Geospatial multi-criteria analysis for identifying optimum wind and solar sites in Africa: Towards effective power sector decarbonization
Introduction
The population of Africa is expected to double by 2050, reaching an estimated 2.4 billion in a world where population growth is declining [1]. Predicted to be the fastest urbanizing region in the world, the continent is expected to witness more than 80% of its population growth to occur in cities over the next two decades [2]. This population boom in the burgeoning cities of Africa is foreseen to have significant economic repercussions that would entail profound changes in energy demand. The current lion's share of the electricity generation in Africa comes from fossil fuel (40% Natural gas, 30% Coal and 9% Oil), which makes up 79% of the centralized electricity grid, with a generation potential of 870 TWh [3]. While electricity access in Northern Africa reaches nearly 99% of the population, primarily generated from oil and gas, Sub-Saharan Africa (excluding South Africa) has an electricity access of about 29%, more than half of which is generated from hydropower [4]. South Africa, on the other hand, has an electricity access of 77%, and is heavily reliant on coal [4,5]. In 2018, renewable energy generation capacity in Africa stood at about 50 GW, primarily derived from hydropower (35 GW), wind (5.5 GW), solar PV (4.5 GW) and geothermal (0.7 GW) [3]. However, as stated by Rodriguez-Manotas et al. [6], several East African countries which are heavily reliant on hydro for electricity generation, are shifting towards other renewable energy sources due to the depletion of water resources and successive droughts. The IRENA [7] reported global weighted average cost reductions of 69% in the electricity generation of utility-scale solar PV plants and 18% for onshore wind electricity generation between 2010 and 2016. Hence onshore wind and solar PV represent viable alternatives that can ensure a cost-effective and economically robust, continent-wide energy transition.
Power sector reform is much needed in Africa since, on the one hand, over-reliance on fossil fuel imports has economic repercussions on net-importing countries caused by fossil fuel price fluctuations on international markets, while on the other hand, economies dependent on fossil fuel exports are subject to increased fiscal pressures caused by dwindling export revenues [8,9]. Consequently, diversification of the energy mix is an important step in achieving energy security and ensuring an economically robust energy transition. The long-term international goal of net zero emissions will rely on major renewable energy investments to replace fossil fuels. Even in the medium term, several African countries aim to meet their emission reduction targets by transforming their carbon-intensive power sectors to low carbon energy systems [10]. However, the costs of renewable energy are spatially variable for a range of geographical, environmental, economic and political reasons. In this context, it is important that renewable energy investments are made at spatially appropriate sites. The last decade has seen the tripling of international investments channeled to the energy sector in the continent, attaining $8 billion in 2015 [11]. The main investor over the 2005–2015 period was the World Bank Group with a financial assistance of $17.6 billion, primarily in fossil fuel energy (notably coal) where its contribution was more pronounced in both Sub-Saharan Africa and South Africa. The European Union on the other hand invested $16.8 billion, mainly in hydroelectricity, solar and wind, predominantly in North Africa. A quarter of the investments over the period 2005–2015 came from the African Development Bank with a share of $14.4 billion, mostly in electricity distribution infrastructures [11]. Africa was the recipient of the highest spatial density of the climate funds, with South Africa having the largest number of investments over the 2013–2016 period in the continent [12].
However, as stated by the Africa Progress Panel [13], excessive fragmentation coupled with poor coordination are major roadblocks in ensuring efficient investments in the African power sector. Investments made by the European Union in the continent has been distinctly uncoordinated with 26 different initiatives coming from member states and institutions [14]. Such a fragmented system results in efficiencies and overlaps in the investment process. Consequently, coordination among the donors and knowledge of where to invest in order to make a significant impact, are crucial. Numerous market barriers exist in Africa which tend to dampen the attractiveness of investments across the continent. Some countries have started to establish adequate policy and regulatory frameworks to spur renewable energy growth and address these investment barriers.
This paper seeks to geolocate the potential of the African continent for utility-scale, grid-connected solar PV and onshore wind farms. As indicated by Gies [15] despite the fact that Egypt, Ethiopia, Kenya, Morocco and South Africa are driving renewable energy development, a significant barrier to project implementation in the African continent is the unavailability of high-resolution wind and solar resource potential maps that would allow investors to make informed decisions pertaining to investments. Consequently, it would be useful to develop a high-resolution mapping of the solar and wind resource potentials in Africa in order to bridge this knowledge gap and attract investments for utility-scale solar and wind energy projects at spatially optimum sites to help avert a fossil fuel lock-in.
Determination of optimum sites for utility-scale wind and solar farm installations necessitates the integration of multiple factors that affect the costs of both generation and the transfer of electricity to users, whilst meeting legal requirements [16]. Consequently, in this paper, we use Multi-Criteria Decision Analysis (MCDA) coupled with GIS, to incorporate environmental, economic, legal, social and technical criteria, in order to determine spatially optimum sites for utility-scale wind and solar installations. The objective of the analysis is to identify countries having abundant solar and wind resources and which rely heavily on fossil fuel electricity, which should be priorities for investments in utility-scale wind and solar so as to phase out fossil fuel reliance.
