Renewables are beginning to dominate the energy generation sector, favoured for their low-to-zero carbon emissions and, therefore, the potential to meet climate targets. Though powerful and promising, the unreliable nature of such sources means the industry is increasingly seeking new methods of energy storage.
Currently, lithium-ion batteries are the most popular alternative to traditional lead-acid types, due to their longevity and energy density. However, lithium’s rising costs – going up by 240% in 2017 – coupled with fears over resource depletion, are prompting developers to look elsewhere for low-carbon battery bases.
While possible alternatives have been sought in water, gold, cobalt and sodium, the latest development has come from German conglomerate Siemens, which launched its ‘green ammonia energy storage demonstrator’ on 26 June at Harwell in Oxfordshire, UK.
The demonstrator uses renewable power to make ammonia, a compound traditionally used to boost crop yields, by combining hydrogen extracted from water and nitrogen from air. The ammonia is stored in a tank and converted back into electricity when needed, either through traditional combustion methods or by ‘cracking’ it into nitrogen and hydrogen. In the latter method, the hydrogen can then be used in hydrogen fuel cells to power devices such as electric vehicles.
Crucially, no carbon emissions are produced during the entire process.
The £1.5m project was developed in conjunction with the Science and Technology Facilities Council (STFC), the University of Oxford and Cardiff University.
The STFC contributed to the site infrastructure, the wind turbine and expertise in interfacing with its site and systems, while the University of Oxford helped design the ammonia synthesis part of the system. Cardiff University converted a methane-fuelled generator set to run on ammonia.
Siemens programme manager Ian Wilkinson says the company’s interest in ammonia is partially driven by the fact that “it is based on mature technology and is therefore rapidly deployable at sufficient scale to be useful in meaningful decarbonisation”. Having an existing ammonia industry ensures there is infrastructure in place to store, transport and handle the compound safely from the offset.
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