December 2009

Challenge the future

DelftUniversity ofTechnology

The Delft Offshore Wind Turbine Concept (DOT)

Antonio Jarquín Laguna

A hydraulic solution for offshore wind energy

2The Delft Offshore Wind Turbine Concept (DOT) | 16

Table of Contents

• Current turbine technology

• Delft Offshore Turbines

• Hydraulic energy transfer

• Overview DOT project

• Preliminary results

• Conclusions

3The Delft Offshore Wind Turbine Concept (DOT) | 16

Current Turbine Technology

General

• Danish concept (3 blades)

• Heavy nacelle

• Huge gearbox + big generator

• Huge amounts of switch gear

Many components

�many failures

� high maintenance

Offshore

• Difficult installation

• Difficult maintenance

� Not yet cost effective without government subsidies

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Delft Offshore Turbines (DOT)

TU Delft: step away from incremental improvements

�Design turbines specifically for offshore

Two main drivers:

• Size

• Cost of energy

So, let us start by… ?

5The Delft Offshore Wind Turbine Concept (DOT) | 16

Delft Offshore Turbines (DOT)

Everything out of the nacelle!

So, we only have:

• rotating kinetic energy• a point to deliver electrons

� Everything in between is for us to design

?

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Power Transmission

• Current systems:

• High top-mass• High cost of components• Dynamic loads• High maintenance

• Solution?

� use hydraulic power transmission: we pump!

Delft Offshore Turbines (DOT)

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Hydraulic energy transfer

Hydraulic Wind Turbines

• Advantages

• Gearless transmission

• More robust than mechanical

gearboxes

• High power-to-weight ratio

• Damping of dynamic loads

• High reliability/Low maintenance

• Challenges

• High efficiency

• Seawater as hydraulic fluid

• Wide operational range (!)

• Vital components not available

(Scaling effects)

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Overview DOT

Fixed displacement

pump

-No need of control without

significant loss of efficiency

- ηvol can be improved (internal seals and

scaling effects)

Fixed displacement

motor

Variable displacement

pump

-No need of control, high efficiency

-Control to get high performance

with high pressures and low flows

-Constant pressure to allow

connection with other turbines

-Reduced friction losses

Seawater line

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Centralized electricity generation

Hydro Plant

Electricity to shore

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Centralized electricity generation

• Hydraulic turbines

• Hydro- power plants have the highest operating

efficiency of all known generation systems

• No need of dam or large reservoir

• Large capacities up to 400 MW per unit

• High efficiency at partial loads (>90 %)

• Onshore operation and control

• Largely automated (operating costs are relatively low)

• High Voltage

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Hydraulic wind developments

Current hydraulic wind developments(Hydraulic transmission)

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Preliminary Results

For a single turbine

• Comparable power

compared with a

commercial turbine

• Limited by rotor loads

No longer limited by Max torque of individual generators!!

0 2 4 6 8 10 12 14 160

2

4

6

8

10

12Powercurves

Wind Speed U [m/s]

Pow

er [

MW

]

PDOT single turbine

PRePow er 5 MW

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Preliminary Results

For 20x turbinesConnected in parallel

• Lower energy

production for low

wind speeds

• High potential for high

wind speeds

0 2 4 6 8 10 12 14 160

50

100

150

200

Powercurves Total

Wind Speed U [m/s]

Pow

er [

MW

]

PDOT

PRePow er 5MW W20x

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Preliminary Results

Efficiencies

• Main limitation driven

by the variable

displacement pump

performance

0 2 4 6 8 10 12 14 160

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1Energy transfer performance

Wind Speed U [m/s]

η

ηgenerator

0 2 4 6 8 10 12 14 160

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1Energy transfer performance

Wind Speed U [m/s]

η

ηgenerator

ηpiping

0 2 4 6 8 10 12 14 160

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1Energy transfer performance

Wind Speed U [m/s]

η

ηgenerator

ηpiping

ηclosed loop

0 2 4 6 8 10 12 14 160

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1Energy transfer performance

Wind Speed U [m/s]

η

ηgenerator

ηpiping

ηclosed loop

ηvarpump

0 2 4 6 8 10 12 14 160

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1Energy transfer performance

Wind Speed U [m/s]

η

ηgenerator

ηpiping

ηclosed loop

ηvarpump

ηFinal

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Conclusions

• Centralized electricity generation can be possible with hydraulics

transmission

• High potential for high wind speeds

• Further analysis in dynamics and control

• Economical study needed

• Challenges

• Seawater as an hydraulic fluid (wear and corrosion)

• Availability of components

A solution for large wind offshore

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es, we can!

Thank you!!

Questions…?

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General configuration

~

M

20x

300 bar

∆p up to 350 bar

High pressure

Low

pressure

Rotor

Pump 1

Motor

Pump 2

Seawater

Pelton

turbine

Synch

Generator

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Concept of the DOT energy transfer system

Mechanical

Energy

Hydraulic

Energy

Electrical

Energy

Wind

Energy (KE)

RotorWind SpeedT

ωHydraulic

Pump

p

Q

Generato

r

Platform

Electrical

power

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0 2 4 6 8 10 12 14 160.7

0.75

0.8

0.85

0.9

0.95

1Energy transfer performance

Wind Speed U [m/s]

η max

Fix Dp

Var Dp

Variable displacement pump

0 2 4 6 8 10 12 14 160

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2Volumetric displacement of the pump

Wind Speed U [m/s]

Dp [

m3 /r

pm]

0 2 4 6 8 10 12 14 160

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1Energy transfer performance

Wind Speed U [m/s]

η

0.05 Dpnom

0 2 4 6 8 10 12 14 160

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1Energy transfer performance

Wind Speed U [m/s]

η

0.05 Dpnom

0.10 Dpnom

0 2 4 6 8 10 12 14 160

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1Energy transfer performance

Wind Speed U [m/s]

η

0.05 Dpnom

0.10 Dpnom

0.15 Dpnom

0 2 4 6 8 10 12 14 160

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1Energy transfer performance

Wind Speed U [m/s]

η

0.05 Dpnom

0.10 Dpnom

0.15 Dpnom

0.25 Dpnom

0 2 4 6 8 10 12 14 160

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1Energy transfer performance

Wind Speed U [m/s]

η

0.05 Dpnom

0.10 Dpnom

0.15 Dpnom

0.25 Dpnom

0.50 Dpnom

0 2 4 6 8 10 12 14 160

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1Energy transfer performance

Wind Speed U [m/s]

η

0.05 Dpnom

0.10 Dpnom

0.15 Dpnom

0.25 Dpnom

0.50 Dpnom

1.0 Dpnom