The urgency of the energy transition, combined with geopolitical tensions over critical raw materials, has increased interest in deep-sea mining of polymetallic nodules. However, there are serious concerns about its environmental impacts. Life Cycle Assessment (LCA) is currently used to support claims that metals from deep-sea mining are environmentally more preferable than those from land-based mining. However, LCA addresses only generic environmental impacts, and previous LCAs comparing deep-sea and land-based mining show considerable variation in outcomes. This study critically examined the applicability of LCA for comparing deep-sea and land-based mining by analysing previous LCAs, developing an aligned LCA, and discussing limitations. Previous LCAs consistently reported lower climate change impacts for deep-sea mining, but the magnitude of this benefit varied due to methodological choices, data inputs, and assumptions, especially regarding energy. The aligned LCA found lower impacts for deep-sea mining in almost all 20 evaluated categories, except transformation of natural land, including the seabed. However, the results depended strongly on LCA design choices: under renewable electricity scenarios, land-based mining outperformed deep-sea mining for climate change and energy resources. Trade-offs emerged, such as high water use from hydropower and ionising radiation from nuclear energy. The study highlighted both strengths and limitations of LCA in this context, and emphasized that it should be complemented by location-specific assessments to capture social, economic, biodiversity, and ecosystem impacts. This study did not conclude whether deep-sea mining is environmentally more preferable than land-based mining, but it identified conditions under which it results in lower generic environmental impacts, and highlighted critical considerations, knowledge gaps, and uncertainties to guide policy making and future research.

Most electronic devices depend on Critical Raw Materials (CRMs) to be produced or repaired.
As such, this increasing dependency represents an emerging threat to the resilience of modern
technological systems; without these materials, essential devices such as servers and modems could become inaccessible. Most CRMs lack short-term substitutes and are often sourced from regions with low levels of governance or complex geopolitical relationships with the European Union (EU). In addition to supply risks, the primary production of CRMs is associated with environmental impacts such as resource depletion, acidification, biodiversity and greenhouse gas emissions. These dynamics emphasize the need for innovative solutions that reduce dependency on primary materials, for which a suggested approach is increased circularity.
Therefore, this study addresses the dependency on primary CRMs by exploring strategies to
reduce or slow primary material inflow through circular practices, focusing on the end-of-life (EoL) stage of consumer telecommunication products. This is done through static (bookkeeping) and dynamic Material Flow Analysis (MFA), applied within the Dutch context and in collaboration with telecom provider KPN. KPN currently applies circular measures, such as product reuse and recycling, to some of its distributed devices. However, a comprehensive overview of CRM quantities within product flows, as well as a structured outlook for future CRM circularity, were not yet developed. Consequently, this study addresses this gap by providing insights in applied CRM circularity practices and future strategies, based on one of KPN’s most distributed products. The outcome offers pragmatic insights for KPN to slow primary CRM demand, aligning with the EU Critical Raw Materials Act and the company’s own sustainability objectives to achieve net-zero emissions in the value chain by 2040. Of the circular practices applied to an internet modem as use case, reuse shows the highest potential: compared to the total primary production and transport, the total emission reduction through reuse could amount to roughly 0.814% of emissions in the Dutch communications sector over the y to y+14 period. From a materials perspective, this research identified fifteen CRMs in the product under study. For these materials, reuse and recycling could prevent the need for 624 kg of CRMs on the printed circuit board. Including aluminium from the heatsink, material savings increase to a total of 241 tonnes, which equates to a Global Warming Potential (GWP) impact score prevention of up to 83.5% over the device’s total material production. Herein, mainly recycling has some limitations as KPN only applies open-loop recycling to a limited set of CRMs.
Furthermore, the study evaluates the potential of future circular strategies, such as improved
waste management, product lifetime extension, and increased CRM recycling. These scenarios
suggest that additional material savings could reach up to 10.7 tonnes, with an additional GWP
impact score prevention of around 3.89%. Increasing total GWP prevention from 83.5% to 87.4%. However, as this study uses a single product as use case, scaling this study’s approach across a broader range of telecommunication or other similar products is recommended to confirm whether substantial company- or sector-wide impact can be identified. In addition, this study recommends to also explore further possibilities to increase circularity; such as advancing on the R-ladder through refusing, rethinking and reducing the use of CRMs and critically assess how EU recycling targets could still be met within the limited remaining time.
Finally, this study contributes to the scientific debate by exploring the underexamined area
of CRM flows in telecom equipment through circular strategies. By taking an industrial ecology
(IE) perspective, it applies a systems approach to position KPN’s supply chain within its wider
environmental context, offering both practical implications and theoretical insights.

