Why hydrogen for clean energy?
The 2008 Climate Change Act has set the UK a legal obligation to reduce CO2 emissions by 80% by 2025. To do this we need to find ways of decarbonising our energy systems. Hydrogen could provide clean energy for our homes, businesses and transport networks.
Hydrogen is a chemical element that exists naturally and unlike fossil fuels will never run out. It offers a way to deliver low carbon energy because when it is burned it doesn’t produce CO2, just water and heat.
A flexible energy source, it is already being used to manage the electricity grid, fuel vehicle fleets and industry. Helping to meet climate change and clean air targets, hydrogen could be a vital part of the UK’s low carbon energy future. Decades of research, development and testing have shown that hydrogen technology is a workable, economically viable alternative to fossil fuels which could be deployed across the UK.
Hydrogen has an important role in balancing a whole energy system. Renewable energy from wind and solar can be, and is currently, used to produce hydrogen via electrolysis existing refuelling stations are supplied in this way. This can be injected directly into the gas network for heat or transport, or stored for future use or dispatchable power. This process is known as Power-to-Gas or Power-to-Power. It maximises the benefits from intermittent renewable energy sources where supply does not always match demand.
This flexible provision of energy from hydrogen can help to balance the grid, and provide improved energy security by storing significant amounts of energy for use when needed. It also supports growth of the renewable energy market. As electrolyser technologies improve and decline in price, the production, storage and provision of hydrogen via these processes is likely to increase.
We still rely heavily on fossil fuels (mainly natural gas) for heating our homes and businesses. The natural gas distribution networks are currently connected to more than 20 million UK homes, providing gas for heating and cooking; supplying around twice as much energy as the electricity network. By using the existing gas network, hydrogen could be used as an economical heat source which would reduce our impact on the environment. Studies are underway (HyDeploy) to test how hydrogen blending could be used for supplying heat to UK homes, without the need for replacement of domestic appliances.
DID YOU KNOW? Using hydrogen for heat isn’t new: prior to North Sea gas, homes were heated by town gas produced from coal, which contained around 50% hydrogen.
While the UK has dramatically cut its greenhouse gases from industry and power generation, the emissions from transport have seen little change over the last 25 years. Great strides have been made with the growth of electric vehicles, however this puts additional strain on local electricity networks, particularly at peak demand periods.
Fuel cell electric vehicles (including cars, buses and trains) combined with a network of re-fuelling stations could help address this challenge.Bus fleets in London and Aberdeen are now using hydrogen as a fuel, there is also a growing national network of hydrogen refuelling stations. Work is underway at Alstom’s Wigan facility for the use of hydrogen powered trains, whilst marine applications of hydrogen are already in place in Liverpool and Scotland. Liverpool based ULEMCo has converted several commercial vehicles to run on a dual fuel system of diesel and hydrogen and can also significantly extend the range of electric vehicles by adding a hydrogen fuel cell
In petrol and diesel cars, the burning of fuel produces carbon dioxide and water. In hydrogen cars hydrogen reacts with oxygen in a fuel cell, making electricity to run the car. The only by-product of this process is water vapour.
Efficient and cost effective hydrogen storage is vital to maximise its role in a whole energy system. Hydrogen can be stored as a gas or as a liquid, in large amounts and for long periods of time.
Pressurised hydrogen can be stored in several ways and efficient hydrogen storage is an active research area. For use in the gas network, hydrogen can be stored as pressurised gas ready for use in the pipes, or at a much larger scale, in salt caverns.
The North West has several sites with correct geology for hydrogen storage, such as the Cheshire Salt Caverns. Similar storage sites are already being safely used elsewhere in the UK. The Cheshire caverns have the largest UK storage capacity, excellent geological properties and are one of the more cost effective options, making them a preferred site for development.
Hydrogen can also be transported in pressurised tanks or bottles or be stored and used in fuel cells, which generate electricity.