Trygve Christiansen explores floating solar energy, a photovoltaic system powered on water. He believes floating solar panels can play an important global role in the transition to greener technologies. He is professor of marine technologies at NTNU.

“By covering 5 to 10 percent of the world’s hydroelectric power plants with floating solar power, we can generate as much electricity as the entire hydropower industry currently produces,” he says.

This will also limit evaporation from these reservoirs.

“In areas where water is a scarce resource, less evaporation is good,” says the professor, who is also president of SFI Blues, a research innovation center focused on developing and improving the next generation of floating structures. ocean industry.

Floating photovoltaic installations are now seen as a huge opportunity to provide clean electricity to large cities, especially in Asia. Solar roofs are not enough to meet demand.

“Many of the largest cities are located by the sea and floating solar installations can develop here. In addition to the large surfaces, the sea offers a significant cooling effect,” says Christiansen.

Ocean space use

Trygve Christiansen believes we don’t need to stop here. Floating solar energy can be used much more widely than just hydroelectric power plants.

“If you look at the world’s expected total energy needs in 2050, we can be even more ambitious. We calculated that if you put solar islands in 0.17% of the world’s oceans, the entire world’s electricity needs would be met,” says Christiansen.

This 0.17% of the ocean area is roughly twice the land area of ​​Norway.

“I can also imagine these solar islands becoming charging stations for ships. “They can also be used to generate electricity for floating facilities that produce renewable fuels such as hydrogen or methanol.”

Christiansen co-authored a magazine article on the subject. PNAS (Proceedings of the National Academy of Sciences) in 2019.

Floating solar works best where weather conditions are calmer

“The ocean is big,” Christiansen says. At any given moment, 173,000 terawatts are constantly shining from the sun to Earth, radiating 10,000 times more energy than we can use. Credit: NASA

However, not all ocean areas are suitable for the development of floating solar energy.

“Placing floating solar panels where the weather is calmest, windy and choppy is definitely an advantage. In Doldrums, a belt around the Earth near the equator, there is little wind and the sun shines directly down, so these places are well located. for floating solar cells. Likewise, there are places where the waves are, not the waves,” says Christiansen.

The floating sun competes with the offshore wind.

“If you cover a square kilometer with solar panels in southern Spain, where the average annual solar radiation is 200 watts per square meter, floating solar can generate about 44 megawatts. Modern wind turbines produce an average of 6 megawatts for this.” oblast says.

How do solar photovoltaic devices float?

We haven’t yet determined the best technology for this approach. A floating solar cell should be cost effective. At the same time, sunny islands have to withstand small waves and strong winds. Floating structures must follow the waves to work.

Christiansen identifies two main concepts of floating solar energy.

• One option consists of floating membranes attached to movable collars. The Norwegian company OceanSun has already installed several full-scale membrane systems.
• The second concept consists of smaller, solid modules interconnected in large matrices. Several companies are offering different versions of this system, including Equinor and Moss Maritime, which tested a floating prototype off the island of Frøya.

“Other concepts are also possible, such as air cushion structures and flexible pipes interconnected in different configurations,” Christiansen said.

Floating solar energy is a fairly new concept

Several pilot floating solar power plants have already been built around the world. They can often be found in reservoirs, cities, and communities on islands where there are no other energy sources. Floating solar panels are being installed at several hydroelectric power stations in Japan and China.

“We also need this capacity in Norway, for example to power on-site aquaculture facilities or to power Norway’s new energy-intensive industries, such as battery factories,” he said.

The idea of ​​expanding solar panels to floating structures in dams and other land-based water sources and the ocean is relatively new.

“Floating solar is an area of ​​research that is in its very early stages. However, in the last two years, it has started to attract attention. Last year, the EU announced tenders for research projects,” he said.