Techno-Economic Analysis of a Cogeneration System for Post-Harvest Loss Reduction: A Case Study in Sub-Saharan Rural Community (original) (raw)
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Energy Conversion and Management, 2019
Sub-Saharan African region currently suffers from the lack of clean energy and heavy postharvest loss. Hence, a biogas driven combined cooling, heating and power generation system that harmonises power generation with food drying and cold storage is studied in the context of current renewable energy policies of the Nigerian government. Wastes from a community cattle market are assessed for biogas generation that is subsequently used to power a 72 kW internal combustion engine. Heat is recovered from the engine to drive a cabinet dryer, an absorption chiller and maintain anaerobic digestion process. The model is developed in Aspen Plus and the results are used to evaluate the economic viability of the system. The electricity and tri-generation efficiencies are 25.7% and 74.5%, respectively. Results also suggest that energy demand of 407 farmers can be met including drying of 12,190 kg of cassava, 3,985 kg of maize and cold-storage of 6,080 kg of tomato per farmer every year. At $0.05•kWh −1 of electricity, the discounted payback period varies between 2.5 and 4.7 years depending on agricultural product processed. Levelised cost of energy and profitability index are also sensitive to both interest rate and plant's availability which become uneconomical above 9% and below 80%, respectively.
One third of the global food production ends up in the bins such that food waste now ranks third when placed amongst the world's CO2 emitters. Bulk of food waste occurs at the early stage of food value chain in the developing countries where food insecurity also prevails for many people. To reduce this trend, a biogas driven tri-generation system which synchronizes power generation with food drying and cold room storage is designed and analyzed in context of the current renewable energy policy of the Nigerian government. Using Aspen Plus simulator, market wastes from a rural community is analyzed for biogas generation. The biogas is subsequently used to fuel a 72kWe internal combustion engine which drives a generator to generate electricity. The recovered heat from the engine's exhaust is used for drying and cooling of agricultural products while heat from the cooling jacket is used to maintain the anaerobic digestion process. The results from this study shows that the system's efficiency increases from 25.66% to 76.02% for electricity only and tri-generation respectively. The results also indicates that the systems is able to provide electricity, drying energy requirements and postharvest cold storage for 322, 56, and 922 farming households respectively. This amounts to drying of 20.35MT, 2.313MT and 3.75MT of cassava tubers, maize and tomato respectively per household per year while 3.75MT of tomato is also cold stored. The results equally demonstrate that with the current electricity tariffs for remote areas being charged at USD 13.1/MWh and Feed-in Tariffs (FITs) of USD 122.48/MWh, Net Present Value is positive regardless of FITs availability and the current banks' lending rates. However, the payback period is sensitive to FITs and lending rates and varies between 2.1years to 7.19 years depending on the lending rates.
Biomass conversion and biorefinery, 2024
In response to declining electricity production in Zimbabwe, the energy regulator engaged various stakeholders to work together to solve the energy shortage problem. Biomass waste, abundant in the country, can contribute to electricity generation for consumption and export to the grid. Compared to other renewable energy resources such as wind and solar, biomass has lower investment and per unit operational costs, making it more affordable. Although farmers in the remote off-grid areas produce large amounts of waste, which can be used for biogas production via anaerobic digestion (AD), the farmers are still 'energy-poor'. There is insufficient information to enable farmers to make informed decisions on AD technology uptake. This study conducted a techno-economic assessment for a mini biogas electric plant (MBEP) for a typical farm in Zimbabwe's off-grid areas. The sustainably available biomass for biogas production was determined, followed by quantifying the biogas produced, sizing and selecting the digester type, and sizing the generator. The MBEP produces 435,350.7 kWh of heat and electrical energy from 452 t of biowaste. The first biodigester-type option, the garage-shaped, has a negative net present value (NPV) of − US$416.4. The Carmatec biodigester, the most popular AD technology in the country, has a positive NPV (US$216,447.7), but its economics needs improvement. Adopting AD technology allows farmers to mitigate environmental pollution and improve soil fertility by converting organic waste into biogas and biofertilisers and promoting sustainable agricultural practices. Research was recommended to investigate supportive policies, incentives, and