Floating Photovoltaics with Fishing Current Scientific Evaluation

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Imprint

1. Existing studies indicate that the impact of floating photovoltaics on the fish population in large water bodies is insignificant.

2. Floating photovoltaic systems can be a solution for a sustainable food-energy-water nexus.

3. Enormous potential of floating photovoltaics worldwide, including India.

4. Advantages of floating photovoltaics include an increased power conversion efficiency and significantly reduced evaporation of water bodies.

5. Worldwide lack of long-term environmental impacts assessments for floating photovoltaics, especially of shading effects, mainly due to youth of this technology.

Keywords: photovoltaics, floating photovoltaics, floatovoltaics, aquaculture, aquavoltaics, renewable energy, fish farming, food-energy-water nexus web, power production, sustainable development, food production

Key Findings

With decreasing land availability for new solar projects, water bodies have become an interesting alternative to ground-mounted systems. Considering freshwater man-made reservoirs, the World Bank estimates a potential of 400 Gigawatts (GW) for FPV globally (World Bank, p. 9). FPV systems are built out of same photovoltaic (PV) panels like land-based PV systems, but the modules are floating in the water, mainly suspended on floats and tethered to the land. Possible FPV installations include water bodies such as oceans, lakes, lagoons, reservoirs, irrigation ponds, wastewater treatment plants, wineries, fish farms, dams and canals (Abid, p. 2). This indicates even higher potentials compared to values from World Bank. In mid-2018, the cumulative installed capacity of FPV was 1,100 Megawatts (MW), whereas China is predominantly leading the global market in terms of installed capacities, followed by Japan and South Korea (Bridge to India, p.4). In India, FPV installations with total 2.72 MW have been commissioned until year 2019, at the same time additional 367 MW are under development (Bridge of India, p. 6; TERI, p. 10). According to a recent study of the energy and environment think tank TERI, India has suitable water surface areas of 18,000 sq km, holding a potential of 280 GW installed capacity in terms of FPV (TERI, p. 10).

Figure 1 (left): Floating PV power plant on water reservoir, Agongdian river, Taiwan Source: https://www.flickr.com/photos/shengdianye/44268494250/

Figure 2 (right): Floating PV power plant on lake in Walden, Colorado Source: https://www.flickr.com/photos/nrel/44606878545/in/photostream/

FPV gets into focus as these systems provide several advantages compared to conventional ground-based PV installations. PV arrays on water bodies provide a solution for land scarcity, avoiding potential future disputes in land use. PV modules in FPV arrays show an increased power conversion efficiency, due to the cooling effect of water evaporation and less dust on to accumulate on modules (Pringle, p. 6; Sahu, p. 819). According to different studies, the efficiency of PV modules on water bodies is 5 – 22 % higher compared to ordinary ground-mounted PV modules (Pringles, p. 20) with an average of 11 % higher efficiency due to a review study (Abid, p. 2). The physical shading effect of FPV plants leads to a decreased overall evaporation rate of water bodies, which is beneficial for reservoirs or hydroelectric dams. Results of scientific studies show that evaporation of open water bodies can be prevented by 33 to 50 % (Abid, p.5), leading to a more efficient water supply and more electricity from hydropower plants. Preventing water bodies to reach critical low water levels or even to dry up, the effect of evaporation reduction has a very positive effect on the survival of living organisms in water bodies (Abid, p.

Scientific Evaluation

6). This positive effect is considerable for many Indian regions where the level of evaporation is larger than the level of precipitation. As result, FPV systems can become part of sustainable food-energy-water nexus webs providing a solution for arid climate zones with water scarcity or droughts.

Figure 3: Example layout of a floating PV power plant. From Sahu et al. (2016), p. 818. Installed on reservoirs, close distances between FPV plants and energy demanding centres like cities can be assumed, which enables local power production and consumption, hence increasing added value within these communities (World Bank, p. 1). At hydropower sites a possible utilization of existing grid infrastructure might lead to lower investment costs (Pringle, p. 6,20; Château, p. 655).

Water bodies provide habitats to a diverse number of aquatic plants and domesticated animals, building together complex and sensitive ecosystems. Biodiversity can be affected easily and through numerous factors, including FPV. Minor impacts might be borne out of underwater electric cables or other FPV objects and materials in the water (Sahu, p 824). The main concern is seen in less sunlight being absorbed by the water body. On the one hand, this is considered to improve water quality for water bodies with persistent high algae production as the covering of water surface induces decrease of algal growth (Château, p. 655). Besides reduction of algae blooms, general plant life and density of photosynthetic microorganisms are being decreased through FPV installations, which might impact aquatic ecosystems negatively as oxygen levels drop (Pringle, p. 5, Château, p. 655). How much area of a water body could be easily covered without negative effect on oxygen levels is yet to be assessed (Sharma et al. 2015). However, experiences from existing MW scale plants do not show that aquatic life present in respective water bodies is decreasing (Sahu, p. 820, Gamarra, p. 32 – 45).

Figure 4: Development of fish population in relation to the installed capacity of floating-PV modules. From Chateau et al. (2019), p. 654.

