Keywords: green nitric acid, green ammonia, electrolysis, nitrous oxide abatement.
Increased use of renewable energy is an unavoidable consequence of the call for a reduction in carbon dioxide (CO2) emissions. The path of choice for the ammonia and fertiliser industry is hydrogen from electrolysis of water, using power from renewable sources. Further, expected increases in demand for ammonia for energy storage and transport will lead to a further increase of green ammonia production.
There are certain challenges to the design and operation of green ammonia plants which originate in the fluctuating availability of most types of renewable power. They can be mastered by a combination of partial load and hydrogen buffer storage as described above. Both need careful design based on the expected availability profile of power. It is important to involve a partner such as thyssenkrupp Industrial Solutions with experience both in water electrolysis and ammonia who understands the capabilities and limitations of the whole process chain.
The feasibility of green ammonia projects strongly depends on the cost of the renewable energy, but pressure on conventional production routes e.g. carbon taxes will also play an important role in the future.
Due to the potential lack of CO2 from the process, green ammonia is not suitable for urea fertiliser production, but it is a perfect feed stock for the completely carbon free production of nitrate fertilisers.
Green ammonia is also the starting point for the production of green nitric acid. The environmental impact of the production process can be further reduced by the use of technologies such as EnviNOx®, a tertiary NOx (NO/NO2) and N2O (nitrous oxide) abatement technology abatement technology, developed by thyssenkrupp Industrial Solutions, which can achieve NOx emissions of less than 1 ppm vol., as well as a N2O reduction of greater than 99%. EnviNOx® can be used for different applications with NOx and N2O emissions. Furthermore, with this technology a reduced emissions, colourless start-up of a nitric acid plant can be achieved.
D. Birke, B. Mielke
thyssenkrupp Industrial Solutions AG, Dortmund, Germany
28 pages, 19 figures, 18 references