investigating the potential for platform cost reductions · ungraded . 21 january 2016 ....

DNV GL © 2014

Ungraded

21 January 2016 SAFER, SMARTER, GREENER DNV GL © 2014

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21 January 2016 M. Kvittem, A. Steinert (TUHH), M. Ebbesen, D. Merino

ENERGY

Scaling up floating wind

1

Investigating the potential for platform cost reductions

DNV GL © 2014

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21 January 2016

Agenda

Introduction

Optimisation tool

Case studies

Results: Costs

Results: Optimisation

Conclusions

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Introduction

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Cost Reduction for Offshore Wind

Our promise to the industry:

Do things RIGHT

Do things BETTER

Do things DIFFERENTLY

“DNV GL is committed to help drive the commercialisation of floating wind power technology”

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Technically ready does not mean it’s commercial

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Source: http://arena.gov.au/files/2014/02/Commercial-Readiness-Index.pdf

Floating Wind

Onshore Wind

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Optimisation tool

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Motivation

What are the cost drivers for floating wind turbines?

How does a platform scale with larger turbines?

What is the impact of various turbine parameters on the platform design?

– Tower top mass

– Maximum thrust force

– Hub height

How to change the geometry of the platform to obtain a cost-optimized structure?

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Semi-submersible optimisation

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Iterates through a large space of variables:

– Column diameter

– Column spacing

– Draught

– Heave plate size

Constraints for the design:

– Surge, heave and pitch periods

– Maximum static tilt in operation

– Maximum dynamic tilt in survival

– Maximum tower base bending moment

– Nacelle acceleration

Cost rates per steel mass unit based on type of structural element

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Optimisation tool

18/01/2016

Developed in collaboration with master student Alexander Steinert

Optimisation with respect to unit cost

Parameter influences

Turbine rating influence 0 Optimisation

loop

Environmental condition Turbine properties

Optimal solution Parameter influences

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Particle Swarm Optimisation (PSO)

Find: Optimal solution ( )

– Minimise cost (objective function)

– Satisfy design criteria (constraints)

Stochastic process

1 swarm particle = 1 Platform

18/01/2016

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Current limitations

Currently only tested for a semi-submersible type floater

Linear or linearized theory

Limited structural check

No fatigue limit state

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Case studies

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Scaling up platforms for 10 and 20 MW turbines

Extreme wind speed: 50 m/s

50 year significant wave height: 18 m

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Platform optimisation for different turbines

Environmental Condition

50-year event

Location: West of Norway

– 𝐻𝐻𝑠𝑠 = 10.96 𝑚𝑚

– 𝑇𝑇𝑃𝑃 = 11.06 𝑠𝑠

– 𝑈𝑈10 = 39.49 𝑚𝑚𝑠𝑠

Turbines

Adapted for floating support structure

– Reinforced tower base

Scaled thrust force, based on NREL turbine using rotor swept area

NREL FORCE DTU Rating 5 MW 7 MW 10 MW

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Results: Cost

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Support structure cost

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60% increase in cost from 10 to 20 MW.

0.0

5.0

10.0

15.0

20.0

25.0

10 MW 20 MW

Mill

ion

EU

R

Anchors

Mooring lines

Secondary steel

Heave plates

Bracings

Column

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Cost development

With slenderness ratio Without slenderness ratio

Cos

t [M

illio

n €]

Cos

t [M

illio

n €]

Cos

t pe

r M

W

[Mill

ion

€/M

W]

Cos

t pe

r M

W

[Mill

ion

€/M

W]

5 7 10 [MW]

1.8

1.6

1.4

16

12 8

8

6

1.2 1

0.8

5 7 10 [MW]

5 7 10 [MW]

5 7 10 [MW]

Steinert, 2015, Master thesis TUHH

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Resulting optimal solutions

18/01/2016

Steinert, 2015, Master thesis TUHH

NREL 5 MW FORCE 7 MW DTU 10 MW Column diameter [m] (DC) 6 9 11 Heave plate diameter [m] (DHP)

15 22 25

Draft [m] 15 22 29 Platform radius [m] (R) 41 60 62 𝐃𝐃𝐇𝐇𝐇𝐇 𝐃𝐃𝐂𝐂⁄ 2.5 2.4 2.3 𝐑𝐑/𝐃𝐃𝐂𝐂 6.8 6.7 5.6

NREL 5 MW FORCE 7MW DTU 10 MW

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Observations

Numerical optimisation is a useful tool for initial assessments

Column spacing prevailing parameter

Sensitive to structural component type prices

Structural design should be included in the optimisation loop

Will the cost per MW go down with increasing turbine size?

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Industrialisation of floating wind – IN-FLOAT

- Large potential for cost reduction through industrialisation

- Large potential for learning from onshore wind towers

- Large opportunities with bolted connections, casted nodes, and lightweight modules

- Expanded supply chain – increased competition

Open source concept. Improve it!

investigating the potential for platform cost reductions · ungraded . 21 january 2016 ....

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