Francis Kemausuor

Cassava (Manihot esculenta) and plantain (Musa balbisiana) peels are abundant yet underutilized sources of waste biomass that can be converted into high-quality energy resources. Hydrothermal carbonization (HTC) provides a promising solution by transforming wet biomass into hydrochar at moderate temperatures (160-250°C). This study investigates the effect of process parameters on the yield and Higher Heating Value (HHV) of hydrochar to determine the optimal conditions for maximizing yield and HHV using HTC. The yield and HHV of hydrochar were evaluated as functions of process temperature (160-200°C), residence time (60-180 minutes), and cassava- to-plantain mixing ratio (30:70, 50:50, 70:30). A factorial design approach was employed to optimize these process parameters. HTC experiments were conducted in a 100 mL autoclave batch reactor containing biomass and deionized water, operated under controlled temperature and time conditions. The results revealed that hydrochar yield decreased with increasing temperature and residence time, while HHV increased with these parameters. The maximum hydrochar yield and HHV were 86.29% (wt.%) and 27.84 MJ/kg, respectively. Conversely, the minimum yield and HHV were 64.29% (wt.%) and 16.03 MJ/kg, respectively. Analysis of Variance (ANOVA) indicated that the mixing ratio had no significant effect on hydrochar yield and HHV (P > 0.05). The optimal HTC process parameters were identified as 172.53°C and 155.76 minutes, resulting in a hydrochar yield of 73.08% and HHV of 21.36 MJ/kg. These findings highlight the potential of HTC as an effective method for bioenergy production and waste management, offering a sustainable solution for disposing cassava and plantain peels.

Low-voltage mini-grids play a crucial role in expanding electricity access for rural and remote communities. However, they continue to face technical and operational barriers that hinder their performance and reliability. This study reviewed the evolution of research on technical challenges in low-voltage mini-grids from 2005 to 2025. Using the PRISMA approach, data were extracted from the Scopus database, yielding 155 publications for bibliometric analysis. Bibliometrix in R Studio was used to examine publication trends, geographical contributions, and thematic evolution, while qualitative synthesis identified key engineering and operational constraints. The findings revealed a steady increase in research outputs since 2020, driven by global policy commitments, including Sustainable Development Goal 7 and the Paris Agreement. Persistent technical barriers include voltage and frequency instability, inadequate power quality monitoring, inefficient integration of energy storage, poor control coordination, and limited system design optimisation. African nations contribute less to global research despite being most affected by energy poverty, highlighting capacity and funding gaps. The study highlights the need for integrated solutions combining smart control, hybrid storage, and grid-interconnection technologies to enhance resilience and reliability. For policymakers and practitioners, the findings advocate for investment in research, capacity building, and locally tailored technical standards designed for resource-constrained contexts. This review provides a comprehensive evidence base to guide future research and policy directions aimed at achieving sustainable, technically robust, and financially viable mini-grid systems for universal energy access.

The increasing rate of soil degradation has been a global menace in recent years, predominantly due to human activities. The immediate effects of this challenge are the decline in food production and crop yield in many countries due to poor soil quality. This study, therefore, seeks to determine the effects of different biochar compositions as a soil amendment and to study their effects on soil properties and plant growth. Using a randomised complete block design method, Lettuce seedlings were planted in soil treated with biochar produced from Municipal Solid Waste (MSW) and the catalytic pyrolysis of refuse-derived fuels (RDF) and four (4) different agricultural residues, namely cocopeat, cassava peels, rice husk and bamboo leaves to determine their effects on soil properties and plant growth. Each biochar treatment had a 50:50 and a 75:25 sand-to-biochar ratio, respectively, where growth was monitored weekly for eight (8) weeks. While a 50:50 biochar to soil ratio increased soil ph and electrical conductivity, exponentially affecting plant growth, a 25:75 application rate of cassava peel and rice husk biochar to soil ratios optimally balances soil enhancement and crop yield. The study demonstrated the potential of biochar to enhance soil nutrient content, particularly for Potassium, Calcium and Magnesium. While the study confirmed notable improvements in soil properties, the varying effects of different biochar compositions on plant growth demonstrate the importance of selecting appropriate biochar types and application rates to optimise both soil enhancement and crop yield.

Waste management in most parts of Africa is characterized by the disposal of mixed waste in unengineered landfills. The aim of this study is to assess the environmental impact of mixed waste received at a waste-to-energy plant in Ghana relative to the current model of landfilling. A Life Cycle Assessment was conducted using OpenLCA software version 2.3.1 based on the ReCiPe Midpoint method. For landfilling, LandGEM software version 3.03 was used. The results indicate that waste-to-energy has the potential to provide carbon savings of 3.52 tCO₂eq/ton of waste treated compared to landfilling. Pyrolysis is observed to have high avoided burden across all impact categories, with the lowest Global Warming Potential of −2.3 kgCO₂eq. Anaerobic digestion shows a near neutral environmental impact with the highest value of 47.56 kg 1,4DCB for Terrestrial Ecotoxicity, while Refuse-Derived Fuel and segregation processes show low environmental burdens. The net avoided burden is highest for global warming and non-carcinogenic human toxicity potential. Overall, the hybrid waste-to-energy model is concluded to be an environmentally preferred waste management option compared to conventional landfilling methods, and we recommend that decision-makers facilitate investments into it. It is also recommended for the development of local inventories and databases to encourage more country-specific environmental impact studies and to reduce uncertainty.

Cities in developing countries continue to struggle with mounting waste management challenges. Within a circular economy framework, energy recovery is mostly nonexistent. Against that background, this study aimed to design and assess the viability of a hybrid waste-to-energy facility for the Greater Accra Metropolitan Area (GAMA) in Ghana by 2030. The proposed plant integrates solar PV, anaerobic digestion and pyrolysis to treat unsegregated municipal solid waste. Three cases were developed for different product combinations. Material flow analysis was performed with STAN software 2.7.101. The results indicate that 1.6 million tons of MSW will be generated, to be potentially converted to 271 GWh of electricity, 6400 tons of hydrogen or 4400 tons of bio-compressed natural gas per year, along with additional products: compost, refuse-derived fuel and bio-oil. The economic indicators show that all cases are potentially viable in terms of the net present value (EUR 397 to 1030 million), internal rate of return (14–22%) and levelized cost of energy (0.11–0.18 EUR/kWh). As such, this study proves that waste to energy is a viable waste management solution for large metropolitan areas, with the potential to supply energy, alternative fuels and material products within a circular economy, though it requires the buy-in of policy makers.