By Barnaby Dye, FutureDAMS Research Associate

A recent study financed by the World Bank suggests that low-cost floating solar panels could produce an equivalent amount of power at a fraction of the footprint of a large dam’s reservoir.

Many developing countries have jumped stages of technology. In countries like Bangladesh, mobile phones have proliferated where landlines never spread beyond large cities. Likewise, the laptop has increased access to computing far more than desktops ever did. Is it possible that solar could do the same for large hydroelectric dams?

Hydropower has long been controversial due to its huge investment cost and the potential social and environmental impacts. It is supported by governments primarily to significantly increase electricity generation in a single investment, but often fought against by displaced people and environmentalists. One of its major drawbacks is the large area of often fertile land flooded by the dam reservoir and the villagers displaced. Alternatives that can deliver the electricity governments and citizens want are therefore in high demand.

A new report by the World Bank suggests that solar panels designed to float on water could generate more electricity than large hydropower dams. Floating solar could cover parts of dams’ reservoirs, increasing electricity generation potential and reducing evaporation. Siting solar panels on hydropower reservoirs uses the existing transmission lines and can also take advantage of a dam’s capacity to store unused solar energy, providing opportunities for pumped storage.

A dam and solar panels could function in tandem to deliver power whether the sun is shining or not. This function is significant as battery technology is still lagging behind the development of solar panels, meaning that, at present, solar power plants tend to produce power variably, in line with the intensity of sunlight.

A significant table in the report also raises further questions. It indicates that solar panels could produce the same amount of power as notable large dams at just a fraction of the physical footprint. In fact they suggest that only 1-3% of the reservoir would need to be covered by solar panels to equal the energy generation of the dam.

This list includes historically contentious projects like the Akosombo (Lake Volta) and Narmada Dams whose reservoirs have displaced tens of thousands of people. Perhaps the most significant aspect is that energy supplies for daytime consumption could be multiplied by 25-100 times in these cases, without any additional land take. Solar would not have to occupy valuable agricultural land, affect forests or grazing lands or displace additional communities .

Even if solar panels can only function during the day, and alternatives such as hydropower will be needed for night-time supply, the report notes the rapidly decreasing costs of solar panels that challenges the economic justification for new large hydropower dams and offers further evidence to allow countries to leapfrog due to the rapid technological changes happening in the energy sector.


Note:  This article gives the views of the author/academic featured and does not represent the views of FutureDAMS as a whole.

Photo by Samuel Zeller on Unsplash

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