Blue Energy from Southern African Water Bodies : State -of-the-art, Challenges and Opportunities

— In Southern Africa, the energy sector is characterised by the extensive use of coal fired power plant as well as fossil fuels. This causes environmental pollution and increased greenhouse gas emissions thereby contributing to global warming. Although solar and wind energy have emerged as major contributors to the renewable energy mix in Southern Africa, it is still necessary to diversify energy sources, with emphasis on those offering advantages beyond efficiency and renewability. Salinity gradient energy (SGE) or blue energy is one such form. Blue energy of which reverse electrodialysis (RED) represents the most attractive form is a type of marine or oceanic energy generated by mixing two water streams of different salinities. It involves the use of ion exchange membranes in an electrochemical process. The aim of the present article is to evaluate progress made in Southern Africa in the production of electricity by reverse electrodialysis. After providing some background information on RED, challenges and opportunities associated with future electricity generation in Southern Africa by RED at industrial scale were also examined. The findings revealed the inexistence of a single RED-based power plant in Southern Africa. However, it is important to mention the huge potential in blue energy provided by the numerous rivers, streams, lakes and oceans found in this region. It is concluded that future studies should focus on applying the technology to the region by training a critical mass of local researchers, a more accurate evaluation of the potential of each country to use blue energy and innovation related to the use of blue power as well as the socio-economic evaluation of integrating electricity production with some processes such as wastewater treatment, desalination and sodium hydroxide production.