Floating solar panels could revolutionize renewable energy

In a recent article in Water Natureresearchers explored the global potential of floating photovoltaics (FPV), a renewable energy technology that involves installing solar panels on water surfaces. Their goal was to estimate the power output, water savings and environmental benefits of FPV in bodies of water around the world. This technology can play an important role in decarbonizing national economies and reducing water scarcity.

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Background

Photovoltaics are among the fastest growing and most cost-effective sources of renewable energy, potentially covering a significant portion of the world’s electricity demand. However, due to high temperatures, conventional photovoltaics face challenges such as land use competition, water consumption and efficiency losses.

FPV, i.e. photovoltaic systems mounted on structures floating on bodies of water, can overcome some of these limitations by using the available water surface, limiting evaporation and taking advantage of the cooling effect of water. They also offer advantages over ground-mounted solar PV in terms of installation, maintenance and operating costs, as well as social acceptance and environmental impact.

About research

In this article, the authors sought to quantify the power generation potential of FPV in over one million bodies of water around the world, including natural and artificial lakes and reservoirs larger than 0.1 square kilometers in size. They assessed the contribution of FPV to decarbonizing the energy system and managing water resources.

Data from the Global Solar Energy Estimator (GSEE) and climate inputs from the Global Climate Reanalysis were used. The study reconstructed the monthly water surface area time series for each water body from 1991 to 2020 to determine the theoretical power output of FPV vehicles.

To select suitable bodies of water for FPV deployment, researchers used several criteria, such as proximity to population centers, protection status, duration of ice cover, and water level fluctuations. They compared the potential of FPV with each country’s electricity demand, carbon intensity and access to electricity, and calculated water savings and CO emissions₂ emission reduction achievable by FPV. Additionally, they discussed the possible impact of FPV on water quality, algal blooms and freshwater ecosystems.

Key methodologies included calculating the annual power output of a 1 kW FPV system and extrapolating these results to estimate the total global potential. To determine possible locations for FPV deployment, constraints such as proximity to population centers, protection status, duration of ice cover and durability of water bodies were taken into account.

The water saving potential of FPV was assessed by assessing the reduction in evaporative losses resulting from covering the water surface with solar panels. The purpose of this study was to provide a realistic assessment of the ability of FPV vehicles to meet national electricity demand, reduce water scarcity, and contribute to decarbonization efforts.

Findings

The results highlighted the significant potential of FPV vehicles to generate renewable energy and save water. The theoretical global annual power output from FPV, assuming 10% water body coverage, was estimated at 14,906 TWh. This capacity could meet an average of 16% of electricity demand in many countries, with some countries able to meet their needs through FPV. Geographic differences were noteworthy, with regions with higher sunshine such as the western United States, the Andean Mountains, and the Qinghai-Tibet Plateau showing greater strength.

Seasonal patterns in productivity rates were evident, with significant fluctuations between summer and winter in the Northern Hemisphere.

Larger bodies of water naturally accommodate larger FPV arrays, producing higher power output. Despite restrictions limiting the number of relevant water bodies to 67,893, they could still generate a significant 1,302 TWh per year. Countries such as China, Brazil and the United States have great FPV potential due to their vast bodies of water and significant demand for electricity.

In terms of water conservation, FPVs offer significant potential to reduce evaporation from water bodies, bringing particular benefits to regions facing water scarcity. The shading effect of solar panels lowers the surface temperature of the water, resulting in a reduced evaporation rate. This advantage is essential in arid and semi-arid regions with limited water resources. For example, FPVs could meet 129% of Ethiopia’s electricity demand, 73% in Chad, 45% in Argentina and 29% in Malawi. The study also estimated that FPVs could reduce global CO emissions annually₂ emissions by 0.45 billion tons and save 62.9 km3 of water by reducing evaporation.

Apps

FPV integration has potential implications for various sectors and regions. These systems can increase the efficiency and reliability of existing hydropower plants by sharing infrastructure and offsetting seasonal variability in water availability. In addition, they offer opportunities to improve water quality and ecosystem health in water bodies.

By mitigating algal blooms, reducing nutrient concentrations and preventing thermal stratification, FPVs contribute to overall environmental sustainability and ecosystem resilience.

Application

The authors highlighted the importance of FPV in the global energy landscape. This technology can make a significant contribution to achieving renewable energy, water conservation and decarbonization goals. Future work should focus on overcoming technical hurdles, engaging with stakeholders, refining designs, establishing a resilient regulatory framework, and exploring the socio-economic consequences of widespread FPV deployment.

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