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Biomass obtained from agricultural wastes have a high potential for energy generation, particularly in developing countries. The poor properties of the agricultural biomass cause handling problems and limit the suitability as fuel in conventional grates. Densification of biomass into briquettes enhances its fuel properties. In this study, effects of pressure (9, 15 MPa), temperature (90, 120°C), hold time (7.5, 15 minutes) and particle size (< 2.5 mm, > 2.5 mm) on physical properties of corn cob briquettes were investigated using a 2-level full factorial experimental design. A laboratory scale uniaxial briquetting press was used for densification of the milled corn cobs.The properties of briquettes considered are the density, which ranges from 578 to 1,272 kg/m3, and water resistance, which ranges from 32.7 to 94.8%. The empirical models developed for density and water resistance had coefficient of multiple determination for prediction of 80.42% and 95.82% respectively. The significant factors for density of the briquettes were pressure, temperature and particle size. The temperature and particle size along with their interaction was significant in determination of the water resistance. The empirical models predicted experimental data closely.

The production of biogas from peels of watermelon (WP), banana (BP) and potato (PP) was investigated in the laboratory scale using the simple single–state digesters of 1.5 L working volume. The digester was fed on a batch–basis with the slurry of WP, BP and PP containing average moisture content of 18% and operated at temperature of 35°C for 30 days. Measured biogas yields for WP, BP and PP were 0.46, 0.42 and 0.56 m3(kg ODM)−1respectively after 30 days digestion time. Methane production from WP, BP and PP was 0.23 (49.8%), 0.24 (56.55) and 0.30 (53.2%) m3(kg ODM)−1respectively. Results of this study suggest that 24,080 million and 38,520 million kWh of electricity can be generated from biogas at a low–end efficiency of 25% and at the high–end conversion efficiency of 40% respectively using only seven prominent energetically available crop residues in Nigeria.

Agricultural operations have been indicated to be some of the major emitters of greenhouse gases (GHG), particularly methane (CH₄) and nitrous oxide (N₂O) around the globe, and it is important to determine the quantity emitted and how they can be reduced. The environmental impacts associated with field production and industrial processing of soybean into crude vegetable oil in Nigeria was therefore studied using the life cycle impacts assessment tool. The emission from the various inputs into the system was aggregated into a large inventory table. The functional unit was defined as one kilogram of soybean. The environmental impact categories used in this study are global warming, acidification, eutrophication and ozone layer depletion. Of these four environmental impacts, global warming has the highest impact score of 4.7516E–01 kg CO₂ equivalent, followed by eutrophication (1.6414E–04 kg NO₃ equivalent). Ozone layer depletion has the lowest environmental impact score of –2.8207E–07 kg R11 equivalent. The high impact score of global warming is due to the high emission of CO₂ gas from fossil fuel and biomass combustion during field operations and processing of soybeans.

This paper relates to a study on the energy and exergy resources, transfers, consumption and losses in the combustion and heat exchanging units of industrial steam boilers. Mass, energy and exergy analyses, which included the physical and chemical exergies of material streams, were used to investigate the energy resource utilisation of Low Pour Fuel Oil (LPFO) in industrial steam boilers. The chemical exergies of LPFO and the exhaust flue gases were determined as 44,566.66 and 147.97 kJ/kg, respectively, for LPFO undergoing complete combustion process. Higher evaporation ratios and energy consumption by steam were associated with reduction in heat loss. Lower exergy destruction was due to lower rapid changes in temperature potential for the generation of steam in the heat exchanging unit. The average energy and exergy efficiencies of the boilers are obtained as 69.54 and 38.5%, respectively. The exergy efficiencies obtained for the combustion and heat exchanging units for the boilers investigated are given as 55.35, 49.06 and 58.69 and 63.80%, respectively. The results obtained in this study could be applied for energy resources management and control of oil–fired industrial steam boilers.