Integrated AHP-TOPSIS under a Fuzzy Environment for the Selection of Waste-To-Energy Technologies in Ghana: A Performance Analysis and Socio-Enviro-Economic Feasibility Study

Energy recovery from waste presents a promising alternative for several countries, including Ghana, which has struggled with unsustainable waste treatment methods and an inadequate power supply for several decades. The current study adopts a comprehensive multi-criteria decision-making approach for the selection of an optimal waste-to-energy (WtE) technology for implementation in Ghana. Four WtE technologies are evaluated against twelve selection criteria. An integrated AHP-fuzzy TOPSIS method is applied to estimate the criteria’s weights and rank the WtE alternatives. From the AHP results, technical criteria obtained the highest priority weight, while social criteria emerged as the least important in the selection process. The overall ranking order of WtE technologies obtained by fuzzy TOPSIS is as follows: anaerobic digestion > gasification > pyrolysis > plasma gasification. The sensitivity analysis indicates highly consistent and sturdy results regarding the optimal selection. This study recommends adopting a hybrid system of anaerobic digestion and gasification technologies, as this offers a well-balanced system under all of the evaluation criteria compared to the standalone systems. The results of the current study may help the government of Ghana and other prospective investors select a suitable WtE technology, and could serve as an index system for future WtE research in Ghana. © 2022 by the authors.Cardiff University; School of Psychology, Cardiff University; School of Chemistry, Cardiff Universit

Observed controls on resilience of groundwater to climate variability in sub-Saharan Africa

Groundwater in sub-Saharan Africa supports livelihoods and poverty alleviation1,2, maintains vital ecosystems, and strongly influences terrestrial water and energy budgets. Yet the hydrological processes that govern groundwater recharge and sustainability—and their sensitivity to climatic variability—are poorly constrained4. Given the absence of firm observational constraints, it remains to be seen whether model-based projections of decreased water resources in dry parts of the region4 are justified. Here we show, through analysis of multidecadal groundwater hydrographs across sub-Saharan Africa, that levels of aridity dictate the predominant recharge processes, whereas local hydrogeology influences the type and sensitivity of precipitation–recharge relationships. Recharge in some humid locations varies by as little as five per cent (by coefficient of variation) across a wide range of annual precipitation values. Other regions, by contrast, show roughly linear precipitation–recharge relationships, with precipitation thresholds (of roughly ten millimetres or less per day) governing the initiation of recharge. These thresholds tend to rise as aridity increases, and recharge in drylands is more episodic and increasingly dominated by focused recharge through losses from ephemeral overland flows. Extreme annual recharge is commonly associated with intense rainfall and flooding events, themselves often driven by large-scale climate controls. Intense precipitation, even during years of lower overall precipitation, produces some of the largest years of recharge in some dry subtropical locations. Our results therefore challenge the ‘high certainty’ consensus regarding decreasing water resources in such regions of sub-Saharan Africa. The potential resilience of groundwater to climate variability in many areas that is revealed by these precipitation–recharge relationships is essential for informing reliable predictions of climate-change impacts and adaptation strategies

Progress in Coastal Processes Research in Ghana

In this work, we discuss an international research program focused on coastal processes in Ghana, presently in the middle stages of development. The goal of the ONR-sponsored program is for the University of Ghana to become a regional leader that produces top-flight and internationally relevant research in coastal processes. This is accomplished by creating partnerships with a variety of US and European institutions where education and capacity-building exercises for working in coastal environments are implemented. Part of the program is focused on shallow water processes with international participants providing expertise on in-depth theoretical knowledge, numerical model development and implementation, and field observation techniques, processing, and data assimilation methods. Program activities include a series of workshops conducted in 2008 and 2009 at the University of Ghana, and the development of field capabilities to observe coastal change with in situ and remote sensing instrumentation. The coastal and marine environment of Ghana contributes significantly to the economic development and security of the country. Ghana has demarcated a 200 nautical mile EEZ within the framework of UNCLOS. This has brought vast living and non-living resources under Ghanaian jurisdiction. Furthermore, shipping traffic continues to rise and associated problems with ballast water and potential oil spill raises concern for ecosystem health. The ability to monitor the environment will contribute immensely to the management of the marine ecosystem. The coastline of Ghana measures approximately 550 km and is generally a low-lying area not exceeding 30 m above sea level. The geomorphology of the coastline varies, ranging from coastal lagoons with barrier beaches to rocky cliffs fronted by narrow beaches to a large wave-dominated deltaic system (the Volta Delta). The coastal area is also bordered by a narrow continental shelf extending outwards between 30 and 90 km. Presently, there are high rates of retreat or erosion along many sections of the coastline. Shoreline recession is driven by the interplay of several factors, as wave and tidal forcing interacts with local sediment budgets (including anthropogenic disruption of sediment supply); in many cases, these processes remain poorly understood. In some areas, erosion is undermining or threatening major coastal roadways and other infrastructure. Limited resources to mitigate this threat as well as geographical constraints make this a serious problem for local communities and commerce. Understanding the past behavior of the system and the processes that drive coastal change in Ghana are critical to forecasting changes along the coastline. The research program is specifically providing assistance in the development of predictive numerical models and observational networks to examine these and other coastal-related problems