Floating solar panels help conserve water, provide huge amounts of energy, and are close to consumers
Installing solar panels over a water reservoir seems like an obvious solution.
They do not reduce available agricultural land, and the cover helps keep evaporation down.
It has also been done on a smaller scale in countries such as China, France, India, Japan, South Korea, the UK, Singapore, and the USA.
But what if all major water reservoirs in the world are covered by solar panels? What would this mean for the production of green electricity?
The results have just been published by an international group of researchers in the Nature Sustainability journal.
The researchers have studied the number of reservoirs worldwide and linked it with the latest technological solutions and environmental considerations.
The model was developed by the U.S. Department of Energy, and the data comes from, among other things, two decades of satellite observation of temperatures, solar irradiation, and wind speed, according to ARSTechnica.
To account for the fact that many water reservoirs have developed their own ecosystems, the solar panel coverage was limited to 30 percent of the surface area or 30 square kilometres, whichever is lower.
Here is the potential for floating solar panels installed over existing water reservoirs across the world.
Using water reservoirs for solar panels has—in addition to reduced evaporation—several advantages:
Water reservoirs are often located close to population centres, where water is used.
Therefore, the electricity would also not have to be transported far.
If the reservoirs are covered, this could also limit algal blooms in the water.
On top of all that, many water reservoirs are part of hydropower plants, and the two electricity sources can complement each other and thus be used to create a stable electricity system.
More than 40 percent
In total, the researchers have calculated that this type of floating solar panels can produce 9,400 TWh per year.
For comparison, the global annual electricity consumption is approximately 22,800 TWh, which means that floating solar panels would theoretically be able to cover over 40 percent of the consumption.
If the surface coverage is reduced from 30 percent to 10 percent, it would still be possible to produce 4,300 TWh.
Looking at the USA alone, such floating solar panels would be able to produce 1,900 TWh or almost half of the USA’s total electricity consumption.
The researchers estimate that there are 40 countries in the world that could meet their total energy demands (i.e. not just electricity consumption) through floating solar panels. But they also emphasize that these are mainly small countries with weak economies, and that energy storage would present a problem.
The analysis also indicates that there are 150 cities with populations over a million that could be able to cover their electricity consumption exclusively through solar panels on nearby reservoirs.
But floating solar panels have a few more benefits in addition to the electricity production.
When a reservoir is covered, the evaporation of water is reduced.
Calculations show that with the aforementioned limits, an additional 100 cubic kilometres of water would be made available for use. This corresponds approximately to the water consumption of 300 million people.
A country like South Africa would be able to produce 144 TWh—out of its annual consumption of 205 TWh—and at the same time avoid losing 1.6 cubic kilometres of water to evaporation.