Session: 09-03-01 Wind Energy: Installation

Submission Number: 155231

Reduction of Total Installation Time for Floating Offshore Wind Farms by Improving Actual Unit-Installation Time and Optimizing Operation Windows 

Recently, to pursuit of carbon neutrality, offshore wind energy installations have been expanding in regions such as Europe, China, and Japan.  Offshore floating wind technology, including the optimization of floater and mooring system, as well as advancements in installation methodologies, have been developed to reduce the Levelized Cost of Electricity (LCOE) for commercialization. A key factor in this effort is the reduction of offshore installation costs. The installation cost can be estimated by multiplying the daily rates of the installation vessels and the number of days required for installation. Previously, an installation time estimation model of Floating Offshore Wind Farm (FOWF) was proposed based on a cost breakdown structure, and unit-installation time was estimated using data from the FOWF demonstration project. However, since this unit-installation time includes weather downtime, it is challenging to apply it to other areas with different met-ocean conditions. Therefore, it is necessary to introduce actual unit-installation time excluding weather downtime, and to consider operational windows that reflect local met-ocean characteristics. Recently, the actual unit-installation time was estimated for Hywind Scotland. To the best of our knowledge, no studies have focused on the comparing actual unit-installation time for other FOWT, or operational windows for different sites around Japan.

The objective of this paper is to propose an installation time estimation model for FOWF that incorporates metocean characteristics specific to the project site, expanding upon our previous model. Using installation data from the Fukushima floating offshore wind farm demonstration project in Japan, actual unit-installation time is estimated and compared with data from Hywind Scotland. It was found that the total time for pre-installation per mooring line and holding time per anchors in Japan is 4.3 times longer than in Europe. For submarine cables, time required to connect one side of the riser cable to the floater, as well as the time for trenching cables, are 4.0 and 7.5 times longer, respectively, compared to the corresponding times in Europe. In contrast, the time required for connecting mooring lines to the floater remains at a similar level. Additionally, total installation time was estimated for five project sites: Aichi, Akita, and Nagasaki in Japan, Ulsan in Korea and Hsinchu in Taiwan, assuming a FOWF model. The total installation time is estimated to be reduced by approximately 50% by adjusting actual unit-installation time and weather restrictions from the current conditions in Japan to those of Europe.

The model offers a more generalized framework for estimating installation time of FOWF compared to previous methods. It can qualitatively assess the impact of new technologies and contribute to the formulation of technology development policies for FOWF installations, such as setting a specific target for technology advancement.

Presenting Author: Tomohiro Hasumi National Maritime Research Institute

Presenting Author Biography: Graduated from department of applied physics, Waseda University on 2009.3
Worked at Mizuho Information and Research Institute, Inc, until 2022.3
Worked as a senior researcher at National Maritime Research Institute Japan from 2022.4
Worked as a principal researcher at National Maritime Research Institute Japan from 2024.4