Researchers at the Zurich University of Applied Sciences have analyzed the life cycle environmental impact of the world’s first high-altitude floating PV system and have found it has an energy payback time of just 2.8 years.
The 448 kW system was built in 2019 by Swiss energy provider Romande Energie on the surface of Lac des Toules, a reservoir located at an altitude of 1,810 meters in the Swiss Alps.
“The installation consists of 35 platforms equipped with bifacial PV panels and measures a total size of 2′240 m2, covering 2 % of the lake surface,” the scientists stressed. “The structure is anchored at the bottom of the reservoir. Between mid-June and mid-December, the installation is afloat, and for the rest of the year it is posed on a platform on the ground of the reservoir.”
They also explained that their LCA assessment took into account all processes from the extraction of raw materials used for the construction of the system to its end of life. They then compared the environmental performance of the installation to lowland as well as conventional systems, under four scenarios.
“Primary data was provided by the energy company concerned and includes data for all life cycle stages of the high-altitude FPV installation,” they further explained. “Secondary data was collected through literature, with a focus on the methodology guidelines by the International Energy Agency (IEA) and Product Environmental Footprint Category Rules (PEFCR).”
The analysis showed that the high-altitude floating array emits around 94 g CO2-eq per kWh of produced electricity across its entire life cycle. The system was also found to have lower impacts on the environment compared to the other system typologies due to higher energy yield and reduced land use.
Its “environmentally intensive” mounting systems, however, were identified as a critical element increasing the installation’s environmental impact. These mounting systems require more elaborate foundations and are preferably dual-piled, which implies a higher use of aluminum, which can be up to eight times higher than in ground-mounted PV facilities.
Furthermore, the scientists stressed that reducing aluminum in the mounting system would not have only environmental benefits, but would also contribute to reducing the costs of the floating PV installation. “This can either be done by reducing general amounts of aluminum, focusing on the use of recycled aluminum or replacing aluminum with an alternative material,” they added.
The analysis also showed that the Alpine installation showed lower impacts for six out of the twelve analyzed categories and higher impacts for the other six categories, “The non-renewable primary energy demand amounts to 10′810 kWh oil-eq/kWp, which equals an energy payback time of 2.8 years,” the researchers stated.
Their findings can be found in the paper “Are alpine floatovoltaics the way Forward? Life-Cycle environmental impacts and energy payback time of the Worlds’ first High-Altitude floating solar power plant,” published in Sustainable Energy Technologies and Assessments.
“The present study adds to the scarce knowledge regarding the environmental performance of FPV systems and gives an insight into the environmental impacts of such installations at high altitudes,” the scientists concluded. “The study thereby identifies leading points for the improvement of environmental performance while highlighting the potential that this technology holds.”
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