MANY African countries are heavily dependent on hydropower to provide baseline power, which is being affected by increasingly frequent droughts. At the same time, Africa is characterised by a very high solar potential.
The installation of floating photovoltaics (FPV) in existing hydropower reservoirs however, could provide solar electricity to help compensate for hydropower production losses during dry periods. It would also reduce evaporation losses while helping to sustainably satisfy the current and future needs of the fast-growing African population.
A new study, Assessment of floating solar photovoltaic potential in existing hydropower reservoirs in Africa, published in the scientific journal Renewable Energy, provides a comprehensive analysis of the potential of FPV installations in Africa. It draws on water surface data of the largest 146 hydropower reservoirs on the continent.
In addition to the electricity production, the evaporation savings and potential extra hydroelectricity generated by these water savings are estimated at reservoir level for four different cases and two types of floating structures. The study results indicate that with a total coverage of less than 1 percent, the installed power capacity of existing hydropower plants could double and electricity output could grow by 58 percent. This would produce an additional 46.04TWh annually. In this case, the water savings could reach 743 million cubic meters a year, increasing the annual hydroelectricity generation by 170.64GWh.
Potential of hydropower in Africa is still untapped
Africa has the lowest electricity access rate in the world (54 percent), with a significantly lower access rate in Sub-Saharan African (47.7 percent) compared to North Africa (96.5 percent). Concurrently, it has an annual population growth of 2.7 percent, significantly higher than South Asia (1.2 percent) or Latin America (0.9 percent). These figures illustrate the urgent need for a new deployment of power infrastructure in Africa, hence this study.
Hydropower is an especially important source of electricity in eastern and southern Africa. Of the electricity generated in Ethiopia, Malawi, Mozambique, Namibia and Zambia, 90 percent comes from hydropower.
Africa is the continent with the highest untapped technical hydropower, but according to the International Hydropower Association, only 11 percent of the total technical potential has been developed. Considering the increasing energy needs in Africa, the study presents the feasibility of an effective energy symbiosis between solar PV and hydropower through the development of floating PV systems.
The study shows the FPV systems could rapidly ramp up installed power capacities through existing infrastructure and local expertise. The FPV could also partially compensate for the reduction of hydropower output during dry periods and reduce water loss from evaporation.
Diversifying electricity sources with floating solar PV could be climate friendly
The study authors point out an additional option for the hydropower and solar energy symbiosis is the installation of PV on the face of existing dams, which can be used in parallel with FPV to further increase clean electricity generation. An earlier analysis by the authors which focused on South Africa showed that the selection of prime locations for PV systems on the face of dams can be particularly advantageous and cost-effective.
As an immature, albeit fast-growing technology, FPV presents several challenges that still need further investigation. The study flags, for example, unknown environmental issues such as algae growth, impact on the local fish food chain, ecosystem adaptation to changes in the water temperatures. Also potentially issues to address are technical challenges such as bird fouling, electrical insulation, corrosion mechanical wearing and anchoring and mooring systems.
Still, the report authors point out the excellent solar potential in Africa means the diversification of the continent’s energy portfolio is feasible. ‘The introduction of FPV in the existing hydropower reservoirs can reduce risk and support the provision of reliable power services. This increases Africa’s resilient to climate change and its ability to respond to extreme events without taking hard measure and/or redesigning existing infrastructure.’