uses wastes to produce it reducing methane emissions from rotting waste, a more potent greenhouse gas than carbon dioxide. However, looking further into the future and for greater decarbonisation there is another green gas we can consider, hydrogen. Hydrogen is a gas that when combusted produces water and no CO2. However, hydrogen does not occur on its own on Earth, it must be extracted from other matter, such as fossil fuels or water, which adds an additional component to the process. There are a number of different ways that hydrogen can be produced – it can be used for electricity generation, heat generation and as a fuel for clean vehicles. Currently hydrogen can also be added to the gas distribution network, the system that provides domestic gas, and could potentially rise to 20 per cent of the network’s volume with very little need for change to this system. This flexibility means that hydrogen offers us exciting options for rapid deployment at scale if it is produced in a ‘green’ way. The most efficient electrolysis is often done at high temperatures, so looking at the technologies that can give us this, a constant supply of low carbon electricity and an opportunity to co-produce and locate, nuclear fission with hydrogen becomes an excellent proposition. With this will also come the opportunity for desalination, the intersection of our future power and water needs. Providing fresh, safe water in parts of the UK and globally will become increasingly challenging. Today our high temperature reactors can and do produce hydrogen, some through the use of electrolysis and some through the thermal-chemical cracking of water. These techniques could be scaled up for the needs of tomorrow and when tomorrow comes could nuclear fusion become the ideal source of heat at high temperature?
Business Green 18th April 2019 read more »