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Floating solar – a missing piece of the energy decarbonisation puzzle?

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Floating solar panels (FPV) could supply all the electricity needs of some countries, according to new research.

There are currently very few FPV installations in the UK, with the largest a 6.3 MW floating solar farm on the Queen Elizabeth II reservoir, near London. However, there is still potential to produce an additional 2.7 TWh of electricity each year which would provide electricity for around one million homes, based on the current Ofgem estimate of average electricity usage per household of 2,700 kWh.

The study by researchers from Bangor and Lancaster Universities plus the UK Centre for Ecology & Hydrology, aimed to calculate the global potential for deploying low-carbon floating solar arrays. The researchers calculated the daily electrical output for FPV on nearly 68,000 lakes and reservoirs around the world, using available climate data for each location.

The researchers’ calculations included lakes and reservoirs where floating solar panels are most likely to be installed, based on the technology covering just 10% of their surface area, up to a maximum of 30km2. They were no more than 10km from a population centre, not in a protected area, didn’t dry up and didn’t freeze for more than six months each year. 

While output fluctuated depending on altitude, latitude and season, the potential annual electricity generation from FPV on these lakes was 1302 terawatt hours (TWh), around four times the total annual electricity demand of the UK.

The figures were considered country-by-country and the report highlighted five nations could meet their entire electricity needs from FPV, including Papua New Guinea, Ethiopia and Rwanda. Others, such as Bolivia and Tonga, would come very close, respectively meeting 87% and 92% of electricity demand.

Many countries, mainly from Africa, the Caribbean, South America and Central Asia, could meet between 40% and 70% of their annual electricity demand through FPV. In Europe, Finland could meet 17% of its electricity demand from FPV and Denmark, 7%.

The research highlighted a number of advantages the floating systems have over land-based solar installations, including their ability to free up land for other uses such as farming and keep panels cooler, making them more efficient.

There is also evidence for other environmental benefits, including reducing water loss through evaporation, by sheltering the lake surface from the sun and wind; and reducing algal blooms by limiting light and preventing nutrient circulation. However, the researchers warn that further research is needed on the overall environmental impact of FPV. They suggest that decisions to deploy FPV should consider the intended function of water bodies and how they are used, as well as the potential ecological impact.

Lead author of the paper, Dr Iestyn Woolway of Bangor University said;

“We still don’t know exactly how floating panels might affect the ecosystem within a natural lake, in different conditions and locations. But the potential gain in energy generation from FPV is clear, so we need to put that research in place so this technology can be safely adopted. We chose 10% of a lake’s surface area as a likely safe level of deployment, but that might need to be reduced in some situations, or could be higher in others.

“Even with the criteria we set to create a realistic scenario for deployment of FPV, there are benefits across the board, mainly in lower income countries with high levels of sunshine, but also in Northern European countries as well. The criteria we chose were based on obvious exclusions, such as lakes in protected areas, but also on what might reduce the cost and risks of deployment.”

Co-author Professor Alona Armstrong of Lancaster University said;

“Our work shows there is much potential for FPV around the world. But deployments need to be strategic, considering the consequences for energy security, nature and society, as well as Net Zero.”

The ‘Decarbonisation potential of floating solar photovoltaics on lakes worldwide’ research paper is available to read in full here.

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