Development of a collision impact indicator to integrate in the life cycle assessment of offshore wind turbines

Development of a collision impact indicator to integrate in the life cycle assessment of offshore wind turbines

Life cycle assessment (LCA) is a robust approach to estimate the environmental impacts of an offshore wind farm (OWF). However, methodological hurdles remain, particularly the lack of appropriate indicators to assess ecosystem impacts during OWF construction and operation and the scarcity of marine ecological data. To address the lack of indicators, this article focuses on developing an impact indicator specifically related to bird collision with OWFs.

Collision Impact Assessment

Birds are among the taxa most widely affected by offshore wind energy through either attraction or aversion caused by the structures. Collision with wind turbine blades is expected to lead to the highest bird mortality and is one of the most controversial and publicly discussed impacts of wind electricity production in general. Yet, quantified information on potential collision impacts remains limited, with studies mainly based on observation data from ships, aircraft, and radar, which are expensive, time-consuming, and difficult to generalize.

Collision Indicator Development

To assess bird collisions during the operation of OWFs, we adapted a life cycle impact indicator originally developed for onshore wind farms. This indicator combines spatial data on bird species distribution and vulnerability to collisions with OWF technical characteristics (number of turbines, power production, rotor diameter). The results model and map seabird collisions at OWF worldwide and introduce a biodiversity impact characterization factor into LCA. The resulting characterization factors (CFs) are expressed as the potentially disappeared fraction of species (PDF) annually per gigawatt-hour (GWh) and vary between 2.0e−15 and 1.69e−13 PDF.year/GWh.

Integration with Life Cycle Assessment

Despite recent efforts to include an increasing number of impacts in LCAs, only a few studies consider the direct environmental impacts occurring during the operation phase of OWFs, and none exists that estimates the impacts of OWF on birds due to collisions. Our study aims to develop spatially explicit CFs to include the potential impacts of OWF on birds due to collisions in LCA studies. These CFs can be used to evaluate the current and future OWF impacts on bird species’ richness for different regions in the world.

Collision Impact Factors

Environmental Considerations

The spatial differentiation of the CFs highlights the OWF collision impact variability worldwide. Such mapping is crucial for identifying areas with varying levels of risk, which is essential for the strategic planning of OWFs. Projections indicate higher potential collision risks in Asia than in Europe, and future expansion of the OWF into new regions with higher collision potential is expected to increase collision risks.

Structural Integrity

The PCA analysis reveals that the most effective strategy for managing collisions appears to be, in order of priority, reducing the number of turbines, then minimizing their size, and finally, situating the OWFs farther from the coastline. These parameters, related to the structural integrity and operational performance of the OWF, are key factors influencing the collision impact.

Operational Performance

The results also show that the highest potential collision impact is calculated for the largest OWF projects, with more than 300 turbines each and producing between 2.4 and 3.6 GW. This indicates that while increased operational performance may be desirable, it can also lead to higher collision risks that must be carefully considered.

Life Cycle Stages

Manufacturing

The development of large-scale OWFs involves biodiversity impacts that are currently not accounted for in LCA, particularly during the operational phase. Our study provides one of the first assessments of the ecosystem impacts on the biodiversity of OWF during this phase.

Installation

The spatial CFs developed in this work could serve to identify at-risk areas and species to be considered in environmental management, in order to reduce the global impacts of offshore wind technologies during the installation phase.

Operation

The collision indicator focuses specifically on the operational phase, as it is expected to lead to the highest bird mortality. Modeling disturbance and habitat loss for marine bird species during other life cycle stages remains challenging due to the lack of data on habitat preferences and land-use models for the marine environment.

Decommissioning

While the decommissioning phase of OWFs may also impact biodiversity, this study concentrates on the operational phase, which is the focus of the newly developed collision indicator.

Sustainability Metrics

Energy Efficiency

The CFs are expressed per unit of energy production (GWh), allowing the assessment of the energy efficiency of different OWF designs and layouts in terms of their collision impact.

Environmental Impact

The collision impact indicator provides a valuable tool to evaluate the environmental impact of OWFs and identify the most sustainable solutions, considering both the energy production and the preservation of biodiversity.

Economic Viability

By integrating the collision impact into the LCA framework, this work contributes to a more comprehensive assessment of the economic viability of offshore wind energy, considering the trade-offs between electricity production and environmental conservation.

Multidisciplinary Approach

Structural Engineering

The findings highlight the need for a multidisciplinary approach, involving structural engineering expertise to optimize turbine design and layout, as well as environmental science to assess the biodiversity impacts.

Environmental Science

The development of the collision indicator required a deep understanding of avian ecology, species distribution, and vulnerability to collisions, demonstrating the importance of environmental science expertise in the assessment of renewable energy technologies.

Cost-Benefit Analysis

Ultimately, the integration of the collision impact indicator into the LCA framework allows for a cost-benefit analysis that can support decision-makers in the strategic planning and development of offshore wind energy, balancing energy production and environmental conservation.

The European Future Energy Forum provides a valuable platform to discuss the development of such multidisciplinary approaches to ensure the sustainable growth of the offshore wind sector in Europe and worldwide. ​By addressing the collision impact on birds, this study contributes to a more comprehensive understanding of the environmental implications of this promising renewable energy technology.

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