The MAPSYN project of the European Union (standing for Microwave, Acoustic and Plasma SYNtheses) aims at the utilization of plasma technology for nitrogen fixation reactions on an industrial scale and with industrial plasma reactor technology, developed and utilised commercially [1]. Key motif is enhanced energy efficiency to make an industrial plasma process viable for chemical industry. The corresponding enabling technologies – plasma catalysis, smart reactors (microreactors) and more – go beyond prior approaches. Continuing a first more project-based literature compilation, this overview focus on the two first enabling functions, plasma catalysis and smart reactor technology, which are reviewed for industrial and near-industrial plasma-based applications. It is thereby evident that notable promise is given for the nitrogen fixation as well and indeed this has been demonstrated also for nitrogen fixation; yet, initially and without the holistic system engineering dimension

In many developing countries, including South Africa, water scarcity has resulted in poor sanitation practices. The majority of the sanitation infrastructures in those regions fail to meet basic hygienic standards. This along with the lack of proper sewage/wastewater infrastructure creates significant environmental and public health concerns. A self-sustained, waterless "Nano Membrane Toilet" (NMT) design was proposed as a result of the "Reinvent the Toilet Challenge" funded by the Bill and Melinda Gates Foundation. A "cradle-to-grave" life cycle assessment (LCA) approach was adopted to study the use of NMT in comparison with conventional pour flush toilet (PFT) and urine-diverting dry toilet (UDDT). All three scenarios were applied in the context of South Africa. In addition, a Quantitative Microbial Risk Assessment (QMRA) was used to reflect the impact of the pathogen risk on human health. LCA study showed that UDDT had the best environmental performance, followed by NMT and PFT systems for all impact categories investigated including human health, resource and ecosystem. This was mainly due to the environmental credits associated with the use of urine and compost as fertilizers. However, with the incorporation of the pathogen impact into the human health impact category, the NMT had a significant better performance than the PFT and UDDT systems, which exhibited an impact category value 4E + 04 and 4E + 03 times higher, respectively. Sensitivity analysis identified that the use of ash as fertilizer, electricity generation and the reduction of NOx emissions were the key areas that influenced significantly the environmental performance of the NMT system.

An eco-efficiency analysis has been conducted, as a sustainability performance indicator, by combining the life cycle costs (LCC) and the environmental impacts of diverse plasma-assisted ammonia and nitric acid synthesis routes, for which a detailed process design for small-scale production has been previously reported. The proposed design of the specific plasma processes involves new upstream and downstream activities, which are independent of conventional natural resources and comprise less equipment. In the context of this study, the impact of the product yield and plasma power consumption on the eco-efficiency profiles of the selected plasma processes is evaluated and benchmarked against that of the established synthesis pathways. Results show a relatively improved environmental profile of the plasma-assisted NH ₃ (5% NH ₃ yield), considering a power consumption of 17.2 g NH ₃ kWh ⁻¹ and energy recovery of 5%, against that of the contemporary production route. In the case of the plasma-assisted HNO ₃ (6% NO yield) synthesis, incorporating a power consumption of 7.77 kWh kg ⁻¹ NO and a 20% energy recovery, a better ecological footprint is displayed as compared to the conventional chemical process. Both plasma processes are characterized by higher LCC than the conventional ones, with the plasma-assisted nitric acid displaying a more competitive LCC profile. A clear contribution of the utilities (upstream and downstream equipment) to both the environmental and cost benefits is shown, and the plasma plant is the enabler of such integration. The contribution is related to both the number reduction of equipment (process simplification) and improved operation (process intensification). Given the outcomes of this study, the concept of developing modular plants incorporating the plasma technology and renewable energy sources—e.g. wind power—for synthesizing ammonia and nitric acid demonstrates promising potential and promotes a new window of opportunities for future sustainable decentralized fertilizer production; such as distributed production at the farm site, with the opportunity to react immediately to weather changes and to local conditions (soil, climate, crops, farming business model).

The expected world population growth by 2050 is likely to pose great challenges in the global food demand and, in turn, in the fertilizer consumption. The Food and Agricultural Organization of the United Nations has forecasted that 46% of this projected growth will be attributed to Africa. This, in turn, raises further concerns about the sustainability of Africa’s contemporary fertilizer production, considering also its high dependence on fertilizer imports. Based on these facts, a novel “green” route for the synthesis of fertilizers has been considered in the context of the African agriculture by means of plasma technology. More precisely, a techno-economic feasibility study has been conducted for a small-scale plasma-assisted nitric acid plant located in Kenya and South Africa with respect to the electricity provision by renewable energy sources. In this study, standalone solar and wind power systems, as well as a hybrid system, have been assessed for two different electricity loads against certain economic criteria. The relevant simulations have been carried out in HOMER software and the optimized configurations of each examined renewable power system are presented in this study.