Two major concerns regarding fishing and FPV have been identified through worldwide literature review. One is in terms of the development of fish population itself. Scientific studies indicate that FPV either increase or only slightly decrease fish production with high levels of modules covering more than 30% of the water body with solar. The results of a study with milkfish show estimated reduction in fish production between 5 and 10 %, under a high 60 % cover rate of FPV, see figure 3 (Château, p. 660). However, losses in fish production are overcompensated by gains in terms of energy (capacity of around 1.13 MW/ha), leading to an overall economic benefit (Château, p. 654). Other studies argue that fish population will increase because FPV arrays provide shelter for fish from hunting birds and to hide from fishermen. Besides, floats can act as artificial reefs and/or fish aggregation devices, able to restore damaged ecosystems and hence increasing overall amounts of aquatic life (Pringle, p. 15). In this context, Swimsol, a company which provides FPV offshore ocean systems to luxury resorts on Maldives conducted a detailed environmental study. Results show significant positive effects of these near-shore FPV systems, such as new coral growth, whereby the platforms have become a habitat for fish and crustaceans (World Bank, p. 65, p. 121 - 122). It is important to note, that each water body is different, and that man-made reservoirs and natural water bodies need different considerations, particularly in terms of environmental impact. In general, it is crucial to stay clear from the so-called ”littoral zone”, i.e. the area between the shore side and the point of depth where the sunlight still reaches the bottom of the reservoir. There, the highest degree of biodiversity occurs. Especially because so far the largest FPV systems are installed on man-made reservoirs without intensive bio life there is limited research done on the issue. For instance, the largest system worldwide (70 MW) in China, Anhui Province, is located on flooded former coal mines (Reindl, 2020, Webinar International Solar Energy Society). Therefore, there is general need for more research on different water body ecosystems in order to identify relevant effects of FPV systems.

Another concern related to FPV are potential economic losses due to limited access of fishermen and women to fishing grounds which are covered by FPV arrays. Restriction of access to the fishing area may occur also during installation phase, as construction material might block roads to access the water body. As actual concerns regarding fishing refer rather to the structure on the water body than its impact on the fish population, it is

perceived as important to involve local communities in the planning of FPV plants, especially if they are depending on the water reservoir for fishing (World Bank, p. 105, ERM Vietnam, p. 62 - 64). To avoid interference with commercial and sport fishing it is recommended to position floats not too close to the waterfront separating the larger installations in islands with possibility to give special permissions to fisherman to navigate in between floats, allowing them to finally catch even more fish (ERM Vietnam, p. 64).

To address existing concerns about FPV technology, experts from World Bank agree that there may be a need for enhanced monitoring for first floating solar projects to gather evidence of the environmental impacts of FPV projects on fish and other aquatic life. Concessional or grant financing of development banks shall be made available for the same (World Bank, p. 12).

The importance of FPV is predicted to further rise with potential offshore ocean applications not only limited to fish farming but also including water desalination, shipping, data centre cooling and even hydrogen production (World Bank, p. 20). With large water bodies in eastern, southern and south-eastern parts of the country in states such as West Bengal, Assam, Orissa, Andhra Pradesh, Tamil Nadu and Kerala, FPV is a promising technology for India to reach its future renewable energy targets.

Abid, M.; Abid, Z.; Sagin, J.; Murtaza, R.; Sarbassov D.; Shabbir, M. Prospects of floating photovoltaic technology and its implementation in Central and South Asian Countries. International journal of Environmental Science and Technology 16(1), (2018), pp. 1-9. https://doi.org/10.1007/s13762-018-2080-5. Bridge to India: Singhal, Deepak; Suresh, Sangeetha; Arora, Shipra; Singhvi, Surbhi; Rustagi, Vinay. Floating solar – opportunities and way ahead. Bridge of India report, Gurgaon (2018), pp. 1 - 12. Bruns, Elke; Department Head, Kompetenzzentrum Naturschutz und Energiewende (KNE) gGmbH, Berlin. Email exchange with Mr. Tobias Winter (IGEF-SO), 29 August 2019. Château, Pierre-Alexandre; Wunderlich, Rainer F.; Wang, Teng-Wie; Lai, Hong-Thih; Chen, Che-Chun; Chang, Fi-John. Mathematical modeling suggests high potential for the deployment of floating photovoltaic on fish ponds. Science of the Total Environment 687, (2019), pp. 654 - 666. https://doi.org/10.1016/j.scitotenv.2019.05.420. Environmental Resources Management (ERM) Vietnam. Initial Environmental and Social Examination Report – IESE Da Mi Floating Solar Power Project. Ho Chi Minh City, (2018), pp. 1 - 93. International Solar Energy Society (ISES). ISES + GSC Webinar: Floating Solar Photovoltaics. 28.05.2020. https://www.ises.org/webinars/665 Gamarra, Carlos; Ronk, Jennifer J. Texas Water Journal, Volume 10, Number 1, (2019), pp. 32 – 45. ISSN 2160 - 5319. Pringle, Adam M.; Handler, R.M.; Pearce, J.M. Aquavoltaics: Synergies for dual use of water area for solar photovoltaic electricity generation and aquaculture. Renewable and Sustainable Energy Reviews 80, (2017), pp. 572 - 584. https://doi.org/10.1016/j.rser.2017.05.191. Sahu, Alok; Yadav, Neha; Sudhakarc, K. Floating photovoltaic power plant: A review. Renewable and Sustainable Energy Reviews, Volume 66 (2016), Pp. 815 - 824. https://doi.org/10.1016/j.rser.2016.08.051. Sharma, Paritosh; Muni, Bharat; Sen, Debojyoti. Desgin Parameters Of 10KW Floating Solar Power Plant. International Advanced Research Journal in Science, Engineering and Technology (IARJSET), Vol. 2, Special Issue 1, (2015), pp. 85 - 89. ISSN (Online) 2393-8021 / ISSN (Print) 2394-1588. The Energy and Resources Institute (TERI). Floating Solar Photovoltaic (FSPV): A Third Pillar to Solar PV Sector? New Delhi, (2019). The World Bank; ESMAP; SERIS. Where sun meets water: floating solar market report, executive summary. Washington (D.C.): World Bank, (2019).

References

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