Pre-assembly of turbine components in Esbjerg assisted a 25 percent decrease in installation time and a clean safety record for the Kårehamn wind farm project. But that was just the beginning. We asked MHI Vestas Offshore Wind to tell us more about its pre-assembly capabilities today – and its plans for tomorrow.
Michael Rud, Head of WTG Logistics & Pre-assembly at MHI Vestas Offshore Wind, leads one of the most effective efforts to drive down the Levelised Cost of Energy at his company by cutting the costs of offshore installation. Trained in business rather than engineering, he maintains a 360-degree view on the opportunities to make the assembly, testing, loading and transport of turbine components faster and more efficient.
From offshore to the quay
Pre-assembly takes place at the quayside in the Port of Esbjerg in Denmark, where MHI Vestas Offshore Wind has built a dedicated pre-assembly site encompassing over 8,750 m2 of berth and some 55,000 m2 of fenced-off backland. Should more space be required, the company has a flexible, as-needed agreement in place with the port.
Today, for most of the company’s projects, as much of the installation work as possible is performed at the quayside facility rather than on the installation vessel out at sea. And there’s no shortage of benefits for keeping costs, complexity, and delays to a minimum.
Logistics galore
Pre-assembly is a textbook exercise in supply chain logistics. Nacelles, for example, arrive in Esbjerg with the hubs and drivetrains already mounted and tested. Cooler tops are added at the facility, as they would otherwise make the nacelle too large to transport by road.
The blades, too, arrive in a “plug-and-play” format. They arrive on site as individual components and are then stacked together in a single, impressively large structure carrying, in the case of the Humber Gateway project, 18 blades ready to be placed on six turbines that will be simultaneously loaded onto the vessel. This ‘blade stacker’ as it’s called, can be transferred with a single lift onto the vessel.
The towers are delivered to the pre-assembly site in two sections, which are then assembled and loaded onto the installation vessel as a single, up-right component. In order to reduce time at sea, the nacelle is tested and commissioned at the site before loading, to make sure all systems are ready to go as soon as the turbine is installed.
All cable routing on the towers and all mechanical systems are also put in place at the pre-assembly facility. Additional efficiencies are achieved through the use of specialised equipment, including a lifting tool that can handle both towers and nacelles, removing the need to change tools between the different component types.
Together, these methodologies contribute to a straightforward solution that successfully reduces offshore installation time and costs.
Stellar results
Right from the outset, MHI Vestas Offshore Wind’s business case clearly indicated that the new approach would not only prove cheaper in the long run, but it would bring additional advantages through HSE, quality standardisation, and ease of access to necessary resources.
“There’s a lot of flexibility in having all of our suppliers located close by,” says Michael Rud. “That makes it much easier to get access to tools, replacement components and other specialised items whenever we need them.”
The Kårehamn wind farm project, although it was the first to be pre-assembled at the facility, was already a showcase in efficient logistics management. The project’s installation time was cut by 25 percent, simultaneously delivering a safety record of zero lost-time injuries. And this early success has been followed by impressive savings on subsequent projects as operations have been further refined.
Smooth operator
Working with pre-assembly demands meticulous planning and coordination. For example, the Esbjerg site most often works on a just-in-time basis where components arrive and enter the assembly process straight away. Handling is minimised, and with production lines just 80 kilometres away, MHI Vestas Offshore Wind has the flexibility to deal with unexpected challenges.
Initially set up by the travelling technicians, the Esbjerg site keeps around 60 personnel busy – 45 of whom are sub-contractors.
“We have many highly specialised teams, each of which has become skilled at ensuring rapid turnaround on each component,” says Michael Rud. “It’s an exaggeration, of course, but we like to say that these days, our teams could almost assemble their components in the dark.”
The road ahead
The current pre-assembly site is designed to handle the company’s V112-3.0 MW turbines, and there is an option to scale up the site to work with larger turbines.
“All the V112 projects have been executed out of Esbjerg and we expect this to continue going forward,” says Michael Rud. “It’s definitely possible to scale up the site to handle larger components using different hardware should we decide to do so.”
“The overall strategy is to move as much of the process from offshore to port, and even better, to the PBU (Production Business Unit Ed.). That’s the mentality we have and we are very eager to innovate and do whatever we can to push the work back up the supply chain. This also assists safety and quality aspects.”
To date, the Esbjerg facility has been charged with pre-assembling and shipping a total of 161 turbines to the Kårehamn (Sweden), Northwind (Belgium) and Humber Gateway (UK) wind farms. Michael Rud says that there’s plenty more in the pipeline, but he issues a note of caution for achieving the full potential of pre-assembly activities in Esbjerg:
“We need a lot of flexibility when doing pre-assembly so we can work fast when the vessel comes in. That takes good communication and the right attitude among all of the people, companies and other parties involved. If one of the parties introduces delays they risk endangering the overall viability of the facility. Right now, we’ve still got a way to go on that front.”
What is pre-assembly?
In order to optimise the offshore installation process and keep safety risks at minimum, turbines are pre-assembled at a special facility located at the harbour in Esbjerg, Denmark. The turbines are pre-commissioned and configured before they are transported offshore, reducing commissioning hours at sea.
Like this post? Subscribe now and get notified about new content!