According to a new study, floating solar farms could help protect reservoirs and lakes from some of the adverse effects of climate change.
But considering the varying designs of solar technologies and the complex nature of water bodies, deploying floating solar arrays could also have detrimental impacts on the ecosystem.
Traditional solar farms are a debatable topic because of the amount of land taken up by them. This is creating a growing interest in the floating solar farms—leveraging the extra space provided by water bodies.
To date, three commercial-size floating solar arrays are available in the United Kingdom, and there are hundreds more worldwide. The number of installations may probably grow considerably in the years to come as demand increases for renewable energy sources with more nations pledging to net-zero carbon targets.
But not much was known about the effects—both negative and positive—of these floating solar farms installed on the reservoirs and lakes, until now.
Researchers from Lancaster University and the University of Stirling have now finished the first comprehensive modeling of the environmental impacts of floating solar installations on water bodies.
As demand for land increases, water bodies are increasingly being targeted for renewable energy. Deployment of solar on water increases electricity production, but it is critical to know if there will be any positive or negative environmental consequences.”
Mr Giles Exley, Study Lead Author and PhD Researcher, Lancaster University
“Given the relative immaturity of floating solar farms, it is important to further scientific evidence of the impacts. Our results provide initial insight of the key effects that will help inform water body manager and policymaker decisions,” Mr Exley added.
Computer modeling was performed by the researchers using the MyLake simulation program as well as data obtained by the UK’s Centre for Ecology and Hydrology from England’s largest lake in Windermere.
While the investigators believe that floating solar farms are not likely to be deployed on Windermere, it nevertheless presents a rich set of data because it is one am the most extensively investigated lakes in the world.
The team’s results demonstrate that floating solar arrays can cool the temperatures of water by screening the water from the sun.
On a larger scale, this could help reduce the dangerous impacts triggered by global warming, like blooms of poisonous blue-green algae, and the increased evaporation of water, which could pose a risk to water supply in certain areas.
The researchers further observed that the installation of floating solar also decreased the period of “stratification”—this is where the water is heated up by the sun, creating clear layers of water at varying temperatures.
This scenario tends to occur more during the warmer summer months and can cause the bottom water layer to become deoxygenated, which deteriorates the quality of water—an evident problem for drinking water supplies.
But the picture is more complicated and there are also situations under which stratification, and thus the detrimental effects of water quality, could increase if floating solar farms are installed.
The effects of floating solar on the temperature of the water body and stratification, both of which are major drivers of biological and chemical processes, could be comparable in magnitude to the changes lakes will experience with climate change. Floating solar could help to mitigate against the negative effects global warming will have on these bodies of water.
Mr Giles Exley, Study Lead Author and PhD Researcher, Lancaster University.
Mr Exley added, “However, there are also real risks of detrimental impacts, such as deoxygenation causing undesirable increases in nutrient concentrations and killing fish. We need to do more research to understand the likelihood of both positive and negative impacts.”
The impacts on the temperature of water led to larger solar installation, with tiny arrays measuring less than 10% of the lake surface that usually have minimal effects. But this model focused on a single lake.
Additional analyses will be required to establish the optimum design, size array, and their impacts for separate reservoirs and lakes—all of which have special qualities. Besides this, different designs of solar installations have different sheltering and shading effects for winds and the sun.
Arrays spanning over 90% of a lake could raise the chances of the lake freezing over in winter months, found the study—although such effects would also be specific to the water body and the installation design and will need additional analyses.
Field analyses and additional modeling work to build on these preliminary results are underway.
The study titled, “Floating photovoltaics could mitigate climate change impacts on water body temperature and stratification” has been published in the Solar Energy journal.
The authors of the study are Giles Exley, Alona Armstrong, and Trevor Page from Lancaster University, and Ian Jones from the University of Stirling.
Exley, G., et al. (2021) Floating photovoltaics could mitigate climate change impacts on water body temperature and stratification. Solar Energy. doi.org/10.1016/j.solener.2021.01.076.