As an energy carrier, hydrogen can play a significant role in energy security, carbon reduction and economic growth. It will be a crucial component of a net zero energy system.
Hydrogen is invisible, odourless and non-toxic, and has been used safely for many decades in a wide range of applications, including the food, metal, glass and chemical industries. The global hydrogen industry is well established and produces 50 million tonnes of hydrogen per year.
The following make hydrogen an excellent fuel for a range of applications:
- Zero to near-zero carbon footprint depending on the method of production;
- Range of production methods, leading to fuel flexibility and energy security benefits (see below);
- Available as a waste stream for capture from a variety of industrial processes (including carbon capture and storage);
- Safe to produce, store, transport and use in fuel cells and internal combustion engines; and
- Able to act as an energy buffer, thus helping to overcome renewable intermittency issues and deliver grid balancing.
There are various ways to produce low carbon hydrogen – ranging from steam methane reforming combined with carbon capture and storage to water electrolysis and use of waste streams. Other routes to hydrogen are expected to be commercially developed; one example is via the utilisation of nuclear heat.
It is expected that no single hydrogen production method will dominate future markets. All production methods could be a part of the future hydrogen energy portfolio; this will provide greater flexibility and resilience to the system than would be the case with any single method.
Hydrogen can be stored:
- At pressure – in cylinders typically at 200 or 350 bar. For stationary purposes, hydrogen pressure vessels are used. Where larger volume of storage is required, underground storage in salt caverns is also practised.
- As a liquid – hydrogen can be stored at -253 C.
- In a solid form – where hydrogen reacts with metals to form various forms of solid metal hydride, which can then release the hydrogen under controlled conditions on demand.
Hydrogen is currently delivered in gaseous form using tube trailers or cylinders, and in liquid form in cryogenic liquid hydrogen tankers; pipelines are used to a very limited extent.
Hydrogen Refuelling Infrastructure
The widespread deployment of hydrogen powered vehicles will require an extensive refuelling network. The development of such a network will take time and occur in phases. The initial stages are already in place, with refuelling facilities at a number of locations supporting captured fleets of vehicles. In selected areas, the establishment of several refuelling stations has resulted in the formation of clusters, which allow vehicles to extend their range beyond that afforded by single sites. Over time, and as further clusters develop, a comprehensive infrastructure will evolve. Whilst the bulk of investment in hydrogen refuelling infrastructure can be expected to be made by the private sector, financial assistance for the initial network from Government will continue to be important in the short-term.
Hydrogen for Heat
Hydrogen is recognised as a key solution to help decarbonise the energy system and could play a valuable role in delivering low carbon heating for UK buildings and industrial processes. The role of hydrogen as a heating solution is currently being explored by the Government’s ‘Hy4Heat’ programme and a plethora of ongoing studies and projects.