The steel industry is undergoing a transition that is driven by two key factors: the decarbonisation of the production process and the promotion of circularity. This transition involves a shift from coal to renewable energy sources for decarbonisation purposes and from iron ore to scrap-based steelmaking, thereby facilitating the transition to a circular economy. In this context, the availability and quality of steel scrap become critical factors in facilitating the transition to scrap-based steelmaking. This master thesis employed a dynamic material flow analysis (dMFA) to assess steel and scrap metabolism in Europe, focusing on trade impacts, scrap sorting, and steel production methods. Three scenarios, no trade deficit(1), business-as-usual trade (2), and high trade deficit (3) were analysed, alongside improved scrap sorting strategies. Key findings indicate that a circular steel industry requires a shift to electric arc furnace (EAF) steelmaking with minimal trade deficits to ensure high-quality scrap availability. Achieving an 80% intermediate level sorting rate for end-of-life steel scrap by 2050 is critical for closing the loop on steel production. Additionally, optimizing scrap distribution within Europe is essential to prevent downcycling and reduce tramp element accumulation. The study underscores the need for Europe to support global sustainable steel production as part of climate responsibility. Future research should refine key assumptions, conduct sensitivity analyses, and enhance scrap categorization and sorting data.
The model, code, and data are available in the supplementary materials.

Tailings are a waste product of primary metal production. Although these metals contribute to the development of modern technology and renewable energy systems, tailings pose significant environmental, economic, and human health risks. Stored behind a dam in tailings storage facilities (TSFs) these waste materials are meant to be isolated from the surrounding environment. However, in the last 120 years at least 350 tailings dam have collapsed, resulting in over 2500 casualties, tens of billions of dollars in financial losses, and severe damage to waterways and the environment. There is a worrying trend of failures becoming more severe and increasing in intensity, and because metal demand is increasing and ore grades are declining, this could potentially become more problematic in the near future.

This study concisely describes the production and disposal of tailings and gives background information on tailings dam failures. Furthermore, it provides a basis for understanding the variations between TSFs across resources categories. Finally, it contributes to the quantification of future copper tailings generation in light of the renewable energy transition. It does so by giving an overview of scientific literature on TSFs, by providing global inventory of TSFs categorized by resource type, and by forecasting the copper tailings production until 2040. Two research question have been answered:

RQ1: To which resources are tailings storage facilities linked?
RQ2: How will the renewable energy transition affect copper tailings production until 2040?

RQ1 presents a comprehensive overview of the resources associated with tailings storage facilities by identifying the primary resources linked to each TSFs. This was done by combining a database on existing TSFs worldwide (GRIDA) with a database that contains mining and mineral processing hubs (USGS MRDS). TSFs have been linked with USGS MRDS hubs by using location data using the geographic information system QGIS and by matching TSFs and mine based on their names. Resource data of TSFs that could not be linked with USGS MRDS data has been manually added by systematically analysis of company websites that own the TSFs, supplemented with scientific literature regarding mining locations, thereby forming the GRIDA+ database.

RQ2 forecasts how the ongoing renewable energy transition will impact copper tailings production up to 2040. Because renewable energy systems use more copper than their fossil equivalents, the energy transition will cause an increase in copper demand. Three IEA energy scenarios (STEPS, SDS, and NZE) have been used as basis for this copper demand. By taking into account the copper recycling rates, ore grades, and smelting efficiency based on scientific literature, this study quantifies the anticipated increase in annual copper tailings production in the period 2020-2040.

This study has identified 27 resource categories linked to TSFs in GRIDA+. The 10 most notable categories are gold, copper, aluminium, lead-zinc, coal, iron, PGE-nickel-chromium, silver, diamond, and manganese. Combined they account for over 90% of TSFs worldwide and 93% of the global tailings volume. Among these categories, the top 3 commodities (copper, gold, and iron) contribute to approximately 74% of the overall tailings volume. Copper accounts for approximately 41% of the total volume reported in the GRIDA+ database, and copper TSFs are among the largest in the world in terms of pond capacity and dam height. The presence of upstream dams in copper TSFs is a cause for concern, as historical data indicates that such dams have a higher likelihood of failure. Additionally, nearly one-third of copper TSFs are inactive, rendering them more susceptible to failure compared to officially closed dams. However, copper TSFs demonstrate relatively favourable performance in terms of stability concerns, the availability of engineering records, and resilience against extreme weather events compared to other resource categories.

The forecasts of the 2040 annual global production indicates that of copper tailings production will grow significantly compared to 2020. The tailings-to-metal ratio of copper will increase from 193:1 to 237:1 and the annual copper demand will increase with 31% to 67%. This will increase the annual copper tailings production with 41% in the STEPS scenario, 47% in the SDS scenario, and 79% in the NZE scenario compared to 2020. In this last scenario the annual tailings production is estimated at 3,740,000,000 m3, which in volume is equivalent to 66% of the annual global crude oil production. Copper tailings is primarily driven by the growing demand for copper and to a lesser extent by the diminishing copper ore quality. Advancements in recycling rates and the possible deterioration of copper smelting efficiency could respectively have a substantial dampening or additional effect on future copper tailings growth.

Because of the expected surge in copper tailings production enhancing tailings storage facility management and improving copper recycling are two important challenges for the future. Converging factors such as increasing mineral demands, diminishing ore grades, advancements in extractive and processing technologies may cause the mining industry to start new mining operations and rapidly upscale existing projects. This puts additional pressure on existing and planned TSFs, leading to additional risks of tailings dam failures. These developments make urgent action necessary in order to prevent future TSF catastrophes and to assure a save, sustainable, and stable supply of copper and other minerals in the future.

