author: anders moeller telephone: +45 20320142 e-mail: amo ... · transition piece, grout seal and...
TRANSCRIPT
Efficient offshore wind turbine foundations
24-09-2008 www.densit.com
Author: Anders Moeller
Telephone: +45 20320142
E-mail: [email protected]
Company: Densit ApS
Origin: Denmark
Efficient offshore wind turbine foundations
24-09-2008 www.densit.com
Introduction
l For centuries mankind has used wind resources for sailing.
l Today the use of wind includes power production from offshore wind turbines.
Headlines
• Turning offshore• Offshore wind turbine foundation structures• Monopile structures (75% of all installations to date)• Dimensions• Installation methods and tools• Transition piece, grout seal and grout method• Grout types and properties• Installation vessels and jack-ups•New methods and solutions for foundations at deeper water
• Closing
24-09-2008 www.densit.com
Turning offshore
In 1990 the first offshore wind turbine was installed in Nogesund Sweden, 1000 feet off the coast and at a water depth of 20 feet.
The turbine was a 210 KW Wind World stall regulated machine.
24-09-2008 www.densit.com
Foto: Mats Nying Svante I
Offshore wind turbine foundation structures
Rock drilled monopileDriven monopile with grouted transition piece Gravity foundation
24-09-2008 www.densit.com
UHPC
Grout pipe with three inlets Transition piece with tower flange Brackets with hydraulic jacks Grout seal Monopile
Monopile structures - Dimensions
Principle of driven monopile with grouted transition piece
msl
Pile sizes: 3-5,1 m (118-200 inch)
Overlap: 1,33 to 1,6 x pile outer diameter
Annuli: 50-125 mm (2-5 inch)
Water depth: 4-25 m (13-75 feet)
Penetration: 20-40 m (66-100 feet depending on soil)
24-09-2008 www.densit.com
Installation methods and tools
Jack-up crane barge loaded with monopiles and transition pieces
A2SEA - Sea Jack
24-09-2008 www.densit.com
www.a2sea.com
Installation methods and tools
Hammer size and drive force
The German manufacturer Menck is offeringhydraulic hammers for driving big monopilesin the below classes.
MHU Energy Weight Length
(KJ) (t) (m) (feet)
550S 550 135 13.8 45
800S 800 167.4 15 49
1900S 1900 292 23.2 76
24-09-2008 www.densit.com
Pile in drive gate with hammerin place
Installation methods and tools
Drive drill drive Two different applications for drilling inside the pile in order to drive the pile to final depth
24-09-2008 www.densit.com
Installation methods and tools
Installation of transition piece
24-09-2008 www.densit.com
Installation methods and tools
Connecting the grout hose from the pump at the batch mixing station to the inlet at the transition piece
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Installation methods and tools
Position for hydraulic Jack
Levelling of transition piece
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Transition piece, grout seal and grout method
The most common grout seal for these applications has been a lip type rubber seal. The company MT Hojgaard has tested and patented a solution which has performed outstanding. The grout is led to the bottom of the transition piece and normally distributed to 3 inlets placed just above the grout seal.
24-09-2008 www.densit.com
Grout types and properties
The most commonly used grout type is the ultra high performance Ducorit® S5 with a mean compressive strength of 18500 psi (130 MPa)
24-09-2008 www.densit.com
765432
10.90.80.70.60.5
0.4
0.3-10 0 10 20 30 40 50
Temperature °C
100
90
80
70
60
50
40
30
20
10
0
% Relative property
0.5 1 2 7 28 Days
Dur
atio
n fa
ctor
(= 1
AT
20°C
)
Elasticity
Flexural strength
Compressivestrength
Grout types and properties
Grout material, strength development Ducorit® S5 & D4
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Grout types and properties
Densit® versus good quality reference concrete
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Installation vessels and jack-ups
SeacoreA2SEA
A2SEA MPI
HSS
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MPI
HSSA2SEA
New methods and solutions for foundation at deeper water
Tripod Design Study where center transition piece is connected with high performance grout and thereby increasing capacity of welded joints.
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Tripod for the German project Alpa Ventus designed for 30 m water dept.
New methods and solutions for foundation at deeper water
24-09-2008 www.densit.com
New patented concept developed by the German company Bard Engineering. The three pile structure with a connecting structure grouted to the piles is designed for a 5 MW wind turbine
www.bard-engineering.de
New methods and solutions for foundation at deeper water
24-09-2008 www.densit.com
Piles installed for the three pile structure.
www.bard-engineering.de
www.bard-engineering.de
New methods and solutions for foundation at deeper water
24-09-2008 www.densit.com
The connecting structure is designed for a 5 MW wind turbine.
www.bard-engineering.dewww.bard-engineering.de
New methods and solutions for foundation at deeper water
24-09-2008 www.densit.com
The connecting structure in place ready to be grouted
www.bard-engineering.dewww.bard-engineering.de
New methods and solutions for foundation at deeper water
24-09-2008 www.densit.com
For deeper water a steel structures like OWEC Jacket Quattropod (OWEC Tower AS) can be selected as the foundation. The Jacket is secured with pile/sleeve connections.
www.bard-engineering.dewww.owectower.no
Closing
24-09-2008 www.densit.com
The offshore wind turbine part of the market is still only a fraction of the onshore installations. Until now approximately 2.000 MW have been built or are under construction.
Looking at the forecast for Europe this number will be passed by far during the next decade.
When moving to greater water dept. (30m+), it is important that all parts of the structures are made more cost effective. Alternatively new cost efficient methods are developed for deeper waters in order to make the offshore installations competitive.
Furthermore the wind turbines need to be more reliable because it is very costly to service and repair the turbines offshore.