Norsk Hydro, later Yara, was founded on the Birkeland plasma arc technology for direct nitrogen fixation from air making calcium nitrate. However, from 1908-1920 the Haber-Bosch ammonia synthesis was developed and took over. For more than 100 years, it has been an apparently unrealistic dream to revive and improve the plasma process, due to fundamental thermodynamic facts, as seen from the chemists’ perspective. The assumption that a temperature of 3,500K is required to get 2% NO from air means a very high energy expenditure per mass nitrogen (~320 GJ/tN). The business case for using electricity is also not favourable relative to the methane-based ammonia process using only 36 GJ/tN. However, even in the 1920s, scientists believed that 60 GJ/tN was theoretically possible and 120 GJ/tN may be the lowest practical value. BASF claimed to make 12% NO in air at 2,300 K. The driving force for further plasma innovation is strong, and a paradigm shift is emerging. This paper and presentation looks at the fundamentals of, and potential for, plasma technology, as well as the business case for using an air-plasma generated acidic nitrate fertiliser product on livestock farms.
Ingels, R.; Graves, D.; Andersson, S.; Koller, R.
University of California, Berkeley
SINTEF Industry / Metal Production and Processing
Vienna University of Technology
Proceedings of the International Fertiliser Society