This paper aims to identify the gaps on the path to achieving sustainable development of floating offshore wind in Japan. Japan has a strong desire for floating offshore wind development, motivated by energy security, climate change, and industry promotion. The key challenges are described with an emphasis on the unique environmental conditions of Japan, such as earthquakes and tropical cyclones. In addition, the absence of oil and gas development in Japan has led to social challenges, such as a lack of supply chain, infrastructure, and human resources in offshore wind. A review of state-of-the-art technologies is provided in each technology domain for four research domains: site selection and characterization, technology and engineering, project execution and operation, and industry and economic enabling. The gaps identified in the paper suggest the need for specific research topics, such as the assessment of unique environmental conditions; the design of robust and cost-effective structures considering fabrication, transportation, installation, and operation; and the creation of a data sharing strategy for efficient and rapid learning. In addition, many challenges show technology gaps across domains, indicating the need for interdisciplinary research collaboration and system integration of complex systems with digital engineering approaches. Finally, the need for the development of an industry roadmap to address these challenges is discussed.

This paper aims to identify the technology gaps on the path to achieve sustainable development of floating offshore wind in Japan. Japan has a strong desire for floating offshore wind development motivated by energy security, climate change, and industry promotion. The key challenges are described with an emphasis on the unique environmental conditions of Japan, such as earthquakes and tropical cyclones. In addition, the absence of oil & gas development in Japan has led to social challenges such as a lack of supply chain, infrastructure, and human resources in offshore wind. A review of state-of-the-art technologies is provided in each technology domain for four research domains: site selection, design & operation, industry development, and contribution to national energy policy "S + 3E" or "Safety + Energy security + Economic efficiency + Environmental sustainability". The gaps identified in the paper suggest the need for specific research topics such as the assessment of unique environmental conditions, the design of robust and cost-effective structures considering fabrication, transportation, installation, and operation, and the data sharing strategy for efficient and rapid learning. In addition, many challenges show technology gaps across domains, indicating the need for interdisciplinary research collaboration and system integration of complex systems with digital engineering approaches. Finally, the need for the development of an industry roadmap is discussed.