Floating Solar Energy

What are FPVs

Floating photovoltaic (FPV) systems are comprised of arrays of photovoltaic modules similar to classic solar farms; however, rather than mounted on the ground these arrays are attached to individual floats comprised of high-density polyethylene (HDPE) or fiber-reinforced plastic which often maintain their position with the assistance of proper moorage and anchorage. Mooring is essential in maintaining FPV module positioning and resisting wind, waves, etc. The two primary moorage methods, traditional and elastic differ in that elastic systems both reduce force impact and require less material and lines to create. Moorage lines are connected to anchors that are weighed down by concrete to minimize wind impact and maintain positioning. Anchorage systems can also vary depending on the water depth and positioning and can vary from bottom to bank anchoring. FPV systems themselves come in several designs as well.

These systems can be utilized in freshwater environments such as lakes or reservoirs as well as in oceans and lagoons. To reap the benefits of FPV systems large energy infrastructure must be created such as long transmission cable systems; however, oceanic FPV systems may be able to use similar existing infrastructure utilized by off shore wind farms. These farms often utilize thick and long transmission cables buried under the sea bed and connect to the wind turbines at the bottom of the ocean.

Creating connections to the grid for large freshwater FPV systems are much less costly as they are significantly closer to the shore and require shorter cables. With consistent development of offshore energy infrastructure, widespread creations of FPV farms will become even more widely used and tap into to potential 400 GW of floating solar capacity in all man-made water bodies around the world, not including oceans and lakes.

Two major dark sides of solar power are the poor energy conversion efficiency and major land usage. FPVs can help address both issues. In addition to their bifacial properties, that may increase power production by 10-20% compared to single-sided FPVs, FPVs greatly benefit from the natural cooling system provided by the water of which the system rests on.

In oceans, FPVs are cooled by the water while the ocean is cooled as well; since the irradiance is reduced by 73% when FPVs are placed on lakes, similar impacts could occur in the ocean and contribute to slowly reversing the immense damage our aquatic ecosystems have faced due to global warming.

220,000 TWh of potential generation- enough energy to power a global population of 11 billion human beings.

- Australian National University-

Current Utilization

Global governments and institutions are leading the way across the world in utilizing FPVs, truly displaying their immense potential worldwide. China has worked with Ocean Sun -a Norwegian company working to revolutionize FPVs- in making enormous FPV farm experiments off the coast of Haiyang, a coastal city in Southeastern China, containing 770 solar panels. The project showed immense potential and despite possible environmental issues with waves reaching heights of ten meters, Ocean Sun founder, Bjørneklett, acknowledges China as an immense land of opportunity due to the current advancement of FPV technology as well as a very complete industry chain. As China is the largest energy consuming countries at approximately 159.39 billion kWh, supplementing this demand with FPV energy will have colossal benefits in our global effort towards sustainability.

Energy companies in other nations have implemented FPV systems and also foresee major promise. The company from Norway that worked in Haiyang, Ocean Sun, has utilized FPVs that could withstand up to 171mph in wind gusts. Solar2wave of Indonesia has found that their FPV systems can tolerate waves as tall as 5 meters and French company HelioRec could face both 62mph winds and 7 meter high waves. As the Australian National University believes that within regions that experience waves less than 4 meters tall and winds as fast as 33.5 mph, there is

220,000 Twh of potential generation- enough energy to power a global population of 11 billion human beings. Man-made freshwater bodies also provide 400GW of energy potential.

Duke University has led the charge in the United States in hoping to tap into the potential the FPV market contains. In a 1,200 acre pond at the Hines Energy Complex in Bartow, Fl 1872 solar panels have been utilized in an extremely effective case study experiment analyzing the potential of FPV systems as a part of Duke Energy's Vision Florida Program. The study found that the FPV farms durable enough to resist environmental forces and maintain stable position. The system was also easily maintained with the addition of floating walkways for inspection and did not damage the local ecosystem. As Duke built the system while thinking of both humans and animals, alligators, fish, and birds were practically unbothered by the FPV additions. The usage of thoughtfully designed FPV systems has contributed to the 7,500 MW of clean solar energy Duke has connected to the grid, sufficient in powering approximately 750,000 houses. Although solar energy is rising in usage in the United States, it is insufficient and only 2% of solar farms are floating. Currently, FPV farms are being increasingly utilized globally, but must gain more traction in nations with major energy demand such as the United States to reap the true benefits of floating photovoltaic energy.

Concerns

Despite the undeniable positive benefit of FPV systems, economic and environmental concerns are prevalent and should be weighed into consideration. Current investment costs for FPV farms are greater compared to their on-land counterparts due to the larger infrastructure required to connect them to the grid. As America does not have a vast off-shore wind farm industry, off-shore FPV systems are more costly due to being forced to create entirely new infrastructure. Comparatively, other nations around the globe have invested greatly in off-shore wind, allowing for off-shore solar farms to utilize existing infrastructure rather than being forced to construct entirely new systems. However, with the increased efficiency of FPV systems, the long-term cost is only slightly higher and practically offsets the initial investment. Additionally, off-shore FPV farms may in fact be more cost effective than conventional PV farms as the infrastructure and land space required to supply energy to such a large nation is extremely costly. Ocean-based FPVs surrounding China's coast will reduce the distance electricity has to travel, reducing infrastructure costs, and also allows for land to be repurposed for agriculture and urban development. Although the costs of the floaters, mooring, and anchors will additionally increase costs, the benefit of minimal land usage will outweigh those costs enormously.

Besides these possible economic challenges, environmental roadblocks may serve as much larger obstacles. The FPV farms themselves alter local EMF, or electromagnetic fields, from their transmission cables which can cause major disruptions in local ecosystems. Benthic invertebrates, elasmobranchs, turtles, etc. could suffer from potential alterations in their navigation, possibly interfering in migratory patterns. FPV systems also provide shade, and in turn possible light deprivation in areas they cover. Such shade may be beneficial in freshwater environments in algae bloom prevention; however, reduced photosynthetic processes due to lack of sunlight reduce oxygen levels can reduce phytoplankton biomass which could have detrimental impacts in local ecosystems as phytoplankton are often producers: the foundational species of ecosystems. Zooplankton could adversely be impacted as well as lack of sunlight could change their natural vertical migration behavior. Examples of reduced biodiversity in shaded regions in the ocean are present under piers, suggesting that lack of sunlight could have real impact. However, major issues in biodiversity from FPV systems are unlikely as sunlight within the gaps of the FPV systems are large and consistent enough to mitigate immense consequences.

The panels themselves however may act as a larger environmental threat. Dragonflies, mayflies, caddisflies, and other aquatic insects have been seen, in large amounts, depositing eggs onto photovoltaic panels, killing them from the excessive heat. Resting pinnipeds may also face burns from the high temperatures and additionally damage FPV panels due to the immense weight and stress the large animals would exert. To mitigate injury to both the animal and the system, fencing may be utilized to discourage interaction with the system as much as possible.

Photovoltaic waste is a cause for concern as well. Although we know how to recycle 85% of materials found within photovoltaics, they are often not discarded properly as they are difficult to separate into their respective materials. The United States Department of Energy Solar Energy Technologies Office is working to innovate photovoltaic panels so that they are easily dismantlable and have longer lifespans as well. If solar panels increase their lifespans by 2-3 years, 2-3 million metric tons of waste would be prevented by the year 2050.