As turbines get larger and offshore windfarms get more remote, the crane industry is lifting its game with more powerful, innovative equipment
As offshore wind turbines become taller and more powerful in the quest for cleaner energy, the crane industry is literally rising to the occasion, with giant and innovative heavy-lift technology that would have been considered impossible until recently.
“Compared with even five years ago, today’s cranes are off the scale,” Huisman manager newbuild sales Charlotte Roodenburg, told delegates at Riviera Maritime Media’s Taking the strain: cranes and lifting equipment for offshore vessels webinar in mid-September.
“These days the cranes are going for over 3,000 metric tonnes (mt). The overturning moment is 160,000 or 260,000 and booms are being asked for 175 m. This is a difference of only five years. We are almost doubling the capacity and booms are increasing by approximately 50%,” she said, summing up the pressure on the industry.
According to polls taken during the webinar, participants think the sky is the limit. Asked what the future capacity of 3D-compensated cranes would be, no less than 60% predicted it would be above 50 tonnes.
On top of a runaway increase in size, the industry is being stretched to the limit in other areas. Ms Roodenburg cited shorter timeframes in construction, tighter budgets in a low-margin electricity market, more remote and complex locations, and tougher contractual requirements.
“Once the vessel gets big, everything gets expensive”
All of these bring challenges in safety. “This means we have to go for a higher redundancy. We are being asked for hands-off operations, of course, and we need to have adequate emergency procedures in case something goes wrong,” she said.
In short, this highly specialised industry is working overtime to develop solutions for a new generation of offshore floating windfarms. Because of the rapid proliferation of floating windfarms, it is unlikely that the rate of innovation by the crane industry will be allowed to slow. According to the International Energy Agency’s forecasts for offshore windfarms and vessels, Offshore Wind Outlook 2019, global offshore wind capacity is anticipated to reach 560 GW by 2040 for a total investment of US$840Bn. And most of that new capacity will come from Europe, with 175 GW followed by China (65 GW) and the US (22 GW).
As class society ABS explains in a 2021 report, demand for vessels including the all-important wind turbine installation platforms “is expected to increase to support planned construction projects for both fixed and floating offshore windfarms in US waters.” In America, fixed wind turbines are forecast to dominate on the US east coast, while floating versions will be concentrated in California and Hawaii.
Innovation for the US market
In response to a flurry of questions about the problems incurred by the ever-increasing height of cranes, panellist Shannon Galway, vice-president of technical services at US-based design group Friede & Goldman, better known for its offshore oil drilling rig designs, explained its latest innovation. Dubbed the BargeRack, it is a solution to the complexities of the Jones Act-mandated feeder system for installing offshore wind turbines. And it is different from other windfarm installation vessels.
“Our goal has been to think outside the box and come up with innovative ways to solve problems that the industry is seeing,” he told the audience, citing the Jones Act as a major preoccupation for Friede & Goldman. For background, the legislation defines a bottom-founded (or fixed) turbine foundation as a port. This means that internationally-flagged ships such as wind turbine installation vessels are only permitted to operate at a project site – for instance, by lifting components off a feeder vessel – provided they remain stationary. Therefore, the components must be shipped to the site by a US-built, US-flag feeder vessel.
“The question has always been how to get the components off the barge, the feeder that’s coming out,” explained Mr Galway. “And we feel like we’ve come up with a pretty ingenious way to do that by having a rack that is attached to the jack-up. We physically lift the barge up out of the water [which] has several advantages.
“Number one is that relative motions between the jack-up and the barge are completely eliminated. So, we don’t need any expensive motion-compensation equipment. We don’t need a fancy deck barge that has 3D motion compensation. We don’t need a separate jack-up vessel on location,” he said.
A big bonus of the concept, he added, is that “any dumb barge” serves the purpose because all the relevant equipment is on the wind installation vessel. “Our goal has been to use the existing barge fleet,” he went on. “The jack-up vessel can be built outside of the United States and does not need to be Jones Act-compliant. So that lowers capex. The barges would need to be built inside the United States but there’s plenty of them around already and they’re fairly simple to build.” The BargeRack could handle turbines up to 20 MW.
