Source: SiemensAmmonia could be used to store renewable energy and as a source of hydrogen for fuel cell-powered vehicles, thanks to a pilot project developed by Siemens, the Science and Technology Facilities Council, the University of Oxford and Cardiff University.

The Green Ammonia Energy Storage Demonstrator in Oxfordshire, U.K., facilitates the complete cycle of renewable power, storage as ammonia and conversion back to electricity.

Ammonia plants currently use natural gas or other fossil feedstocks to provide the energy required to power the synthesis process, and as a source of hydrogen. Large quantities of carbon dioxide are released by these facilities.

Water electrolysis serves to provide a hydrogen supply in the demonstrator, which extracts nitrogen from the air. The system uses renewable energy for this application, and combines the two elements in an established high-temperature, high-pressure Haber-Bosch process to make carbon-free ammonia as a practical bulk energy source.

The new technique could be used as a means to store excess electricity produced by intermittent renewable energy sources. The ammonia can be consumed as a fuel in gas turbines, for use at times when the sun is not shining or the wind is not blowing.

Using renewable electricity to make ammonia for fertilizer manufacturing has the potential to save more than 40 million tons of carbon dioxide annually in Europe alone, and over 360 million tons worldwide.