Floating solar panels, touted for their energy efficiency and reduced environmental impact, could actually increase greenhouse gas emissions in certain aquatic ecosystems.
Floating solar power: a miracle solution?
Let’s start this paper with a little definition! A floating solar panel is a photovoltaic system installed directly on a water surface such as a lake, reservoir or pond. This technology saves valuable land space while benefiting from natural cooling, which improves the panels’ performance. In addition, floating solar panels can reduce water evaporation and help preserve water quality. As stated in the title, on paper this system seems to be highly advantageous in many respects.
In recent years, floating solar panels have emerged as a promising alternative for generating electricity without encroaching on farmland. They can be found on canals in India, water reservoirs in Switzerland and marshes in Spain. As well as producing energy, they offer collateral benefits, such as reducing water evaporation in regions affected by drought.
But while this technology seemed to have nothing but advantages, a recent study has thrown a spanner in the works. Researchers at Cornell University have examined the environmental impact of floating solar panels on small bodies of water… and their findings are surprising.
An increase in greenhouse gases
The main finding of this study is that covering ponds or lagoons with solar panels could increase greenhouse gas emissions rather than reduce them. How is this done? We’ll explain.
To achieve this result, the researchers installed panels on three experimental ponds at the Cornell Experimental Pond Facility. 70% of their surface was covered, while other similar ponds were left untouched, serving as a control group. After several months of observation, the researchers measured the differences between the ponds and found that the water bodies covered with solar panels had significantly higher levels of dissolved methane and carbon dioxide. Here are some key figures to bring out at family dinners:
- Greenhouse gas emissions increased by 27% compared with ponds without panels.
- The amount of dissolved oxygen fell, impacting aquatic life.
- The decomposition of organic matter and microbial activity were disrupted.
In short, floating solar panels are changing the ecological balance of small bodies of water, which could have significant consequences for these fragile ecosystems.
A mixed environmental record
However, these results need to be put into perspective. If we compare the overall carbon footprint of floating solar energy to fossil fuels, it remains largely favourable. But this study highlights a crucial point: we are not yet fully measuring the impact of these new technologies on certain ecosystems. Not to mention, of course, all the criticisms that have already been levelled at solar energy: it is intermittent, so batteries are needed, and building a solar panel requires a lot of CO2, and so on.
Floating solar panels shouldn’t be completely discarded, of course, but their installation needs to be considered on a case-by-case basis. The fashion of the moment must not override everything. Large artificial reservoirs and canals seem ideal candidates, while small natural ponds should be protected. The energy transition is underway, but it needs to be done intelligently to limit its side-effects on the environment.
I’m guessing it is the reduction of photosynthesising algae under the deep shade of the solar panels which is the main cause because the depletion of oxygen there means that more anaerobic bacteria can grow which give off CH4 as their waste product.
One way to mitigate this might be to use some of the electricity from the solar cells to drive some aeration systems around the edges of the solar arrays and some propellers to make the water circulate around the whole water body.