extended life-cycle assessment for offshore wind power

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Extended life-cycle assessment for offshore wind power

Anders Arvesen, Åsa Grytli Tveten, Edgar Hertwich, Anders Hammer Strømman

The Industrial Ecology Programme, Norwegian University of Science and Technology (NTNU)

European Offshore Wind 2009 Conference & Exhibition

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Wind power in a life-cycle perspective

End-of-life

Electrical connections

Wind turbine

Installation

Wind farm

O&M

Use

Network expansion

Tower

Cabling

Nacelle

Rotor

Substructure

Transformer

Iron

Steel

Aluminium

Copper

Concrete

Glass fibre

Electricity to grid

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Wind power in a life-cycle perspective

• The absence of in-plant combustion does not in itself justify claims of wind power as a ”clean” technology

• Life-cycle assessment (LCA) can assist in:– Developing system designs and strategies for a truly sustainable

wind power industry– Documenting the technology’s superiority over competing options

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Contents

• BackgroundReview of LCA literature• Environmental input-output analysis• Conclusions

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Review of LCA literature

Review of 28 estimates originating from 18 studies

• Published in 2000-2009– 14 studies published in scientific journals– 2 studies by wind turbine manufacturer (Vestas)– 1 in LCA commercial database (Ecoinvent)– 1 EU-funded research project (ECLIPSE)

• Turbine sizes < 500 kW excluded

• 8 estimates for offshore wind farms

• Mostly European conditions

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Life-cycle energy and global warming impacts for wind power

Energy intensity (kWhin/kWhel)

Global warming (g CO2/kWhel)

Onshore sites Offshore sites All sitesMinimum value 0.014 0.029 0.014Maximum value 0.082 0.054 0.082Average 0.037 0.041 0.038

Onshore sites Offshore sites All sitesMinimum value 4.6 5.2 4.6Maximum value 19.8 22.0 22.0Average 10.2 12.0 10.8

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Comparing offshore wind with natural gas combined cycle

Wind power versus NGCC:+ Small global

warming impact÷ Greater toxicity

impacts? Marine ecotoxicity

impacts

Source: Weinzettel, J., M. Reenaas, C. Solli, and E. G. Hertwich. 2009. Life cycle assessment of a floating offshore wind turbine. Renewable Energy 34(3): 742-747

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Influencing factors• Capacity factor: 19 – 54 %

– Onshore average: 29 %– Offshore average: 43 %

• Lifetime: 20 years

• Country of manufacture

• Assumptions on recycling of metals and blade material– Large differences between studies

• Offshore sites– Increased material and energy requirements– Improved wind conditions

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Analysis at component level

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Analysis at component level

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Do LCA studies provide the “full picture”?• In short: No

– Noise and visual effects: Generally disregarded– Effects on bird and marine life: Disregarded– Marine ecotoxicity: Lack of evaluation method– System changes: Generally disregarded

• However:– All but one study calculate CO2

– 2/3 studies calculate non-GHG emissions– Several studies cover a range of environmental impact categories

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Contents

• Background• Review of LCA literatureEnvironmental input-output analysis• Conclusions

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What is input-output analysis?

• Economic method used to analyze the industry relationships in an economy

• System of linear equations representing monetary flows

• Developed by Wassily Leontief in the 1930s

• Resurgence due to environmental applications

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How is input-output analysis relevant for LCA?

• Complete system coverage– Possibility for tracking all repercussions in the economy

• Generic data as proxy for process-specific data

• Drawback: High aggregation levels

• Hybrid IO/LCA: Exploiting the advantages of both methods

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Preliminary IO calculations

Data and assumptions

• Multi-regional input-output model– 64x64 IO tables for 23 European countries– 57x57 IO tables for 8 rest of the world regions

• Cost assumptions of offshore wind power– Investment costs: 2200 €/kW– Capacity factor: 38%– Lifetime: 25 years– Variable costs: 1.5 €cent/kWh– Cost breakdown based on external cost studies

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Preliminary IO calculations

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Conclusions

• The reviewed LCA studies agree that wind power does indeed represent a clean alternative to fossil power– Applies to onshore and offshore wind farms alike

• Recycling of metals and blade material may yield considerable emissions savings and reduce waste

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Conclusions (2)

• System changes should be taken into consideration– Grid upgrades– Altered operation of thermal plants

• Assessments can be further developed using IO techniques– Avoid truncation errors– Trace all economic repercussions

• Marine ecotoxicity: Inadequately investigated

extended life-cycle assessment for offshore wind power

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