Comment & Analysis
In the recent Spring Statement the Chancellor Philip Hammond announced that:
- To help meet climate targets, the government will advance the decarbonisation of gas supplies by increasing the proportion of green gas in the grid, helping to reduce dependence on burning fossil-derived natural gas in homes and businesses
- To help ensure consumer energy bills are low and homes are better for the environment, the government will introduce a Future Homes Standard by 2025, so that new build homes are future-proofed with low carbon heating and world-leading levels of energy efficiency. [i]
Although not specifically stated, we have to assume that the reduction in fossil fuel heating and decarbonisation of the gas distribution system includes cooking facilities. This new era of low carbon homes could mean that energy systems and appliances that we are used to seeing in our homes change. We could see new types of boilers and appliances that use fuels we are unfamiliar with to keep us warm and cook our food. Our heating systems will change, with old systems updated to cope with these new fuels and systems that could be detached from a centralised electricity and gas grid, reducing the pressure on these systems as our population grows. It is possible that as appliances come to their natural end of life that new ones can be produced that are ‘green gas’ ready now.
But what does this mean, 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% 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.
When we think about hydrogen and its production we tend to think about it being produced in two main ways, through steam methane reforming or through electrolysis of water. In order for hydrogen to be truly decarbonised it must be considered either:
- Blue hydrogen - produced using stream methane reforming with carbon capture and storage or
- Green hydrogen - this is hydrogen produced renewable or low carbon electricity through electrolysis of water.
These are not the only options and more recently scientists and engineers have been exploring in more detail the opportunities for low carbon coproduction of energy, such as, electricity, gas, heat and fuels and how these can contribute to delivering the very deep cuts in emissions we must make in order to reduce the impacts that climate change will have on us.
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?
The idea of using the heat from a fusion reactor to produce hydrogen through high temperature electrolysis or thermo-chemical cracking of water has been around for about 20 years. But has the time now come where the growing need for green hydrogen and the availability of new technologies and private investment to allow rapid development of fusion coincide?
The decarbonisation of our life support systems will become an increasingly challenging problem for governments and industries all over the globe, so how far can we go on what we already know? Is the fusion global endeavour our only chance of meeting all of the needs of the potential 12 billion residents of Earth? Over the next few articles in this series, the Institution will continue to explore this question.
[i] https://www.gov.uk/government/news/spring-statement-2019-what-you-need-to-know