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Delegates are invited to meet and discuss with the poster presenters in this topic directly after the session 'Advanced operation & maintenance' taking place on Thursday, 13 March 2014 at 11:15-12:45. The meet-the-authors will take place in the poster area.

Bastien Gaillardon Rescoll, France
Co-authors:
Blanca Palomo (1) F P Claire Michaud (1) Bastien Gaillardon (2) Sandrine Ausset (1)
(1) Rescoll, Pessac, France (2) Valeol, Bègles, France

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Presenter's biography

Biographies are supplied directly by presenters at EWEA 2014 and are published here unedited

Bastien Gaillardon graduated in Supaero, one of the best aerospace school in France. In 2009, he joined with Valeol, R&D subsidiary of the renewable energy Valorem Group, based in Bordeaux in France. He has been involved in several innovative projects on arodynamics, control and stucture of blades and wind turbines. He has also made on behalf of Valorem Group and in partnership with the company Rescoll, the LCA of a wind farm.

Abstract

Life cycle assessment of a French wind plant

Introduction

Although there are several analyses on the environmental impact of renewable energies, not many life cycle assessment studies exist for wind farms. Consequently, a Life Cycle Analysis model has been developed with the purpose of evaluating the potential environmental impacts associated with production of electricity from an onshore wind plant comprised of five 3.0 MW wind turbines from a life cycle perspective. The wind plant set-up stage has been described in detail and energy indicators have also been calculated. The LCA study was prepared by Rescoll in partnership with the Valorem-Valeol group.

Approach

This study was prepared in accordance with the methodological stipulations of the following standards: ISO 14040 and ISO 14044.

The main objectives of this study were:
Deliver a rigorous and impartial environmental assessment of the wind plant in Pauillac, France.
Describe the most favourable stages and the most impactful stages (from an environmental point of view) in order to identify optimization and improvement areas for technology and product development
Perform sensitivity analyses regarding the influence of the wind plant lifetime and of different end of life treatments of blades on the environmental profile of the Pauillac wind plant.

Primary data were collected from VALEOL and from their suppliers. When primary data were not available, secondary data were based on literature and were validated by VALEOL. These data have been complemented by generic data available in the Ecoinvent database.

This wind farm is considered a test wind farm. In fact, the final wind turbines will be different from a technical point of view.
We have simplified the system with the assumption that the system is composed of identical turbines. All data were collected during the year 2012. Indeed, as the wind plant is undergoing development, it was not possible to base the study on plant operation for a full year.

It is important to be able to compare the potential environmental impacts associated with electricity from a wind plant using specific turbines to other forms of electricity generation.

The functional unit of this LCA study was defined as:
1kWh of electricity delivered to the electrical grid.

Figure shows life cycle stages considered for assessing the environmental impact of the wind plant during its whole life cycle.

To assess the environmental impacts of the wind farm, we selected the following indicators of the CML method of calculation: abiotic resource depletion, acidification potential, global warming potential, photochemical ozone creation potential and eutrophication.
In order to assess the damage to ecosystems caused by soil occupation and transformation, we used indicators proposed by the ReCiPe 2008 method.
The Cumulative Energy indicator was also used to quantify renewable and non-renewable energy consumption.


Main body of abstract

This section describes results of the evaluation of the wind plant effects on the environment. The assessment was performed regarding eight environmental impact indicators, two sensibility analyses and Energy Payback Time (presented below).
On the whole life cycle of the wind plant, the production stage is the most significant regarding all the environmental impact indicators studied.
As shown in figure , the environmental analysis shows a dominant incidence of the manufactured moving parts on eight of nine indicators studied.
More specifically, the nacelle has the highest incidence on moving parts impacts. That can be explained by the fact that the nacelle is the second most heavy component of the wind turbine and is the most complex one.
Analysis of mass environmental impacts concentration showed that blades have a significant contribution compared to the tower (non-moving parts).
The tower makes up ~88% of the overall component weight while blades make up ~3%.
The set-up stage is the second most important of the whole life cycle. More specifically, foundations have a dominant incidence on 8 of 9 environmental impact indicators, mainly because they are the heaviest part of the wind turbine (1534 tons per foundation).