Policymakers should adopt measures to limit copper demand and improve copper recycling rates, aim at including the effects of tailings dam failures in Life Cycle Assessments (LCAs) thereby emphasizing the benefits of recycled copper, and enforce a comprehensive industry standard for tailings management.

The capture of carbon dioxide before or after it is emitted has been regarded as a crucial mitigation pathway to prevent the rapidly increasing accumulation of CO2 in the atmosphere. The valorisation of the captured CO2 into value added products such as methanol provides an additional economic incentive to continue developing these technologies. The company Zero Emission Fuels B.V. (ZEF) is currently developing a mass-producible miniature methanol plant that houses a Direct Air Capture and CO2-compression unit, an Alkaline Electrolysis Cell, a Methanol Reactor, and a Distillation unit. Potential benefits of this approach are in the economies of scale of production, and autonomous operation in areas of high solar irradiation due to direct integration with PV systems.
To validate the microplant-concept from an environmental perspective, a research project was executed with the goal to establish the environmental profile of the microplant, to identify hotspots for impact mitigation, and to assess the position of the microplant’s environmental profile in relation to results of comparable technologies reported in literature. To do so, multiple technological development pathways were considered that project the current microplant’s performance into a range of future states.

The impact assessment of the future PV-powered air-to-methanol plant, suggests that it is likely that methanol produced using this approach will exhibit a low (negative cradle-to-gate) climate change impact along its production chain, especially compared to conventional methanol produced via the steam reforming of natural gas. Environmental trade-offs are incurred by the additional material demand compared to conventional methanol, instilled both by the electricity generation from PV panels and the added material demand of the thousands of micro-plants that need to be produced for sufficient methanol production volume.
Using polyamine sorbents for the process of capturing CO2 from the atmosphere inevitably leads to sorbent degradation which in turn can cause emissions of various substances. Using rough estimations via a worst/best case approach, it was analysed that emissions from the capture unit are relevant in three impact categories.
Overall, the additional material demand and sorbent-related emissions introduce significant trade-offs in between 5-8 impact categories, depending on the followed technological scenarios. Additional technological improvement may reduce the trade-off effect, leading to a reduction of trade-off categories to a number of four.

The analysis concluded that it is likely that there are benefits to using the microplant-approach to methanol production, though additional research is critical to iron out the large uncertainties that are paired with future-oriented life cycle assessment.

Wind turbine blades are composed of complex composite material structures that are difficult to recycle at the end of their operational lifetime. As such, they are oftentimes landfilled or incinerated. Following the Circular Economy principles, there are a multitude of strategies that may be applied to these structures; these range from more to less desirable, where landfill and incineration are categorised as least desirable. In the ambition to reduce greenhouse gas emissions and reach agreed upon climate goals, the implementation of wind power plays a central role in the Netherlands, and hence the number of end-of-life wind turbine blades will significantly increase in the coming decades. In an attempt to better manage this issue, the creation of a central circular hub as treatment facility for these end-of-life blades has been suggested. Hence, a framework is developed to compare ports with regard to their suitability for the development of a circular wind hub. The framework is based on six categories: port willingness, available space, existing companies and infrastructure, accessibility, focus on circular strategies, and centrality with respect to return volumes. Subsequently, different ports in the Netherlands are compared for the establishment of a circular wind hub. The Port of Den Helder and Port of Amsterdam come forward as most suitable locations, with a strong willingness and being most centrally located. However, it is also highlighted that the hub need not be limited to one single location - in fact, it could be valuable to collaborate and create synergies across ports. Additionally, interregional collaboration with neighbouring countries of the Netherlands – Germany, Denmark, the United Kingdom, France, and Belgium – will help to improve the economic viability of such a hub. This research therefore performs a geographical explicit quantification of the availability of end-of-life wind turbine blades in this region between 2020-2050, and places the results in the context of three circular strategies based on reusing, repurposing and recycling the blades, respectively. This is done through the use of a dynamic Material Flow Analysis and the use of a Geographic Information System. The results indicate a clear increase in end-of-life wind turbine blades in the defined region until 2050, reaching a cumulative amount of 690 kilotonnes by 2050. Application of the circular strategies strongly influences the amount of material for which it is economically viable to be treated in the hub. In all cases, this is significantly lower than the total amount of material in the region. Among the three strategies, reusing the blades results in the highest amount of material treated, energy saved and economic benefits realised. However, the potential market size seems largest for recycling the blades and smallest for reusing them; hence regulation for this disparity is called for. Furthermore, a push is needed for the viable volumes under application of the circular strategies to better approach the total volume in the region. To accomplish this, it is imperative that the economic value of the secondary material be increased, as well as the documentation of wind turbine blades and transparency in the value chain be improved. All in all, this research expresses the urgency, feasibility and potential value of the development of a circular wind hub for end-of-life wind turbine blades in the Netherlands.