Hydropower & other renewables |
Right: The Port of Tazacorte in Spain. 275kWp Ocean Sun pilot floater with visitors enjoying walking on the thin membrane
be spared resulting in little conflict in licensing
processes. Existing hydropower owners will often be able to experience simplified licence applications to the authorities since they use their own reservoir site and no new expansions of the grid are necessary. The floating solar plant can provide additional energy by ramping down the hydro output accordingly in daylight hours, thus saving water for the evening peak load. This is much cheaper than building new hydro plants.
A common myth is that the reservoir area will limit References
Bjørneklett, Offshore floating solar – a technical perspective, PV Tech Power Magazine, 16 (2018) 60
Kjelstad et al, Cooling of floating photovoltaics and the importance of water temperature, Solar Energy 218 (2021) 544–551
the size of PV plant, but this is never the case. In practice it is almost always the capacity of the existing hydro units, transformers and transmission line which determines the optimal size for combined operation. A suitable site near the transformer station with short cable connection is usually found and most of the reservoir is unaffected. The first Ocean Sun system was constructed on the west coast of Norway by reusing an old floatation collar from a fish farmer. The first time we tested it we could walk and even run effortlessly across the 1mm thin membrane at sea. This was a big experience, similar to walking on a waterbed. Initially, it was thought we might need skis to distribute our weight more evenly but it was soon discovered that operators could move freely on the huge circular “sundeck”. Now we can walk safely on the panels during inspection and cleaning operations without causing damage, and are at no risk of falling into the reservoir. The next system was a 100kWp micro grid
Below: Experimental sea trials with two Ocean Sun floaters in the Yellow Sea
installation for Leroy Seafood, powering an aquaculture feeding barge equipped with diesel generator and battery back-up. The system was tested for one year in the relatively exposed location, and survived storms and waves up to 3m. A larger 250kWp system was installed on the Magat hydro power dam in the Philippines in 2019. This was the first hydro hybrid and the system could be benchmarked towards an air-cooled rooftop PV installation nearby. At a latitude of about 16 degrees north this system outperforms regular air-cooled panels by ca 10% higher yield. This pilot now has four years of successful operation and has survived several tropical cyclone episodes. The owner SNAP plans to expand it and has already installed a 20MW battery for smoothing combined hydro-solar operations.
After a troublesome start during the pandemic, Ocean Sun opened the 2MWp demonstrator with Statkraft in 2022 at the Banja reservoir in Albania. The system consists of four rings, 0.5 MWp each. It was erected over several weeks on a beach and towed into position, and has operated continually for over a year. The latest pilot is a marine water test unit recently
launched close to the port of Tazacorte, La Palma in the Canary Islands. This is the result of an EU-financed project named BOOST, in collaboration with Plocan, ITC, Inosea and Fred Olsen Renewables. It is a near shore installation in the Atlantic Sea and is exposed to open sea towards the south. Ocean Sun has also collaborated with the State Power Investment Corp for hybridisation with offshore wind turbines in the Yellow Sea in Shandong Province, China. This experimental system was relatively quickly taken ashore for further modifications.
The future The future for floating solar looks promising and the
hybridisation with hydropower plants is probably where the first multi-megawatt projects will come. The Ocean Sun solution is particularly suited in the tropics, warm climates and in areas exposed to high wind and waves. The catenary style anchoring of the circular floaters is suitable for reservoirs experiencing water level fluctuation of over 10m. Several of the pilots have received site-specific certification from third party maritime certification organisations, a prerequisite for insurance and general bankability of larger installations.
Author information The Authors are Dr. Børge Bjørneklett and Dr. Brian Glover. Bjørneklett is the founder and CEO of Ocean Sun and has prior experience from the automotive, offshore oil and gas and the solar industries. In 2016 he founded Ocean Sun based on an invention for floating solar plants. Ocean Sun has 15 employees and is listed on the Oslo Exchange. Glover is a member of the Board of Ocean Sun and has more than 40 years’ experience in renewable energy project development, mainly hydropower. He is a hydrologist and civil engineer who has worked in over 40 countries worldwide on dams and hydropower projects of all sizes and types.
30 | January 2024 |
www.waterpowermagazine.com
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