Renewed sanitation technology: A highly efficient faecal-sludge gasification–solid oxide fuel cell power plant

Sustainable development goals for 2030 aim at the extensive reduction of the global sanitation breach; this might be achieved by renewed sanitation technologies and while providing sanitation recover valuable products such as energy. Consequently, this work presents a gasification–solid oxide fuel cell (SOFC) power plant that was configured for high-efficiency energy recovery from faecal sludge. The main limitations of faecal sludge gasification are the production of impurities, such as tar, and the high energy requirements for both the endothermic gasification process and removing the high moisture content in the feedstock. However, results from this work indicate that a superheated steam dryer combined with an indirectly heated multistage gasifier and a gas-cleaning unit can overcome the mentioned limitations. The external heat for the gasifier is supplied by the process heat available and a microwave plasma torch, and there is sufficient heat to drive a micro steam turbine. Thermodynamic calculations indicated that the plant could reach a net electrical efficiency of the order of 65%. As a result, a gasification–SOFC power plant is more suitable for energy recovery than any other process such as biochar production by pyrolysis; hence, it might become a technology that is financially feasible and can be used globally for sanitation purposes.