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Bioelectrochemical systems (BES) are commonly utilized to generate green electricity, chemicals, and materials through bioelectrocatalytic processes. Over the years, the growing interests in low carbon energy, wastes valorization and the sustainable bioremediation of environmental pollutants have generated interests in BES such as microbial fuel cells (MFC) and bioelectrochemical fuel cells (BFC). The MFCs are the most advanced BES that can ensure the microbial conversion of chemical energy into electrical energy. Therefore, this article seeks to review and present valuable literature on the fundamental operational principles, mechanisms and understanding of BES such as MFCs. It seeks to highlight the schematics of these systems along with the processes and mechanisms such as the oxidation of organic substrates ranging from acetate compounds to complex mixtures. Furthermore, the prospects, challenges, and future applications of BES technologies are presented. The findings indicate that BFCs and MFCs are hampered by low efficiencies, energy output, mass transfer, porosity, and proton conductivity of the electrode and membrane materials along with mechanical strength, scalability, biocompatibility, and chemical stability. However, BES could potentially impact on clean energy production, greenhouse gases mitigation, wastewater treatment, bioanalysis, biosensors, and environmental remediation in the future.

This study seeks to characterize and highlight the fuel properties, rank, and classification of coals from Ihioma (IHM) and Ogboligbo (OGB) in Imo and Kogi states of Nigeria, respectively. The fuel properties were examined based on ultimate, proximate, and bomb calorific analyses. The results indicated that IHM coal contains comparatively higher C and H but lower O, N, and S content than OGB. In addition, the nitrogen (N) and sulphur (S) content for both coal samples were above 0.7 wt.% and 1.5 wt.%, respectively, which indicates high potential for pollutant emissions. Furthermore, the coal proximate properties were below 5 wt.% for Moisture; Volatiles (70 wt.%); Fixed Carbon (45 wt.%) and Ash (2.5 wt.%) on average. IHM coal has an HHV of 19.40 MJ/kg whereas OGB is 15.55 MJ/kg. This is due to the low carbon (C), hydrogen (H) and high oxygen (O) content in OGB whereas IHM contains higher VM and HHV. Furthermore, OGB presents better handling, storage, and transport potential. Furthermore, OGB has a higher fuel ratio and value index due to lower moisture, ash content, and volatiles. Based on the ASTM D388 standard, the coals were classified as Lignite (Brown) Low-Rank Coals (LRCs) with potential for energy recovery.

The lack of comprehensive data on the fuel properties of newly discovered coal deposits in Nigeria has hampered the prospective utilisation for power generation. Consequently, this study is aimed at characterising the physicochemical and thermokinetic properties of Shankodi-Jangwa (SKJ) coal recently discovered in Nassarawa state, Nigeria. The results indicate that SKJ comprises 40.50% fixed carbon, 43.34% volatile matter, and 2.36% sulphur with a higher heating value (HHV) of 27.37 MJ kg-1. Based on this HHV, SKJ was classified as high-volatile B bituminous coal. Thermal analysis of SKJ under oxidative thermogravimetry (TG) at multiple heating rates revealed that SKJ is highly reactive and thermally degradable below 1000°C. Kinetic analysis using the Flynn-Wall-Ozawa model for conversions α = 0.05-0.90 revealed the activation energy to range from E a = 113-259 kJ mol-1 , with the frequency factor ranging from A = 2.9 × 10 13-1.5 × 10 23 min-1 and a range in R 2 = 0.8536-0.9997; the average values of these ranges are E a = 184 kJ mol-1 , A = 9.2 × 10 23 min-1 and R 2 = 0.9420, respectively. The study highlighted fuel property data vital for modelling and designing future SKJ coal power generation.

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