This study builds a bridge between the advancements from prospective life cycle assessments (pLCAs) and dynamic life cycle assessments (dLCAs) to improve the evaluation of circular economy (CE) strategies for long-lived products such as energy technologies. Based on a literature review of recent developments from pLCA and dLCA, an extended LCA methodology is proposed that provides guidance in the consideration and integration of technological and market dynamics across all major LCA steps of a dLCA, whose flows and impacts extend over a long period of time. This ensures a more accurate assessment of the impacts on global warming over time by explicitly incorporating temporal differentiation into goals and scopes, life cycle inventories, and interpretations. The methodology was applied to compare two CE measures for wind turbines: full repowering, including material recycling, and partial repowering. The analysis revealed that full repowering is the environmentally preferable option from the perspective of global warming potential, as the higher electricity output offsets the emissions associated with decommissioning and new construction. The findings were robust under various assumptions on future technological advancements, the underlying decarbonization scenario aligned with the Paris Agreement, and the application of discounting of future emissions. Ultimately, this work provides a practical yet adaptable approach for integrating future-oriented LCA methods into decision-making for more sustainable infrastructure and machinery.

Energy conversion and infrastructure facilities consist of large amounts of metal and have lifetimes of several decades. When recycling metals, the methods of allocation play a decisive role in evaluating how primary and secondary materials, as well as the products that are produced with them, are to be evaluated ecologically. So-called credits for recycling are the subject of a particularly controversial discussion. This article shows that the current practice of giving credits for long-lasting products leads to a significant distortion of the actual emissions. Using the examples of steel, aluminum, and copper, prospective LCA data is used to show how the carbon footprint actually behaves. When credits are applied, the time dependency of emissions must be taken into account; otherwise, burden shifting into the future occurs, which can hardly be considered sustainable. The increase compared to the conventional time-independent practice lies, depending on the metal, at 70 to 300%. It is recommended that the cutoff approach be used conservatively when allocating recycling cascades in order to optimize environmental impact and avoid greenwashing.

At the COP27 France called for a ban on deep sea mining. The topic has gained momentum over the last years as some stakeholders promoted the mining of manganese nodules as a less CO2-emitting way to meet the rising demands of nickel, copper, cobalt, and manganese. In this study, we modelled the climate impacts caused by metal production from manganese nodules versus land-based mining. The climate impact of producing Ni-Cu-Co-FeMn from manganese nodules (~2.0 kg CO2-eq / kg dry nodules) compared to actual land-based projects is about 27 % lower. Comparing it to literature values from industry associations and the ecoinvent database, the climate impacts from manganese nodules are about 16 % lower, or 27 % higher respectively. Hence, climate change should not be the central argument for/against manganese nodule mining. The discussion should instead explicitly include further environmental impacts e.g., biodiversity or plumes as well as economic considerations.