regulatory frameworks to promote the widespread adoption of AD technology in agricultural settings. Keywords Anaerobic digestion • Biogas • Sustainably available biomass • Economically viable • Net present value Abbreviations AD Anaerobic digestion ARR Average rate of return CF Cash flow CHP Combined heat and power GHG Greenhouse gases HSW Household solid waste IRR Internal rate of return MCA Multi-criteria analysis MBEP Mini biogas-electric plant NPV Net present value O & M Operational and maintenance PBP Payback period REIPPPP Renewable Energy Independent Power Producers Procurement Program Nomenclature r Bank interest rate (discounting factor) T s,cw Total amount of sustainable crop wastes (t/y) y c Crop yield (t/y) Waste-product ratio rr Waste removal rate (%) U comp Competing uses of crop waste N a Number of specific animals kept on the farm Amount of dry waste produced (kg/animal/d) wc Waste collection efficiency (%) N p Number of people on the farm T d∕s Total biomass produced by each species (t/d) s Species biogas yield factor (m 3 /t) * Chipo Shonhiwa
Evaluation of CHP for Electricity and Drying of Agricultural Products in a Nigerian Rural Community
The techno-economic performance analysis of biogas production, power generation and recovery of heat for drying of agricultural products for a Nigerian rural community is explored through process simulation. In this work, biogas generation from a 10.33MT/day cattle market waste was fed into a 72kWe CAT internal combustion engine and the model has been developed using Aspen HYSYS R process simulator. Simulation results shows that about 191.63MT per annum of tomato can be dried with the recovered heat while heat recovery for anaerobic digestion and drying of agricultural products increases the system's heat efficiency from 25.6% to 58.4%. The results also show that, with the current electricity tariffs for remote areas being charged at USD 0.02/kWh and Feed-in Tariffs (FITs), NPV is positive and the payback period is 3.2 years. However, system less than 1MW is not currently captured in Nigeria's FITs system while the economic indices are negative without FITs. Effects of interest rate regimes on economic indices is also explored as such system could be farm based and entitled to loan from the Nigerian Agricultural Development Bank, Bank of Industry and Commercial banks with interest rates 7%, 9% and 20% respectively. The results presented in this paper increased research knowledge on application of biogas CHP in Nigerian rural communities especially on integration of energy generation with processing of agricultural products
Techno-economic aspects of electricity generation from a farm based biogas plant
Journal of Sustainable Development of Energy, Water and Environment Systems
This study produces a technical and economic analysis of a farm-fed biogas plant that utilizes cow manure to produce electricity and heat via combined heat and power unit. The electricity generated is directly injected into the grid while heat is used within the biogas plant. The biogas system design was done depending on number of cows in the farm, which denotes the amount of manure available as feedstock. The economic performance of the proposed biogas plant was evaluated using various economic indicators. The levelized cost of electricity and the avoided greenhouse gas emissions were calculated too. The preliminary design and economic feasibility results proved the profitability of the manure-based biogas systems on wide range of farm sizes. The net present values of a 100-cow, 500-cow, 1000-cow, 1500-cow and 2000-cow farms were all positive. The internal rate of return values were 11%, 12%, 13%, 16% and 17% respectively, and the levelized cost of electricity values were 0.071, 0.069, 0.064, 0.055 and 0.055 JOD/kWh respectively. The study also produced a design for a centralized anaerobic digestion plant depending on Jordan resources. The government role in promoting biogas-based electricity was discussed too.
Evaluation of the Feasibility of Biogas-to-Electricity Plant in Maiduguri, Borno State, Nigeria
2020
There are concerns over inadequate supply of electricity to the local populace of Nigeria. Constantly increasing population has led to a wider gap between supply and demand of energy, leading to the privatisation of the power sector. Fluctuating fossil fuel prices has further increased the need to assess the available renewable energy (RE) resources. Municipal solid waste (MSW) is generally accepted to be a RE resource with wide availability, however, it has not been harnessed in Nigeria. This work will present an economic evaluation of the feasibility of investing in biogas-toelectricity projects that can process MSW generated in Maiduguri and its environments, thereby improving the supply of electricity within the city. The assessment will be carried out for energy generation by a biochemical process (Anaerobic Digestion) based on Primary and secondary data. It will also incorporate all the plants’ output (digestate, recyclables, electricity and heat) as co-products which can be m...
