This paper presents the optimal mapping of hybrid energy systems, which are based on wind and PV, with the consideration of energy storage and backup diesel generator, for households in six locations in the South South geopolitical (SS) zone of Nigeria: Benin-city, Warri, Yenagoa, Port Harcourt, Uyo and Calabar. The optima hybrid energy systems are able to meet 7.23 kWh/day of a household's electrical energy. The hybrid energy system for each of the locations was optimally chosen based on HOMER software computation and TOPSIS multi-criteria decision-making algorithm that considers technical, economic, environmental, and sociocultural criteria. Wind energy potential was conducted for the six locations using the Weibull distribution function; the wind speed ranges between 3.21-4.19 m/s at 10m anemological height. The wind speeds and the wind characteristics were extrapolated for 30 m and 50 m hub heights. The solar resource potential across the six locations is also presentedranges between 4.21-4.71 kWh/m 2 /day. The best hybrid system for the locations in Benin-city, Yenagoa and Port Harcourt is the Diesel generator-PV-Wind-Battery system; whereas the best hybrid system for the locations in Warri, Uyo and Calabar is the PV-Wind-Battery system. The hybrid systems in Benin-city, Yenagoa and Port Harcourt emit CO 2 ; only 8.47%, 15.02% and 14.09% of the business as usual (the diesel generator). The payback time ranges between 3.7-5.4 years, using the business as usual cost of energy of 0.893 US$/kWh; whereas the cost of energy of the hybrid systems ranges between 0.459-0.562 US$/kWh, which compares well with available literature in the public domain. The design parameters of the optima hybrid energy systems are also presented. The methodology presented here will serve as a design tool for renewable energy professionals.

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Abstract. Performance of a Sifang mini rice combine, originally developed in China, was evaluated under local farmer field conditions in Benin. Results from field evaluation show that the combine worked satisfactorily on less dense rice fields with minimal weeds at grain moisture contents between 19.1% and 20.1% w.b. on soils with moisture content from 23% to 33% d.b. while causing no significant changes to soil physical properties. With harvesting speed ranging from 0.8 to 4.5 km/h, the harvester had a field capacity of 0.10 to 0.39 ha/h and consumed fuel of up to 11 L/ha while having track slip of 6% to 9%. Harvesting using 2- and 1-L gear offered the best efficiency for IR841 and Nerica L20 rice varieties, respectively. As harvesting speed increased, harvesting efficiency decreased and crop throughput increased irrespective of rice variety. The combine produced low mechanical grain damage with total grain loss ranging from 1.43% to 4.43% and 1.85% to 5.6% for the IR841 and Nerica L20 rice varieties, respectively. At an investment cost of US$5000 and hiring at US$10 per h, owning the mini combine harvester becomes profitable after 342 h of machine use; equivalent to approximately 133 ha of paddy field harvested at a harvesting capacity of 0.39 ha/h. Further testing of the combine under a wide range of crop and soil conditions across different agro-ecological zones and economic comparison with manual harvesting is recommended. This would offer smallholder farmers diverse options of rice harvesting mechanization to facilitate future adoption of improved technologies. Keywords: Crop throughput, Field capacity, Field efficiency, Grain loss, Mini rice combine, Sifang.

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The coastline rural communities in the Niger Delta region of Nigeria have long suffered from the consequences of poor rural electrification, environmental degradation, and health challenges. There is an urgent need to provide an optimal sustainable and environment-friendly energy system for the coastline rural communities in Nigeria, which has the potential of ameliorating the climate change in this country. The HOMER hybrid optimization software and the estimated domestic energy demand of the coastline rural communities were used to determine the best PV solar energy system. The NASA SEE database with monthly averaged values for global horizontal radiation over a 22-year period was considered in the current analysis. The daily energy demand of a typical household in the communities was estimated for the existing energy demand (EED), future electric energy demand (FEED), and future base energy demand (FBED) scenarios as 5.640, 8.830, and 7.233 kWh, respectively. The suggested best energy system has a cost of electricity of 0.651, 0.653, and 0.674 $/kWh for the EED, FEED, and FBED, respectively. The best energy system gives the best components with an appropriate operating strategy to provide an efficient, reliable, cost-effective, and environment-friendly system. It is shown that both positive energy policies of the Federal Government of Nigeria toward renewable energy penetration and the support from the oil-producing companies toward their operational areas would see the cost of electricity being significantly reduced. It is envisaged that the implementation of the suggested energy system with other environmentally responsible interventions would support the Niger-Delta's coastline rural communities, whose livelihoods have been impaired by gas and oil exploration, to attain their full environmental and socioeconomic potentials. ARTICLE HISTORY