How to achieve assembly line fabrication of specific design

Henrik Carstens Projects & Technology Director Ramboll Offshore Wind

Agenda

•Background

•Mass Production

•Do’s and Donts

•Conclusions

Why am I here?

Ramboll have designed the foundations for 54% (1646MW out of 3058MW)

74% (2256MW out of 3058MW) is based on monopiles…….Why?

Cost per kilo – Identical Steel Price

~2 € per kilo ~5 € per kilo

The challengeFabrication

InstallationOperation

“To harvest the advantages of assembly line fabrication of wind turbine foundation structures designed to suit the varying soil conditions and water depths for large offshore windfarms while maintaining easy installation in most weather conditions as well as low O&M costs”

EWEA’s market development scenarios

•EWEA has three scenarios for offshore: low, reference and high, depending on the key criteria for offshore development.

•According to the reference scenario, there will be 3.5 GW of offshore wind in the EU in 2010, 35 GW in 2020 and 120 GW in 2030.

•Using an average turbine size of 5MW this corresponds to more than 600 foundations a year until 2020

Mass Production

“Mass production is capital intensive and energy intensive, as it uses a high proportion of machinery and energy in relation to workers. It is also usually automated to the highest extent possible. With fewer labour costs and a faster rate of production, capital and energy are increased while total expenditure per unit of product is decreased. However, the machinery that is needed to set up a mass production line (such as robots and machine presses) is so expensive that there must be some assurance that the product is to be successful to attain profits.”

Lack of investment in foundation fabrication

Bottlenecks in supply chain

Expensive Foundations

Targets not reached or expensive power

i.e. Nobody will invest unless they have a reasonable chance to get a return

Lack of long term commitment

Investment cost breakdown for offshore wind(IEA, 2008) – turbine is only half the cost (USD/MW)

Turbines, incl. transport; 1020; 47%

Transformer station and grid to coast; 340; 16%

Internal grid between turbines; 105; 5%

Foundations; 440; 21%

Environmental analyses; 75; 4%

Miscellaneous; 12; 1%

Design, project management; 125; 6%

Allow for sufficient design time

•To complete load iterations and optimize on primary steel weight

•Design based within limitations/capabilities of rolling mill:

• Single plate weight up to 23/28 tons, Max. width 3m/4.2m

•To standardise details

• To make automation of components possible

•To finalise design before fabrication starts

• The devil is in the detail

• Avoid changes by involving fabrication, installation and maintenance contractors in design phase

Allow for sufficient lead time•M

anufacturing can focus on efficiency & meeting schedule:

• No “fire fighting”

• No empty production shops or excessive overtime

•All materials for major secondary components can be supplied directly from rolling mills or from stock:

• Lower prices

• Exact lengths - No scrap or extension welds

•Necessary buffers between different production phases:

• Primary – secondary

• Prefab - secondary

• Secondary – installation

• Allowance for release of “prototypes”

Summary & Conclusions

•The continued development of offshore wind farms are going to require 600-1000 foundations per year until 2020

•Deeper water and bigger turbines requires serial fabrication of foundation structures to keep costs down

•Lack of long term commitment holds back investments in foundation fabrication automation

•Insufficient time leads to higher costs due to un-optimised design, higher material costs and higher risks

•Foundation optimisation for serial production is decided at the design stage