LCA Vestas_V80

Titel: Life Cycle Assessment of offshore and onshore sited wind farms (LCA Vestas_V80)
Författare/Author: Elsam Engineering A/S
Utgivare/Publisher: Vestas wind systems A/S
Årtal/Year: 2004
Sökord: Life cycle assessment, LCA, Horns Reef, Tjæreborg, environmental impact
Rapport via Vestas wind systems A/S


Sammanfattning/Summary: This report makes up the final reporting for the project “Life cycle assessment (LCA) of turbines – Analysis of possibilities of product directed environmental optimisation” effected by Elsam Engineering A/S and Vestas Wind Systems A/S financed by Elsam Engineering’s work through the Danish Energy Authority’s energy research programme for year 2000 (ERP2000). Vestas Wind Systems A/S financed its own participation in the project.

The purpose of the project is to carry through a life cycle assessment of an offshore wind farm and an onshore wind farm, respectively, as a basis for assessment of environmental improvement possibilities for wind farms through their life cycles.Likewise, the results are used to elaborate an environmental declaration of contents for power delivered to the grid from both types of wind farms.

The project has been running concurrently with a project about environmental assessment of future turbines, which RISØ is carrying out.Due to similarities between the two projects and the fact that RISØ’s project supplements the LCA-project in more ways, cooperation about the projects has been going on through the process, in the form of exchange of experiences and results. In cooperation with RISØ, Elsam Engineering and Vestas Wind Systems A/S have carried through a workshop about dismantling and removal of wind farms. In that connection, we would like to address our gratitude to RISØ for their help in planning and carrying out the workshop.

The project states the environmental impact for electricity produced at Horns Reef offshore wind farm and Tjæreborg onshore wind farm, respectively, as representatives for contemporary Danish offshore wind farms and onshore wind farms, respectively. Tjæreborg onshore wind farm is placed at an utmost favourably location with regard to wind, which means that the production at this wind farm is high compared with other onshore wind farms in Denmark. The high production rate is a factor that is taken into account when assessing the impact on the environment emanating from this wind farm.

The results of the environmental life cycle assessments that have been carried out for the two wind farms do not show significant variance. If it is taken into account that Tjæreborg onshore wind farm is placed utmost favourably, the comparison shows that power from an average located onshore wind farm would have a more adverse or corresponding environmental impact as an unfavourably located offshore wind farm.

The results show that it is the turbines that causes the largest environmental impact and not to a very high extent the transmission grid. For the turbines, the all-important environmental contribution comes from manufacturing and removal of the turbines, as it is the materials that cause the large environmental strain. The operation of the wind farms gives practically no contribution to the total environmental impacts. The foundations of the offshore wind farms make up a considerable factor to the total environmental impacts, as steel is a large constituent part of the foundations, some of which is abandoned at the seabed after dismantling of the farm. Therefore, the foundation of the offshore wind farms is selected as a focus area in connection with possibilities of product optimisation. Other types of foundations are assessed, and it is found that all the assessed foundation types give the same environmental impact, even though one of the types (caisson) will be completely removed from the seabed whereas in the case of other types (mono pile and tripod) everything more than 1 metre below the seabed is abandoned.