Internalisation of environmental costs of decentralised nitrogen fertilisers production

Abstract

Purpose Ammonia (NH3) production is an energy-intensive process that is concentrated in a few countries at large-scale plants, mainly using the Haber–Bosch (HB) process. Local plants next to farmers can reduce environmental impacts, as well as reduce storage, shortage risks, and price volatility of fertilisers. Since local NH3 production is not cost-effective, we analyse how internalisation of environmental impacts into economic analyses could help to promote novel technologies for NH3 synthesis when supplied with renewable energy. Methods Mini-HB plants working at high pressure and temperature, as well as novel alternatives based on plasma reactors working at ambient conditions and using electricity from renewable sources, have been recently proposed for decentralised NH3 production. To evaluate the environmental performances of these alternative and traditional NH3 pathways, a life cycle assessment was performed to quantify the reduced emissions in each production process and the impacts of by-product utilisation, such as steam, oxygen, or carbon black. Different scales of storage and transportation, fuelled by traditional energy sources, were modelled to quantify the impacts of the simplified NH3 supply chains. A review of monetary valuation coefficients was performed to internalise the life cycle environmental impacts into the techno-economic analyses of NH3 production in Australia. Results and discussion Most of the estimated environmental costs were due to the carbon emissions of conventional plants and thermal plasma plants because of the use of fossil-based electricity. However, the high external costs associated with the photochemical oxidant formation and particulate matter affected the thermal plasma and non-thermal plasma (NTP) plants, costing in total 9,500 and 4,200 $/t NH3, respectively, due to the impacts of solar panels manufacturing. In contrast, electrolyser-HB plants obtained rates of 114 $/t NH3 because of the high energy efficiency and oxygen sales. In the future scenario for NTP-based plants, this alternative could also be competitive with rates of 222 $/t NH3. Additionally, the estimated total external costs for the conventional NH3 industry in Australia amounted to about US$5 billion per year. Conclusions Electrolyser-HB plants could be cost-effective in the short term due to the energy efficiency of HB processes. However, the HB process has reached its efficiency limits, while the NTP process still has room for improvement, as well as its production costs are lower at smaller scales. In addition, if monetised environmental costs are analysed for a whole industry, public administrations could be prompted to invest the expected savings in the promotion of these novel technologies.

Down-streaming Small-Scale Green Ammonia to Nitrogen-Phosphorus Fertilizer Tablets for Rural Communities

“…The above finding is consistent with that of a previous report [5], which stated that decentralized and renewable energy-based fertilizer production generates fewer pollutants than traditional production lines. Although these fertilizers are environmentally friendly and beneficial, their commercial viability continues to impede the adoption of alternative technologies.…”

“…Osorio-Tejada et al [5] studies have highlighted that the small-scale distribution of ammonia near farmers can result in co-benefits such as local employment, resource utilization, technology transfer, and knowledge transfer; crop intensification through customized fertilizer production; environmental benefits due to the use of clean energy sources; and minimized global and supply chain issues. Since the goal is to decarbonize the entire fertilizer industry, there must be alternative strategies for reducing the environmental impact of fertilizer use [6].…”

“…Note:1 Cation exchange capacity; 2 Cation exchange value; 3 Atomic absorption spectroscopy;4 Aluminum content in the soil;5 Centimoles per kilogram;6 Part per million.…”

What Metals Should Be Used to Mediate Electrosynthesis of Ammonia from Nitrogen and Hydrogen from a Thermodynamic Standpoint?

“…Finally, there is a strong ongoing thrust to pursue sustainable industrial production of ammonia to meet the urgent requirements of carbon neutrality. , Coupling green H 2 from water electrolysis with the H–B process, also known as the green H–B process, has been actively exercised on a large scale globally. However, despite the low transportation costs associated with localized productions of ammonia for the green process, the traditional SMR route retains significant cost advantages, primarily attributed to the high electricity costs involved in water electrolysis . Additionally, unstable production of H 2 from intermittent solar or wind power sources also leads to a low rate of equipment utilization and requires further technical developments to produce ammonia dynamically.…”

“…However, despite the low transportation costs associated with localized productions of ammonia for the green process, the traditional SMR route retains significant cost advantages, primarily attributed to the high electricity costs involved in water electrolysis. 44 Additionally, unstable production of H 2 from intermittent solar or wind power sources also leads to a low rate of equipment utilization and requires further technical developments to produce ammonia dynamically. Direct electrosynthesis of ammonia may provide new opportunities for localized production provided that economically competitive methods can be developed to address the issues such as high energetic cost and purification of ammonia from the electrolyte solution.…”