1. Sustainable N fertilizer production based on a loop: Straw - biogas – ‘Haber-Bosch’ process
- Author
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Holger Kirchmann and Göte O.B. Bertilsson
- Subjects
010504 meteorology & atmospheric sciences ,business.industry ,Haber process ,Context (language use) ,04 agricultural and veterinary sciences ,engineering.material ,Straw ,Pulp and paper industry ,01 natural sciences ,law.invention ,Ammonia production ,Biogas ,Natural gas ,law ,Digestate ,040103 agronomy & agriculture ,engineering ,0401 agriculture, forestry, and fisheries ,Environmental science ,Animal Science and Zoology ,Fertilizer ,business ,Agronomy and Crop Science ,0105 earth and related environmental sciences - Abstract
CONTEXT A concept was presented to produce N fertilizer by digesting straw in a biogas plant and transporting bio-methane to a fertilizer plant through a gas grid substituting natural gas. OBJECTIVE The rational was to find out if straw, a residue not infringing on food production and not needing extra cropland, converted to methane in a biogas reactor, is a viable option for ammonia synthesis. METHODS Scenarios calculations were based on straw from 1 ha wheat producing 7 Mg of grain using 150 kg of fertilizer N. Removal rates of straw were 60 or 100%. Digestion residues were returned to fields within a radius of 50 km. Three scenarios with varying straw removal and low to high efficiency of the biogas and fertilizer plant were assessed. RESULTS AND CONCLUSIONS A sensitivity analysis showed the combination of a medium to high efficient biogas and fertilizer plant using between 3.5 and 7 Mg straw covered the energy need for crop management, transportation of straw and digestate and N fertilizer production and still delivered a surplus of 838–9192 kWha ha−1. The amount of 1 Mg of straw enabled the production of 94 to 173 kg fertilizer N. SIGNIFICANCE Use of straw can be a useful alternative for N fertilizer production making agriculture more sustainable.
- Published
- 2021
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