It is an idea that may have found its moment. Droughts are crippling power supplies from many hydroelectric dams across Africa, with dwindling reservoirs evaporating in the hot sun. So, say researchers, why not tap that sun? Solar panels floating on the water could generate more power to deliver to the existing turbine power lines, while at the same time shading the water to reduce evaporation losses.

The Africa plan is the most dramatic example of an explosion of interest in installing floating solar panels on reservoirs and other water bodies, such as tidal flats and flooded former open-pit mines.

In January, researchers at the European Commission’s Joint Research Centre in Ispra, Italy, published a study of the huge potential for hybrid hydro-solar power plants in Africa, the sunniest continent. Lead researcher Rocio Gonzalez Sanchez reckons covering just 1% of the continent’s reservoirs could double their power generating capacity to 58 gigawatts, increasing the continent’s overall generating capacity by up to a quarter.

Some of the continent’s biggest reservoirs could benefit, including the High Aswan on the Nile in Egypt – which currently loses about a quarter of its annual water input to evaporation in the Sahara sun – the Kariba and Cahora Bassa dams on the Zambezi in southern Africa, and the Akosombo in Ghana. It would be a cheaper alternative to building new dams, Sanchez says, with none of the environmental and social downsides from flooding more land.

The panels would not float, which is made impractical by the rapid water flows down the canals. They would instead be installed on gantries or strung from suspension cables above the canals. The benefits of shade would largely remain, however. Like floating panels on reservoirs, the suspended panels would reduce evaporation from the canals and potentially also reduce weed infestation, McKuin argued in a study published in March in the journal Nature Sustainability.

Source: “Floating solar ready for take-off” China Dialogue