Overview of holistic application of biogas for small scale farmers in Sub-Saharan Africa
Biomass and Bioenergy, 2014
Holistic farming systems provide designs for the whole farm that make long term sustainable use of nutrients, water, labour, finances and energy. In using organic residues to produce energy, and safely recycling the digested residues back into the farming system, a biogas digester could be a central component of many holistic systems. This paper discusses the influence of environmental, socioeconomic and cultural constraints on the use of biogas digesters in holistic farming systems in Sub-Saharan Africa. In higher altitude areas where maintenance of optimal temperature can constrain anaerobic digestion, floating drum or fixed dome digesters are a better option than flexible balloon digesters because they are less susceptible to temperature changes. If water is a key constraint, rainwater harvesting could be used to reduce the additional labour needed to collect water. If energy is the most limiting resource in the farming system, the optimum use of organic residues might be as a fuel for anaerobic digestion, whereas, if water is limiting, energy production by burning or pyrolysis might be a better option. The bioslurry from anaerobic digestion can be used in fish ponds to produce plankton to feed fish, and can be applied to fertile fields and fields of intermediate fertility, while biochar from pyrolysis is better used to improve the soil in infertile fields. If labour is limiting, it is particularly important that the system design minimises any additional labour needed to process the organic residues on a daily basis, considering trade-offs between labour and other resources.
Access to energy is said to be an unavoidable prerequisite to sustainable development and economic growth of any nation. However, Nigeria, like any other African country, has a potential for growth in energy demand driven by population growth, yet, about 60 per cent of Nigeria's population has no access to electricity (90 per cent in rural areas). However, the population growth has also resulted in a significant increase of uncontrolled amount of waste, thus, creating environmental, social and economic problems that need urgent attention (Gajibo, 2016).
Biogas: An Alternative Energy Source for Domestic and Small-Scale Industrial Use in Nigeria
American Journal of Innovation in Science and Engineering
In Nigeria today, there is a lot of waste that is being generated on a daily basis. From Domestic wastes to kitchen wastes, poultry and livestock not excluded. Due to the current energy crisis and climate change, the country could benefit greatly from an alternative energy source which is eco-friendly, renewable, sustainable and efficient. This alternative energy source is called ‘’Biogas”. Biogas is formed by anaerobic digestion of organic materials. Biogas can be produced from kitchen wastes, cow dungs, poultry, pig faeces, etc. These wastes from the Bio-digester can later be treated as a by-product to give a nutrient rich organic fertilizer that can be used in farmlands and gardens. This paper outlines the benefits of organic waste and its potentials for domestic as well as industrial use when compared to other conventional fuels. The selected organic wastes that were thoroughly analyzed in this research work are; Human excreta, Pig excreta, sheep and goat excreta, abattoir waste...
International Journal of Global Energy Issues, 2018
Energy is an important resource in the development of any nation. Nigeria's energy demand has been epileptic in the past 50 years with frequent power outages and low availability of fuel for domestic purposes. The environmental issues associated with the consumption of fossil fuels with a growing economy have resulted in an increase in bio-waste generated. The average Nigerian makes 450−650withanaverageof450-650 with an average of 450−650withanaverageof10 on energy consumption for domestic use. 60% of these homes own a greater number of domestic animals and farm wastes. The study evaluates the potential of biogas utilisation in rural Nigeria, the acceptance of this technology and the economic viability of this technology. An analysis conducted on a 3 m 2 biogas digester estimated to cost 500withaninternalrateofreturnof23500 with an internal rate of return of 23% and a NPV of 500withaninternalrateofreturnof23232. The study shows that this technology can adequately substitute for burning firewood and also lead to a reduction in environmental pollution.