“On top of a runaway increase in size, the industry is being stretched to the limit in other areas”
Friede & Goldman’s engineers are also preoccupied with reducing the size of the crane boom. As Mr Galway underlined, it is the boom that determines the size of the vessel: “Once the vessel gets big, everything gets expensive. And it’s just like this never-ending loop of expense. If we can make the boom shorter, we can make the vessel shorter and lighter. Everything gets cheaper.”
In the US as elsewhere, the windfarm industry is hungry for innovation. In another poll, 63% of respondents said the best way to operate a 3D-compensated lift in the future would be remotely from a bridge, rather than from a crane cabin (just 1% suggested from shore). In a similar vein, a majority of respondents voted for “more speed in actions to preserve the world for the next generation.”
Wilco Stavenuiter, founder of Rotterdam-based start-up Tetrahedron, which has begun working with Friede & Goldman, may have part of the answer. He told the audience that his unconventional design will lift wind-turbine components – towers, blades and nacelles – up to 50 m higher than conventional cranes. “Wind turbines are getting higher and higher,” he explained. “The next generation of 12-14 MW turbines will require lifting heights of 180 m above sea level.”
So how does the Tetrahedron work? Shaped like a 3D triangle, it is designed specifically for wind turbines that, because they are slender, put a premium on height rather than reach. The essential calculations of the static and dynamic loads are done in a few minutes by proprietary software, he added.
Tetrahedron has already passed through the classification hoops with DNV and, Mr Stavenuiter told the audience, the three year-old start-up is involved in discussions with several potential customers who would pioneer the technology on an existing jack-up vessel.
For long-established shipping solutions provider MacGregor, some of the most important considerations are weight, ease of operation and safety. As Sindre Halvorsen, the group’s customer innovation manager for offshore energy solutions, said: “The main goal is always to make the lift operation as safe as possible for the operator – and it should be easy.”
The group’s latest crane is the Colibri, a 3D motion-compensated design developed for a long service life in the harsh conditions of the North Sea. The Colibri is based on a concept developed with Ulstein, which reduces the compensated mass to a minimum so that less power is used and motion is diminished.
What is not diminishing is the demand for new offshore cranes. Ms Roodenburg reported orders are coming thick and fast for record-breaking cranes. With 305 cranes delivered already, the Netherlands-based manufacturer has 20 cranes on order, of which nine are leg-encircling designs (LEC) specific for the wind industry. Over 142 of Huisman’s cranes to date are electric and Ms Roodenburg noted: “This demand is growing significantly because we’re working in the renewable industry.”
Backing up her observations about rapid development, Huisman’s run of orders in 2021 alone include a 1,600 mt LEC for jack-up vessel Sea Installer owned by offshore energy specialist DEME, a 2,600 mt LEC for Eneti’s new wind turbine installation vessel, and a 2,200 mt LEC for Charybdis, Dominion Energy’s wind turbine installation vessel.
Almost every contract sets new records. The Eneti order will result in a crane with a 147-m long boom capable of reaching 170 m above deck. The 2,600 mt lifting capacity means the crane will be able to install the next generation of 20 MW turbines. As a measure of the projected growth of the offshore wind turbine industry, the contract also provides for the option of a second crane that would be installed on another installation vessel.
Responding to the demand for increasingly powerful cranes, Huisman has been forced to double the slew-bearing production capacity of its facility in Schiedam, the Netherlands. Large-diameter slew bearings are a key component of heavy-lift cranes.
It is not just about power and reach though. The 2,600 mt crane is electrically driven, which allows crews to position it more accurately while using less energy, reducing maintenance and increasing reliability, the company points out. Meanwhile the all-important booms are becoming lighter and stiffer, the latter being important for reducing motion at the tip of the crane.
There is no doubt that the wind industry expects much from the crane industry. Asked in a poll what the biggest challenge currently facing the wind industry is, a third of respondents voted for “actual operation” while 38% said their problem was “finding reliable equipment for the right price and delivery time”.
As the panellists collectively made clear, expectations from clients will rise proportionately with the power of turbines. Asked where their size will stabilise, no less than 43% in a poll predicted a ceiling of 25 MW, while exactly the same percentage opted for 20 MW. To put this into perspective, as Mr Galway noted, a few short years ago even 10 MW was considered impossible.
© 2023 Riviera Maritime Media Ltd.