The Firefly Floating Offshore Wind Project is planned to be developed offshore Ulsan, South Korea. (Credit: Equinor ASA)
Illustration of a Wind Semi being towed for the development of the Firefly offshore wind farm. (Credit: Equinor ASA)
Illustration of the Equinor Floating Offshore Wind Power Complex, Firefly project. (Credit: Equinor ASA)

The Firefly (Bandibuli) Floating Offshore Wind Power Project is being planned to be developed 70km off the Ulsan coast in South Korea with an investment of several billion dollars.

The project, which will have a capacity of around 800MW, will be developed by Equinor South Korea.

In 2019, Equinor signed a memorandum of understanding (MoU) with Ulsan City for the development of the wind power project. A year later, LiDAR 1 and LiDAR 2 were installed to procure wind data.

In December 2021, Equinor commenced surveys to collect data for the Environmental Impact Assessment (EIA). The surveys were conducted over a 12-months period. The Ministry of Trade, Industry, and Energy in South Korea granted permission for the project in the same month.

The EIA Scoping Report was published in 2022.

Construction works for the project are expected to start in 2025, with operations planned to begin from 2027.

Firefly Floating Wind Project Location

The Firefly Floating Offshore Wind Power Project will be located within the public waters of Exclusive Economic Zone (EEZ) in South Korea. The site is around 60-70km from the east coast of Ulsan Port.

The project will include two 75km2 areas across a 154km2 site.

Firefly Floating Offshore Wind Power Project Details

Equinor plans to use a low draft semi-submersible concept – the Wind Semi, for its floating wind projects in Korea. The decision was taken after assessing supply chain, demand and climate conditions near the coastline.

According to the EIA Scoping Report in 2022, Firefly floating wind farm is expected to include 54 wind turbines of 15MW capacity each. This will provide the project with a total capacity of 810MW.

With a hub height of 156m, the wind turbines will have a rotor diameter of 236m.

Although Spar Buoy type and Tension Leg Platform type were considered, the project selected Semi-Sub floating type concept for the wind farm.

The Semi-Sub type was selected after assessing water depth, shipping, installation, and maintenance operations, as well as due to the availability of multiple Korean shipbuilding companies with experience in manufacturing the type of foundation.

The mooring line for the project will be appropriate for Semi-sub floating, and general catenary will be selected. After an oceanographic survey, the mooring system to secure catenary will be decided.

Each turbine will be connected to a network of underwater cables and then to the floating or fixed type offshore substation. At the substation, the voltage will be increased from 66kV to 230kV for transmission to the onshore substation.

The 70km long unwater export cable will make a landing at Southern Ulsan at the on-land substation location. After landfall, the three-phase cable will be separated into single-phase cable and then connected to the substation.

An on-land 5.5km transmission line of 345kV will connect on land landing point to the Korea Electric Power Corporation (KEPCO) substation in Ulju-gun, Ulsan, from where the electricity will be fed into the grid.

Contractors Involved

Equinor Korea entered into vendor agreements with professional services firm RPS and Sekwang Engineering for Environmental and Social Impant Assessment (ESIA) and Environmental Impact Assessment (EIA) for the offshore wind project.

In April 2022, Equinor South Korea awarded a Front-End Engineering and Design (FEED) contract for the Firefly project to French engineering and technology company Technip Energies.

The scope of FEED work will include engineering of the floating wind turbine substructures of the project. The substructure design will include Technip Energies’ in-house floater technology INO15, a three column semi-submersible floater suitable for large series fabrication in large series.

Denmark-based COWI was selected to serve as the ‘owner’s engineer’ for the wind farm project. Under the contract, COWI employees will be added to Equinor’s project development team. The contract will cover independent services, reviews, and engineering services besides project management and technical services.

Equinor awarded South Korean marine surveying company GeoView the contract for subsea geophysical surveying and mapping for the project. GeoView No 1, a marine survey vessel of GeoView, will be used for the survey.