This research assesses the social impacts that could arise from the potential waste-to-energy (WtE) generation of electricity from municipal solid waste (MSW) in the cities of Lagos and Abuja in Nigeria. Social life cycle assessment (sLCA) was the main analytical approach used coupled with a participatory approach to identify relevant social issues to serve as the potential sLCA impact ‘subcategories’. Focus group research in both cities led to the identification of 11 social issues that were transformed into social impact subcategories with appropriate indicators for the sLCA. These were populated with data from a questionnaire-based survey with approximately 140 stakeholders. The results indicated that the impact subcategories “Improved Electricity Supply” and “Income” were ranked respectively as having the most and the least significant social impacts associated with the potential adoption of WtE in these two cities in Nigeria. Overall, the research showed that the expected social impact was higher for WtE electricity generation in Lagos than in Abuja. This difference may be related to the higher population and greater amounts of waste in Lagos and its position as a hub for many of the country’s commercial and industrial activities which have long been affected by inadequate electricity supply. This study also provides an example of the use of participatory processes as an important approach in sLCA for the elucidation of social issues that are directly pertinent to key local perspectives when considering such technology implementations.
Diverse opportunities and environmental impacts could occur from a potential move towards waste-to-energy (WtE) systems for electricity generation from municipal solid waste (MSW) in Lagos and Abuja, Nigeria. Given this, the purpose of this study is to use life cycle assessment (LCA) as a primary analytical approach in order to undertake a comparative analysis from an environmental impact perspective of different WtE scenarios, along with diesel backup generators (DBGs) and grid electricity. A functional unit of 1 kilowatt-hour of electricity produced was used in assessing the following environmental impact categories: abiotic depletion (fossil fuels) potential (ADP), global warming potential (GWP 100a), human toxicity potential (HTP), photochemical oxidation potential (POCP), acidification potential (AP), and eutrophication potential (EP). The overall result indicated that anaerobic digestion (AD) had the highest energy generated per one tonne of MSW processed for both Lagos (683 kWh/t) and Abuja (667 kWh/t), while landfill gas to energy (LFGTE) had the lowest for both (Lagos 171 kWh/t, Abuja 135 kWh/t). AD also had the lowest environmental impacts amongst the four WtE systems for both cities based on all the impact categories except for POCP. In contrast, LFGTE had the highest impact in all the categories except ADP and HTP. Extending the analysis to include diesel-based generators (DBG) and grid electricity saw the DBGs having the highest impact overall in ADP (14.1 MJ), HTP (0.0732 Kg, 1.4 DB eq), AP (0.0129 Kg SO2 eq), and EP (0.00313 Kg PO4 eq) and grid electricity having the lowest impact in GWP (0.497 Kg CO2 eq), AP (0.000296 Kg SO2 eq), and EP (0.000061 Kg PO4 eq). It was concluded that additional electricity supply from AD to the grid, with its potential to reduce the reliance on DBGs (worst scenario overall), would be a positive action in environmental impact terms.
Waste management and electricity supply have always been among the main challenges faced by developing countries. So far, the use of waste to energy (WtE) is one strategy that could simultaneously address these two challenges. However, the use of such technologies requires detailed studies to ensure their sustainability. In this paper, the potential of WtE in two cities in Nigeria (Abuja and Lagos) using anaerobic digestion (AD), incineration, gasification and landfill gas to energy (LFGTE), is presented with the aim of evaluating their economic viability using life cycle costing (LCC) as an analytical tool. This economic feasibility analysis includes LCC, levelised cost of electricity (LCOE), net present value (NPV), internal rate of return (IRR) and payback period. A sensitivity analysis was conducted to investigate the influence of several parameters on the economic viability of the selected technologies for the two cities. The economic assessment revealed that all the WtE systems were feasible and viable in both cities except for LFGTE in Abuja where the NPV was negative (−USD 105.42/t), and the IRR was 4.17%. Overall, incineration for both cities proved to be the most favourable economic option based on its positive LCC (Lagos USD 214.1/t Abuja USD 232.76/t), lowest LCOE (Lagos USD 0.046/t Abuja USD 0.062/t), lowest payback period (Lagos 1.6 years Abuja 2.2 years) and the highest IRR (Lagos 62.8% Abuja 45.3%). The results of the sensitivity analysis also indicated that variation in parameters such as the capital cost and discount rate have significant effects on the LCC. This paper provides information for potential investors and policy makers to enhance optimal investment in WtE technologies in Nigeria.
Globally, rising population and rapid urbanisation have resulted in the dual issues of increased electricity demand and waste generation. These exacerbate diverse global problems, ranging from irregular electricity supply and inadequate waste management systems to water/air/soil pollution, climate change, etc. Waste-to-Energy (WtE) approaches have been proposed and developed to address simultaneously these two issues through energy recovery from waste. However, the variety of available waste materials and different WtE technologies make the choice of an appropriate technology challenging for decision-makers. The evaluation of the different WtE technologies in terms of their sustainability could provide a solid comparative base for strategic decision making in the power and waste management domains. This paper presents research conducted using a multidimensional Life Cycle Sustainability Assessment (LCSA) approach to estimate and compare the environmental, economic, and social impacts associated with the generation of electricity from Municipal Solid Waste (MSW) in two major cities, Lagos and Abuja, in Nigeria. These cities provide case studies in a developing world context to explore how their similarities and differences may influence the LCSA impacts for four WtE systems (Anaerobic Digestion, Incineration, Gasification, and Landfill Gas to Energy), and this is the first research of its kind. An LCSA ranking and scoring system and a muti-attribute value theory (MAVT) multi-criteria decision analysis (MCDA) were employed to evaluate the overall sustainability of the prospective use of WtE over a 20-year timeframe. The results from both approaches indicated that the adoption of WtE offered sustainability benefits for both cities, marginally more so for Lagos than Abuja. It was concluded that, for optimal benefits to be achieved, it is vital for decision-makers to think about the various trade-offs revealed by this type of analysis and the varying priorities of relevant stakeholders.
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