The Fisheries Research Institute and the National Academy of Marine Research have collaborated to successfully cultivate macroalgae in Taiwan's offshore wind farms for the first time, thus, reversing the previous belief that macroalgae could not be cultivated in subtropical Taiwan due to the high summer water temperatures and nutrient-poor marine environments of the surrounding seas. This technology for establishing artificial marine surface algal farms can be further applied to the research of marine algal carbon sinks and shared areas of offshore wind farms with fisheries, which is a big step forward in the research and development of marine carbon sink technology under the Ministry of Agriculture's "Key Strategic Action Plan for Natural Carbon Sinks".
According to the Fisheries Research Institute, since 2019, it has made several attempts to build marine artificial algae farms at Taiwan's first offshore wind farm - Ocean Wind Power (Formosa 1), located off Miaoli; however, all such efforts have ended in failure. The reasons for the failure include the difficulty of obtaining large quantities of algae from the wild, the unfavorable conditions for algae growth caused by the high turbidity of the sea water due to the sandy and muddy bottom in the western part of the sea, and the damage to the aquaculture facilities caused by the large waves of typhoons and monsoons. In order to break through the existing situation, in 2023, the Institute cooperated with the National Academy of Marine Research to build a land-based algal mass production facility at the Mariculture Research Center of the Fisheries Research Institute in Cigu District, Tainan to produce sufficient and stable sources of domesticated algae. On July 12, 50 samples of Caulerpa lentillifera (common name: sea grapes), each containing 100 g of algae at the high unit price of NTD 2,000 to NTD 2,500 per kilogram, were deployed for a trial at an improved artificial marine surface algal farm facility in the vicinity of the Marine Wind Power Sea Weather Observation Tower. A further visit to the marine algal facility on August 27 was arranged to check the released Caulerpa lentillifera samples, which revealed that half of the samples survived. The average weight gain of the surviving samples during the 46-day period was 3.69 times the original weight, with the heaviest sample reaching 9.5 times. This trial was initially assessed to have high carbon sink and economic potential.
The Fisheries Research Institute stated that after the successful cultivation of Caulerpa lentillifera in July, Gracilaria firma, Gracilaria edulis, Acanthophora spicifera, and Chaetomorpha crassa, which are common and economically valuable macroalgae in the local area, were deployed in August, and the institute continued to observe the adaptive survival of each type of algae. After the passage of Typhoon Saola and Typhoon Haikui through the Taiwan Strait in August and September, the facilities remained intact, and the cultured Caulerpa lentillifera and Gracilaria firma continued to grow and gain weight. Among them, 28 samples of Gracilaria firma survived, and their maximum growth rate reached 6.5cm in one month. This is the first time that the Institute has successfully cultured macroalgae in Taiwan's offshore wind farms, which has overturned the previous belief that macroalgae cannot be cultured in the surrounding seas of subtropical Taiwan due to the high summer water temperature and nutrient-poor marine environment.
The Fisheries Research Institute pointed out that the ocean is currently a key issue for global carbon sinks, and has the potential to play an important role in the "carbon rights" and "carbon transaction market" issues of Taiwan's fisheries industry in the future. The overlap of the area planned for Taiwan's offshore wind farms and the traditional fishery operation area is crowding out each other's space utilization. If the vast area between the wind turbine foundation piles can be utilized as an offshore algae farm facility, and the fishermen are provided with the opportunity to switch to seaweed aquaculture, it will solve the problem of the shrinking operating area of the local fishermen and transform their fishery methods, and enable the harvested algae to be sold to food, cosmetic, pharmaceutical, and industrial industries, which will increase the autonomy of algae utilization in Taiwan and enhance the economic income of fishermen. In addition to the green energy generated by wind turbines, offshore wind farms also have the function of creating carbon sinks for seaweeds and the conservation of fishery resources, which helps to establish the triple benefits of green energy, carbon sinks, and conservation of fishery resources. If 5% of the total area of about 3,084.5 square kilometers of the potential site of the offshore wind farms is provided as a marine algae farm facility, it is expected to increase carbon sinks by 17,000 to 26,000 tons per year. If a further 1% of Taiwan's 65,000 square kilometers of territorial waters are used for algae farms, it is expected that carbon sinks would increase by 6.5 to 9.75 million tons per year.
According to the Fisheries Research Institute, this technology for establishing artificial marine surface algal farms can be widely applied to the study of carbon sinks in marine algal farms and the shared waters of offshore wind farms and fisheries, which is a big step forward for the research and development of marine carbon sink technology under the "Key Strategic Action Plan for Natural Carbon Sinks" of the Ministry of Agriculture.
Figure 1. Improved marine artificial surface algae farm facility of the Fisheries Research Institute near Marine Wind Power Sea Weather Observation Tower off Miaoli.
Figure 2. Successful aquaculture of Caulerpa lentillifera (common name: sea grapes) in marine artificial surface algal farm facilities