Siemens is preparing to launch its Green Ammonia Energy Storage Demonstrator, in Oxfordshire. UK, on 26 June. The £1.5 million pilot project, developed by Siemens in conjunction with the Science and Technology Facilities Council, the University of Oxford and Cardiff University, has developed the world’s first demonstrator to show the complete cycle of renewable power, storage as ammonia (NH3), and conversion back to electricity.Ammonia is already produced in vast quantities, mostly for agricultural fertilisers. Today’s ammonia plants use natural gas or other fossil feedstocks to provide the energy required to power the synthesis process, and as a source of hydrogen. As a result, ammonia production by these methods releases large quantities of CO2.
The Siemens demonstrator uses electrolysis of water to provide a hydrogen supply, and extracts nitrogen from the air. The system is designed to use renewable energy to do this, and to combine the two elements in an established Haber-Bosch process to make ammonia. Ammonia produced in this way can be a completely carbon-free and practical bulk energy source.
Using renewable electricity to make ammonia for fertiliser manufacturing has the potential to save more than 40 million tons of CO2 each year in Europe alone, and over 360 million tons worldwide.
Ammonia can also be used as a fuel for gas turbine engines generating electricity at times when renewable energy is not available. Therefore it provides a solution to storing energy in sufficient quantities, for a long enough time, to balance significant demands for power and the availability of renewable energy.
When burned, ammonia breaks won into into nitrogen and water, and doesn’t suffer the CO2 emissions associated with fossil fuels. Although the presence of nitrogen in the fuel carries a possibility of additional NOx emissions, low-NOx ammonia combustion is an active research area and there are well-established selective catalytic reduction processes readily available to remove NOx from exhaust gases.
Ammonia is already transported in bulk over long distances by sea, allowing exports of low carbon energy to countries with limited local renewable resources. The energy can then be released, either in the traditional way by combustion in a gas turbine, or by ‘cracking’ it back into nitrogen and hydrogen and using the hydrogen in a fuel cell – to power electric vehicles, for example.
The demonstrator project is part of the Innovate UK Decoupled Green Energy project budget and has been funded with approximately £500 000 from Siemens, and £1 million from Innovate UK.