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Life cycle assessment of electricity production from airborne wind energy
Citation Link: https://doi.org/10.15480/882.1302
Publikationstyp
Master Thesis
Date Issued
2015-08
Sprache
English
Author(s)
Advisor
Referee
Title Granting Institution
Technische Universität Hamburg
Place of Title Granting Institution
Hamburg
Examination Date
2015-08
TORE-DOI
Global energy supply is closely linked with some of the greatest challenges of our society. A rising demand has to be met whereas conventional energy sources are depleting and emit considerable amounts of greenhouse gases. Renewable energy technologies are increasingly promoted to face these issues, especially in the electricity industry. Research has shown, that renewables are superior to conventional energy technologies in many environmental aspects but are not free of burdens. However, the main causes of impacts are shifted to other life cycle phases than operation. The emerging of airborne wind energy
(AWE), as a new stakeholder within the renewables, presents an ecologically promising option since it accesses wind resources of outstanding quality with little material consumption. As of now, there is no environmental assessment of this new technology available. The goals of this study are (1) the determination of environmental burden of electricity generation with AWE on the categories global warming and consumption of energy resources, (2) the identification of main contributors to these categories, (3) the determination of the energy payback time and (4) an assessment whether use of this technology would lower impact of electricity supply in the mentioned categories. An AWE design is chosen for the investigations, which appears possible to become a dominating design. Even though uncertainties arise from the analysis of a specific design, the outcomes of the study could serve as a first reference for system developers and for decision-makers to evaluate support or engagement in this technology.
To this end, a life cycle assessment (LCA) was executed, which allows tracking of category indicators from cradle to grave. Specific AWE facilities of 1.8 MW were defined and analyzed in a 300 MW plant under low wind conditions. The modeling follows an estimated dominating design or conservative choices. The results are expected to be on the upper range. The results of the model are presented and discussed and checked for robustness in a sensitivity study. A comparison to a similar conventional wind power plant and the electricity grid mix allows a better classification of the results. The category indicator result in global warming potential (GWP) is 5.611 gCO2-eq./kWh. 65 % of that occur in the phase raw material and manufacturing, 3 % during installation, 28 % during operation and 4 % in disposal. The cumulated energy demand (CED) is 75.2 kJ-eq./kWh. The invested energy during the entire life cycle is 2.1 % of the total generated electricity and is recovered after 5 months or 153 days of operation. This corresponds with an energy yield ratio of 48%. The tether accounts for 5.5 and 8.1 % in GWP and CED, including its replacements. Lower lifetimes have significant influence, higher are with marginal effect. The environmental effects from the wing manufacture arise by 75% from the carbon fiber reinforced polymer but are only 2.6 and 5.6 % in GWP and CED. The biggest contribution is from generator and gearbox, which account for 35 and 30 % in GWP and CED respectively, including replacement of all gearboxes. In total, 30 % of the impacts come from balance of station components and 70 % from the AWE facility. The latter is the percentage that the system developer can influence directly. Compared to a conventional wind plant that was modeled in a similar way, the AWE plant consumed 23 % of the mass, causes 49 % of the GWP and consumes 55 % of the CED. Energy payback time was 2 times lower. Compared to German electricity mix the plant causes 0.87 % of the GWP and has 0.74 % of the CED. Even with a conservative approach the study confirms the expectation of low impact in the considered categories and presents first numerical results.
(AWE), as a new stakeholder within the renewables, presents an ecologically promising option since it accesses wind resources of outstanding quality with little material consumption. As of now, there is no environmental assessment of this new technology available. The goals of this study are (1) the determination of environmental burden of electricity generation with AWE on the categories global warming and consumption of energy resources, (2) the identification of main contributors to these categories, (3) the determination of the energy payback time and (4) an assessment whether use of this technology would lower impact of electricity supply in the mentioned categories. An AWE design is chosen for the investigations, which appears possible to become a dominating design. Even though uncertainties arise from the analysis of a specific design, the outcomes of the study could serve as a first reference for system developers and for decision-makers to evaluate support or engagement in this technology.
To this end, a life cycle assessment (LCA) was executed, which allows tracking of category indicators from cradle to grave. Specific AWE facilities of 1.8 MW were defined and analyzed in a 300 MW plant under low wind conditions. The modeling follows an estimated dominating design or conservative choices. The results are expected to be on the upper range. The results of the model are presented and discussed and checked for robustness in a sensitivity study. A comparison to a similar conventional wind power plant and the electricity grid mix allows a better classification of the results. The category indicator result in global warming potential (GWP) is 5.611 gCO2-eq./kWh. 65 % of that occur in the phase raw material and manufacturing, 3 % during installation, 28 % during operation and 4 % in disposal. The cumulated energy demand (CED) is 75.2 kJ-eq./kWh. The invested energy during the entire life cycle is 2.1 % of the total generated electricity and is recovered after 5 months or 153 days of operation. This corresponds with an energy yield ratio of 48%. The tether accounts for 5.5 and 8.1 % in GWP and CED, including its replacements. Lower lifetimes have significant influence, higher are with marginal effect. The environmental effects from the wing manufacture arise by 75% from the carbon fiber reinforced polymer but are only 2.6 and 5.6 % in GWP and CED. The biggest contribution is from generator and gearbox, which account for 35 and 30 % in GWP and CED respectively, including replacement of all gearboxes. In total, 30 % of the impacts come from balance of station components and 70 % from the AWE facility. The latter is the percentage that the system developer can influence directly. Compared to a conventional wind plant that was modeled in a similar way, the AWE plant consumed 23 % of the mass, causes 49 % of the GWP and consumes 55 % of the CED. Energy payback time was 2 times lower. Compared to German electricity mix the plant causes 0.87 % of the GWP and has 0.74 % of the CED. Even with a conservative approach the study confirms the expectation of low impact in the considered categories and presents first numerical results.
Subjects
LCA
Life Cycle Assessment
AWE
Airborne Wind Energy
DDC Class
620: Ingenieurwissenschaften
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Name
LCA of Electricity Production from AWE - masters thesis Stefan Wilhelm.pdf
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5.22 MB
Format
Adobe PDF