Tosin Somorin

Thermodynamic analysis of a gamma type Stirling engine in an energy recovery system

Highlights • The performance of Stirling engine integrated to a micro-combustor in the NMT system was investigated.• Energy recovery and power generation of 27 Wh/h from combustion of human faeces.• The integrated position of the Stirling engine to the micro-combustor is highly paramount.• Sensitivity of the performance of the Stirling engine to working gas temperature.• Requirements for optimum performance of the Stirling engine for integration with micro-combustor.

Faecal-wood biomass co-combustion and ash composition analysis

Highlights • Co-combustion analysis was investigated using a bench-scale combustor test rig.• Raw human faeces (FC) contained 73.9 ± 4.4 wt% moisture as received basis.• Blending with wood dust (WD) in a 50:50 ratio reduced moisture levels by ∼40%.• Minimum acceptable blend for combustion without prior drying is 30:70 WD:FC.• Fuel burn rates are 3.18–4.49 g/min for all the blends at air flow of 12–18 L/min.• Oxygen, potassium and calcium are the most abundant elements in faecal ash.

Design and commissioning of a multi-mode prototype for thermochemical conversion of human faeces

Highlights • Ignition, gasification and combustion of simulant and real faeces were studied.• Trials using fuel flowrates of 1.2 g/min and 7.5–8 L/min of air were carried out.• Mean temperatures of 440–670 °C allowed self-sustained combustion.• Maximum temperatures reached for real faeces were in the range of 1210–1240 °C.• Combustion trials lasted up to 160 min without external heat supply.

Probabilistic performance assessment of complex energy process systems – The case of a self-sustained sanitation system

Highlights • A probabilistic model is developed to assess the performance of an NMT.• Energy and environmental performance uncertainties of the system are qualified.• A realistic prediction of the energy and environmental performance of the system.• Probabilistic approach can be applied in other complex engineering systems.

Non-isothermal thermogravimetric kinetic analysis of the thermochemical conversion of human faeces

The “Reinvent the Toilet Challenge” set by the Bill & Melinda Gates Foundation aims to bring access to adequate sanitary systems to billions of people. In response to this challenge, on-site sanitation systems are proposed and being developed globally. These systems require in-situ thermal treatment, processes that are not well understood for human faeces (HF). Thermogravimetric analysis has been used to investigate the pyrolysis, gasification and combustion of HF. The results are compared to the thermal behaviour of simulant faeces (SF) and woody biomass (WB), along with the blends of HF and WB. Kinetic analysis was conducted using non-isothermal kinetics model-free methods, and the thermogravimetric data obtained for the combustion of HF, SS and WB. The results show that the devolatilisation of HF requires higher temperatures and rates are slower those of WB. Minimum temperatures of 475 K are required for fuel ignition. HF and SF showed similar thermal behaviour under pyrolysis, but not under combustion conditions. The activation energy for HF is 157.4 kJ/mol, relatively higher than SS and WB. Reaction order for HF is lower (n = 0.4) to WB (n = 0.6). In-situ treatment of HF in on-site sanitary systems can be designed for slow progressive burn.

Clean Technologies and Innovation in Energy

Developing countries are faced with multiple energy challenges—the dilemma of increasing energy services to billions of people who currently live without electricity, and the need to operate low-carbon, intensive energy systems for environmental sustainability. Clean energy technologies can reduce fossil fuel dependency, provide jobs, and play a central role in improving access to energy; however, there are questions on availability, accessibility, reliability, affordability, and appropriateness of these technologies in developing countries. This chapter provides an overview of the clean energy sources and technologies in Africa. It concludes with case studies of clean energy projects (potential, ongoing, tried and tested) across the different African countries and highlights the challenges, barriers, and approaches to the development, transfer, and diffusion of new and innovative energy technologies.

Conceptual environmental impact assessment of a novel self-sustained sanitation system incorporating a quantitative microbial risk assessment approach

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.