Some wind installation vessel owners are looking to the offshore oil and gas industry to meet the fast-growing demands of offshore wind, writes Esgian’s Hieronymus Bassoe
The offshore wind industry has experienced significant growth in the past couple of years due to the energy transition picking up pace and the subsequent heavy investment in alternative energies. As turbine sizes and project numbers grow, demand for specialised wind installation vessels (WIVs) is set to reach new highs and with the current limited capacity, it is expected there will soon be an undersupply of vessels.
Today there are 10 WIVs under construction. There are a few more purpose-built units planned, but construction on the majority of these has not yet begun and they have therefore been excluded from the accompanying table. More units will be needed to help install the growing backlog of ordered turbines, especially vessels big enough to accommodate the increasing size of these assets too.
However, ordering a newbuild vessel is not the only option. There have been various instances of companies converting offshore drilling rigs for wind installation work.
Drilling rigs converted for offshore wind
In 2017, Boskalis purchased Transocean’s idle 2000-built ultra-deepwater drill ship GSF Jack Ryan for a reported US$8M with the sole purpose of converting it for offshore wind installation. The drill ship, now renamed Bokalift 2, is currently at Drydocks World in Dubai. The vessel is due to be finished in early 2022 and it will be put to work at the Changfang and Xidao projects in Taiwan. Copenhagen Infrastructure Partners awarded Boskalis a deal valued at €150-300M (US$176M-US$353M) for the two projects, covering the installation of 62 jack-up foundations and 186 pin piles.
Meanwhile, earlier this year, SinoOcean entered into an agreement with a local Chinese company to convert and bareboat charter two idle jack-ups for work at offshore windfarm installations in Chinese waters. In addition, SinoOcean also reportedly plans to convert an offshore tender rig for the same purpose.
Similarly, CIMC Raffles recently completed the conversion of a stranded jack-up to work locally in China.
How does a drilling rig become an offshore wind vessel?
Vessel requirements for offshore wind installation and offshore drilling are substantially different and most operations demand different assets. Offshore wind installation vessels need heavy lifting and deck space capabilities and a hull designed to accommodate a good speed.
To prepare rigs for their move into renewables, the hull can be enforced, the deck space increased, and heavy lifting capabilities installed. For example, on Bokalift 2, the former drillship will have 9,000 tonnes of steel blocks installed on both sides to increase its stability and have a new work deck put in place. The drill ship will also have a new 4,000-tonne Huisman crane installed, capable of lifting structures 100 m above the deck.
The stranded Chinese jack-ups appear to need less upgrading for their transition into the wind market. It is understood the two units have had their rig towers and beam cantilevers removed, while the deck has been modified and a crane with heavy-lifting capabilities is now installed.
The SinoOcean tender rig is to be stripped of its drilling equipment and replaced with a 400-tonne crane. The vessel is suited for shallow water operations, making it ideal for offshore wind operations.
Conversion versus construction: the pros and cons
Although converted drilling rigs might not be as efficient as a special purpose-built WIV, they do have their benefits. Converting rigs is potentially less costly than ordering a newbuild. Also, while the construction of a brand new WIV could take up to three years to complete, a conversion (particularly in the case of jack-ups) takes less time.
Based on data from Boskalis’ financial reporting, we estimate the Bokalift 2 conversion costs will be in the €100-200M (US$118M-$236M) range, or less than half the cost of a specialised newbuild.
Installation jobs undertaken by ex-rigs may be simpler than those done by purpose-built units due to their lack of mobility and deck space capacity. Even so, converted rigs will serve other important roles needed in the offshore wind segment. The market seems to have focused on vessels capable of installing turbines rather than foundation installation. These converted rigs can help fill the supply void until the industry builds more specialised foundation vessels, such as Alfa Lift, Les Alizes, and Green Jade.
Owner | Vessel name | Design | Work type | Delivery | Cost |
Jan De Nul | Voltaire | Knud E Hansen | Turbine | 2022 | not available |
Jan De Nul | Les Alizes | Foundation | 2022 | not available | |
Eneti | not available | NG16000X | Turbine | 2024 | US$330M |
OHT | Alfa Lift | Ulstein Design | Foundation | 2021 | US$300M |
OHT | Vind 1 | NG14000XL-G | Turbine | 2023 | US$255M |
Shimizu | not available | SC14000XL | Turbine | 2022 | US$462M |
Cadeler | not available (X-Class) | NG20000X-G | Turbine | 2024 | US$325.5M |
Cadeler | not available (X-Class) | NG20000X-G | Turbine | 2025 | US$325.5M |
Dominion | Charybdis | NG16000X-SJ | Turbine | 2023 | US$500M |
CDWE | Green Jade | Foundation | 2022 | not available |
Specialised wind installation vessels under construction; source: Esgian Wind Analytics and Riviera Maritime Media reports
A growing trend?
As aforementioned, the majority of rig to WIV conversions have happened in China, for the benefit of Chinese projects, as companies scramble to secure any vessel capable of working in offshore wind before government subsidies end in November this year.
Outside of China, the market undoubtedly feels the pressure of a lack of WIV availability, yet these other areas have time to spare for more specialised newbuild vessels to enter the market. These converted rigs so far remain limited in numbers and are unlikely to be part of the long-term solution as the offshore wind vessel sector will remain a highly specialised market, requiring purpose-built units.
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