Josefine Marx

Meta-Analysis of Life Cycle Assessment Studies on Electricity Generation with Carbon Capture and Storage

In the last decade, numerous life cycle assessments (LCAs) on environmental impacts of electricity generation with carbon capture and storage (CCS) have been conducted. This meta‐analysis comprises 15 LCAs of the three CCS technologies (postcombustion, oxyfuel, precombustion) with a focus on greenhouse gas reduction for different regions (Europe, United States, Japan, global), different fuels (hard coal, lignite, natural gas), and different time horizons (between the present and 2050). It presents a condensed overview of methodological variations, findings, and conclusions gathered from these LCAs. All LCAs show the expected reduction in global warming potential but an increase in many other impact categories, regardless of capture technology, time horizon, or fuel considered. Three parameter sets have been identified that have a significant impact on the results: (1) power plant efficiency and energy penalty of the capture process, (2) carbon dioxide capture efficiency and purity, and (3) fuel origin and composition. This meta‐analysis proves that LCA is a helpful tool to investigate the variety of environmental consequences associated with CCS. However, there are differences in the underlying assumptions of the LCAs as well as methodological shortcomings that yield heterogeneity of results. Without a better understanding of the technology, it is not possible to give a comprehensive picture. There also remains a wide field of subjects and technologies that have not yet been covered.

Lessons Learned from a Life Cycle Sustainability Assessment of Rare Earth Permanent Magnets

Summary In order to address methodological challenges during life cycle sustainability assessment (LCSA), this article combines the results of a life cycle assessment (LCA), a life cycle costing, and a social LCA using the example of a complex product: a rare earth permanent magnet for use in wind turbines. The article presents different approaches for combining the results of separate assessments with its attendant methodological challenges. Different normalization, aggregation methods, and weighing factors are applied and their impacts on the results are compared. The underlying case study makes an evaluation of these different methodologies more concrete. Results show that the normalization method applied has a greater influence on the overall results than the aggregation method or weighting factors. Additionally, this study shows that indifference thresholds should be applied to avoid overestimation of small impacts. Indifference thresholds ensure that impact categories with nearly the same results for all analyzed options are treated as identical results. The study also indicates the importance of the question of how much compensation between impacts is desirable. Despite the impact of these factors, the chosen case study of an LCSA for permanent magnets with different supply routes for rare earths shows that the ranking of Chinese production is the most problematic irrespective of the approaches applied.

Environmental Aspects of CCS

The use of CO2 capture technologies causes efficiency losses which leads to an additional demand of fuel and related other emissions. Also necessary operating materials and a change in waste composition are consequences of this utilisation. Life Cycle Assessment (LCA) has proved to be a helpful tool to investigate the different environmental consequences associated with the introduction of CCS. For all capture routes environmental effects of conventional capture technologies are analyzed. Additionally, the impacts of a second generation capture technology, ceramic membranes, are investigated. The share of life cycle segments, such as power plant operation, fuel supply or CO2 transport and sequestration, can be identified for the different impact categories. Generally, the intended decrease of CO2 emissions goes along with an increase in most other impact categories regardless of technology or fuel used.