Bigger turbines and rougher seas. Today’s offshore wind installations require a more robust jack-up vessel.

With more powerful turbines and in rougher locations, projections suggest offshore wind capacity could reach 500 gigawatts by 2035. But this raises a practical question: How to transport and lift bigger components in choppy seas? Wind farm contractor Cadeler has found an answer to heavier lifting with a new wind turbine installation vessel (WTIV) that uses a unique customized-engine configuration – and they’re saving emissions while they are at it.

By Justus Krüger

In partnership with MAN Energy Solutions and COSCO Shipyard in China, Cadeler is constructing five state-of-the-art WTIVs. The first vessel, Wind Peak, was delivered in August 2024. The second, Wind Pace, was set for Q1 2025. Both P-class vessels are designed to operate in some of the most difficult sites around the world, with a unique hybrid-engine and electrical energy storage concept and the most advanced equipment in the industry. 

Lowering ship weight and increasing engine efficiency

What sets the P-class vessels apart is their innovative engine configuration, provided by MAN Energy Solutions. Instead of relying solely on medium-speed engines, as most WTIVs do, these vessels also include lighter, high-speed engines. Each vessel will have an engine configuration based on a mixed MAN medium- and high-speed engine concept with two 9L32/44CR, two 6L32/44CR and two 12V175D engines. As a result, P-class vessels will have higher lifting and transport capacity compared to a traditional engine set up.

A single medium-speed engine can weigh around 54 tons, while a high-speed engine comes in around 9 tons. Replacing a set of medium-speed engines for high-speed ones saves considerable weight. “This is significant,” says Henning Bullwinkel, Global Manager Wind Offshore at MAN Energy Solutions. “The less weight the WTIV itself has, the more wind farm components it can transport in a single trip.”

For the P-class, the weight savings allow it to transport up to six sets of 15 megawatt turbines or five 20+ megawatt turbines in a single trip. That’s a big leap forward in efficiency, considering the size and weight of modern turbines that will have taller hub heights and larger rotator diameters. Newer nacelles alone, which house the generating components of wind turbines, can weigh up more than 700 tons.

With increased transit capacity, the new Wind Peak lowers the energy demand for transporting and installing turbines, reducing costs, installation time, fuel consumption and emissions. “MAN Energy Solutions is the only provider of this unique mixed engine-configuration,” says Elvis Ettenhofer, Head of New Marine Solutions at MAN Energy Solutions, ”with the highest efficiency, lowest weight and the greatest payload – we believe this will provide value to Cadeler.”

WTIV peak power loads: lifting and positioning

The dual-engine setup also helps the P-class handle the fluctuating power demands of wind turbine installation. For example, an unusual feature of WTIVs is their ability to lift themselves entirely out of the water using extendable jack-up legs. This stabilizes the ship during installation, shielding it from waves and currents. Lifting a ship out of the water and onto its legs produces one of the peaks in energy demand.

This is where the high-speed engines come in. These engines are ideal for tasks that require a temporary energy supply, such as lifting or positioning. Meanwhile, the medium-speed engines, robust and built for steady, long-term operations, are well-suited for handling base energy loads, making the engine setup particularly effective in this context.

Dynamic positioning (DP) is another peak energy challenge these vessels must tackle. This technology keeps the ships steady without anchoring by using thrusters and sensors to counteract currents, wind, and waves. 

In a crowded wind farm, drifting could cause a collision with a turbine. DP systems constantly monitor the ship’s position and activate the thrusters to maintain precision. “Dynamic positioning ensures that the ship does not drift even by a few meters, but stays completely stable in one spot,” says Henning Bullwinkel. 

During transit to the wind farm the medium-speed engines provide fuel-efficient, steady power. This flexibility afforded by utilizing both medium- and high-speed engines means the ship can handle a wide range of power needs with improved energy efficiency.

A strategic partner in offshore wind projects

“We are a big part of our clients’ business case,” says Jacobsen. “You can be assured that this is a highly optimized asset designed to support them in the best way. We match the engine configuration to the operational profile so that we always have the capability of running the engines efficiently in any mode, which is why we have three different sizes of engines, so in any operational mode − whether we’re jacking up the ship, in transit or in port − we can match the expectations of having the vessels operating more energy-efficiently.”

Jacobsen emphasizes that the vessels are carefully designed around client requirements to ensure that operational priorities are directly addressed. “We analyze what the actual needs are, and then we design everything in the vessel to support these needs. Every detail in the vessel has been scrutinized and evaluated on how it safely and most environmentally supports the mission of the client.”

From deck layouts to workflows, each choice is made to ensure that vessels integrate seamlessly into the logistical demands of offshore wind projects. “The vessels are not supposed to do anything other than making sure that our clients get the best service and their operations are optimized as much as possible,” adds Jacobsen.

Methanol-ready for the future

Another forward-thinking feature of the P-class vessels is their methanol-ready engines and tanks. Methanol is an increasingly plausible alternative to traditional marine fuels. It produces significantly lower emissions and is currently on the way of becoming a major fuel alternative in shipping, with some of the world's largest shipping firms in the process of switching to greener fuels such as climate-neutrally produced methanol. Having its ships methanol-ready and able to operate on various biofuels ensures that Cadeler is well-positioned to adapt to future fuel transitions and play an active role in the shipping industry’s shift toward climate-neutral alternatives.

As offshore wind capacity continues to expand the infrastructure supporting it must evolve to meet complex demands. The P-class vessels are a reflection of this shift, designed to tackle fluctuating power needs and the logistical challenges of transporting and installing massive turbine components.

“Offshore wind plays a big role in reducing emissions and producing green electricity at low costs. Equally important it helps to reduce dependencies from energy imports” says Henning Bullwinkel, “Besides the described WTIV, Offshore wind is creating a demand for vessels of all kinds active in this area. We have the right technology to answer all requests arising from this market, and we’re proud of our contribution to a carbon-neutral future.”

About the author

Justus Krüger is a freelance journalist based in Hong Kong. He has written for the Financial Times Deutschland, GEO, the South China Morning Post, the Berliner Zeitung, and McK Wissen.