On the other hand, the study stage impacts of the wind plant life cycle are insignificant (between 0.003 and 0.033%).

The components transport stage from their plant site to the work site represents between 0.2% and 2.4% of global environmental impacts.

The operation stage accounts for 5.1 to 7.2% of all life cycle impacts and these impacts mainly come from component replacements.

The environmental burdens of dismantling stage are low, 0.2% to 1.1% of the whole life cycle impact.

Finally, it should be noted that regarding the land transformation indicator, the dismantling stage accounts for -34%, due to the tower being made of concrete. This negative value can actually be considered as a benefit to the environment, given that the landfill site is transformed into forest land after its closure.


Two sensitivity analyses were performed, varying the key parameters: initially the lifetime period and then the end-of-life scenario for the blades.

The first results (with a wind plant lifetime period = 20 years) were compared to a 40-year wind plant. It was considered that all parts have a lifetime period two times longer, except moving parts that still have a 20-year lifetime period.

Results for every indicator decreased between 9 and 26%. For five of the nine indicators studied, the decrease of global results was up to 20%.

Then, a second sensitivity analysis was performed for three different scenarios of blades end of life.

Scenario 1: landfilling. This scenario considers impacts resulting from landfilling with the components. This is the baseline scenario.
Scenario 2: materials recovery by a fine grinding process (from a few m to 15 mm). Grinded material can then be reused for different purposes: paving concrete, road paving, composite board for building sector, insulation materials, reinforcement materials for thermoplastic materials, etc. This scenario takes into account impacts resulting from the grinding process and gives “credit” for avoided burdens by reducing the primary production of gravel.
Scenario 3: energy recovery from high calorific value waste. This scenario takes into account burdens resulting from blade incineration giving “credit” for avoided burdens of an equivalent quantity of French electricity production.

As for the materials recovery scenario, the majority of environmental indicators shows a slight decrease compared to the baseline end of life scenario. In fact, avoided burdens regarding the primary production of gravel is insignificant.

Regarding blade incineration in the energy recovery scenario, beneficial effects can be observed for 7 of the 9 impact indicators. But, the greenhouse effect is four times higher than the baseline scenario because of greenhouse gas emissions.

An energy balance was calculated showing the relationship between the energy requirement for the whole life cycle of the wind plant and the power output from the wind plant. The energy indicator calculated as explained previously is called Energy Payback Time. Results regarding this indicator are shown in figure .


Conclusion

The main outcome of this study is an accurate and non-biased environmental assessment of the Pauillac wind plant in France. A special focus was realized on the construction stage since it directly concerns the activities of VALEOL. The use of the Life Cycle Assessment enabled the identification of the major impacts of the Pauillac wind plant throughout its whole life cycle.
As a main result, for each impact category investigated, the production stage of the different components of the wind plant, and more precisely the production of the moving parts, is the stage that shows the most impacts.
Secondary impacts come from the construction stage, with strong impacts linked to the building of the foundations on 8 of the 9 impact indicators. This is mainly due to the mass of the corresponding components.
The sensitivity analysis clearly highlighted that results are greatly influenced by the hypothesis of the wind plant life time. For instance, an increase of the life time from 20 to 40 years, taking into account the obligations for maintenance and replacement of parts, leads to a 20% decrease of the impacts as the impacts linked to the production of the different components depreciate over a longer period of time.
For the end of life, three scenarios were considered for the blades and no significant difference was observed between the materials recovery and the landfill approach. In the case of energy recovered from burning, there is an evident positive impact on the cumulative energy demand, however impact on global warming is 4 times higher compared to the reference scenario. In addition, impacts linked to the occupation of agricultural fields, photochemical ozone layer production, eutrophication, acidification and depletion of abiotic resources are substantially reduced.
Regarding qualitative indicators, the hypothesis on the life time of the plant showed a strong influence on the results since a decrease of 21% is observed for the Energy Payback Time indicator.



Learning objectives
Audience would learn from this conference results of a full life cycle assessment of a French innovative wind plant, energy payback time and how to improve wind plant ecoprofile.


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