Regional studies from different areas in Africa using the MCDA GIS-based approach have mainly focused on revealing the technical potential for wind and solar installations. In the tropical savanna climate of Mauritius, Doorga et al. [17] identified optimum sites for solar farms using a multi-criteria model consisting of climatological, topographic and economic-based factors. In the Mediterranean climate of Southern Morocco, Mensour et al. [18] implemented a multi-criteria model, incorporating climatological, environmental, topographic and economic-based factors to locate ideal sites for solar farm placements. Hamid [19], on the other hand, explored the wind energy potential in the desert climate of Egypt using a multi-criteria model comprising of climatological, environmental, topographic and economic-based factors. In the oceanic subtropical highland climate of the Amhara Region in Ethiopia, Dereje [20] identified ideal sites for wind farm placements using a multi-criteria model consisting of climatological, social, environmental, topographic and economic-based factors. However, while regional, meso-scale multi-criterial studies tend to involve limited factors for optimum wind and solar site identifications, a continent-wide, macro-scale analysis would require the scope to be broadened in order to account for political and investment risk factors which dictate renewable energy investments. However, there is no comparable analysis at the continental scale.
The geographical limitations of previous resource assessment studies are mainly due to the lack of high-density and temporally consistent long-term in-situ measurements, particularly in sub-Saharan Africa, which pose a major problem to conduct a geospatial analysis at the continental level [21]. However, the recent availability of high-resolution and continent-wide solar and wind datasets recorded by METEOSAT satellite has enabled us to conduct a continent-wide analysis. Moreover, besides the larger-scale analysis, the proposed multi-criteria analysis is the first to integrate political and institutional factors to reflect the variations in prevailing politico-institutional regimes across Africa. Investors rank political concern as the major factor influencing investments while an adequate institutional structure comprising of an established supply chain, expertise and attractive policy landscape influence the rate of renewable energy investments [22]. The importance of the current study is that it will provide knowledge of where investments in renewables should be taking place in Africa, to assist investors in making informed decisions for effective power sector decarbonization.
Section snippets
Framework overview
The methodological framework is shown in Fig. 1. Initially, a macro-level analysis is performed to identify the countries having high wind and solar energy investment potentials. Consequently, a wind/solar potential model is implemented, integrating factors found to influence the placements of wind and solar farms (influential factors). Weights are allocated to each influential factor based on its degree of influence. The weighted factors are thereafter combined and infeasible areas (spatial
Utility-scale solar PV
Factors influencing the placement of solar farms, as described in section 2.5.1, are mapped and illustrated in Fig. 4. The solar potential model aims at identifying countries that have abundant solar resources, rely heavily on fossil fuel for electricity generation, and are politically stable so that investments would offer the highest electricity decarbonization potentials. An important stage in the multi-criteria analysis process prior to combining the different factors, is the rescaling of
Discussions
Through the multi-criteria GIS-based technique, multiple variables that influence the investment decisions can be integrated to optimize solar and wind farm placements. The continental-scale analysis revealed that Egypt displays high solar farm investment potential to achieve significant power sector decarbonization, owing to its favorable insolation (278.3 W/m2), high fossil fuel electricity dependence (165.7 billion kWh), political stability and other suitable investment factors. Natural gas
Conclusions
A multi-criteria model has been implemented using a set of climatological, political, environmental, technical and socio-economic factors to determine optimum sites in Africa where wind and solar farm investments could have the most impact in decarbonizing the power sector. The methodology is novel in that it takes into account the geospatial variations in political and institutional regimes across the continent that influence utility-scale renewable energy investments.
The analyses revealed
Credit author statement
All authors contributed equally to this work.
Data availability
The datasets generated and analyzed during the current study are available from the corresponding author on reasonable request.
Declaration of competing interest
On behalf of all authors, the corresponding author states that there is no conflict of interest.
Acknowledgements
The research described in this paper has been funded by the University of Oxford through the Oxford ECM Dissertation Award. We are grateful to the World Bank, IRENA, OpenStreetMap, NOAA, CMSAF, WorldClim, OECD, NASA, WWF, EIA, SDG, WFP, Natural Earth, RCMRD Geoportal, Department of Environmental Affairs of South Africa, Worldpop and Protected Planet for the provision of data. We also acknowledge BPMSG and NREL for facilitating criteria weight and LCOE computations, respectively.
References (71)
- et al.
Sustainable energy in Africa: a comprehensive data and policies review
Renew Sustain Energy Rev
(2014 Sep 1) - et al.
Getting on the ground: exploring the determinants of utility-scale solar PV in Rwanda
Energy Res Social Sci
(2018 Aug 1) - et al.
Enabling solar photovoltaics penetration in highly dependent African fossil fuel markets
- et al.
A risk-based multi-criteria spatial decision analysis for solar power plant site selection in different climates: a case study in Iran
Renew Energy
(2019 Dec 1) - et al.
Multi-criteria GIS-based modelling technique for identifying potential solar farm sites: a case study in Mauritius
Renew Energy
(2019 Apr 1) - et al.
A geographical information system-based multi-criteria method for the evaluation of solar farms locations: a case study in Souss-Massa area, southern Morocco
Energy
(2019 Sep 1) - et al.
Application of analytical hierarchy process to analyze stakeholders' preferences for municipal solid waste management plans, Boston, USA
Resour Conserv Recycl
(2008 May 1) A scaling method for priorities in hierarchical structures
J Math Psychol
(1977 Jun 1)- et al.
Solar electricity prospects in Oman using GIS-based solar radiation maps
Renew Sustain Energy Rev
(2010 Feb 1) - et al.
Global available wind energy with physical and energy return on investment constraints
Appl Energy
(2018 Jan 1)