Toward Carbon Neutrality: Improving Resource Efficiency

Energy efficient lights, such as fluorescent lamps (FLs) and light-emitting diode (LED) lamps, can greatly help energy saving, which is critical for achieving carbon neutrality in the building sector. Yttrium, europium, and terbium are three essential rare earth elements (REEs) for energy efficient lighting. However, due to the ongoing lighting technology transition from FLs to LED lamps, the demands for yttrium, europium, and terbium have decreased significantly. It resulted in oversupplies of these three REEs in the lighting sector, indicating an economically and environmentally unsustainable supply chain. This study aims to estimate the supply and demand dynamics of yttrium, europium, and terbium in China from 2021 to 2060 under China's carbon neutrality target by applying a dynamic-material-flow-analysis framework. Key flows and stocks along their life cycles are examined. Results show that the annual demands for yttrium, europium, and terbium in China's lighting sector will decrease by 87%–100% from 2021 to 2060 under two demand scenarios. Driven by the demands for other co-produced critical REEs, the overall growing REEs supply will result in high surplus risks of yttrium and europium. Meanwhile, terbium deficit risk deserves more attentions due to its demand growth in other fields. Such surpluses of these three REEs in 2060 under six combined demand and supply scenarios are estimated to reach between 71 727 tonnes and 274 869 tonnes for yttrium, 530 tonnes and 1712 tonnes for europium, and −1360 tonnes (i.e. deficit) and 540 tonnes for terbium. Recycling activities of major co-produced REEs, such as neodymium, and the export expansion of surplus products can effectively mitigate such surplus risks. Finally, policy recommendations are proposed to improve the overall REEs efficiency by addressing the supply–demand imbalance and mitigating corresponding environmental impacts.

Recycling steel scraps by the use of electric arc furnace is one of the most promising approaches for the steel industry to achieve net-zero emissions. Due to the uneven distribution of global steel scraps, many countries are actively involving in the global steel scraps trade. Steel scraps contain a range of critical elements, which may be transferred across borders through international trade of steel scraps. However, existing studies have paid little attention to the global flows of steel scraps and its embodied alloy elements (AEs). This study maps the journey of global steel scraps and the embodied AEs for the period of 2000–2021 for the first time by employing trade-linked material flow analysis and social network analysis. The results indicate that the global steel scraps trade had increased during the study period, with a few core countries (such as USA, Germany, and Turkey) leading the global steel scraps network. Also, critical metals had been transferred across borders in the form of AEs through the trade of steel scraps, especially from global north countries to global south countries. The largest AE flows include Chromium (Cr), nickel (Ni), manganese (Mn) and molybdenum (Mo) flows. Other AE flows, such as cobalt (Co), vanadium (V), and niobium (Nb) flows, were less, but with high values or being regarded scarce. From a global perspective, steel scraps trade and recycling can contribute to the decarbonization efforts of the global steel industry and address resource shortages in some countries. Therefore, it is urgent to promote the overall resource efficiency of steel scraps and the embodied AEs by various efforts.

Biomass waste-to-energy (WtE) offers a critical solution to carbon neutrality through improving the resource recycling and recovery. This study comprehensively assessed how WtE can be implemented in generating electricity for Cameroon with an estimation to the energy potential of anaerobic digestion of three organic waste streams including municipal solid waste, wastewater sludge, and livestock manure. We assessed the energy potential in terms of the theoretical, technical, and economic potentials. The findings highlighted a theoretical energy potential of 936.37 TWh y^r−1 in Cameroon. If only applied to a fraction of organic wastes, the technical potential could reach 48.64 TWh y^r−1. Furthermore, considering the economic costs of technology installation, 17.06 TWh y^r−1 could be generated, and this economic generation potential could supply to 38.9% of the country's current electricity demand. This study implies that WtE would significantly reduce fossil fuels consumption and greenhouse gases emissions from poorly disposed wastes, to enable decarbonization transition and improve human health in African countries.

Different from existing studies that only analyze the emission reduction efficiency or mitigation of a single pollutant by the air pollutant control policy, this study focuses on synergies and efficiency of reducing CO₂ and air pollutants. We select the panel data from 30 provinces and cities in China from 2013 to 2020, and apply the difference-in-differences model to assess China's three-year action plan to fight air pollution (referred to as the three-year action plan). To distinguish the method of measuring single pollution emission efficiency, we calculate synergistic efficiency of reducing CO₂ and air pollutants emissions through the super-efficiency slack-based measure model which considering various pollutants as undesirable outputs. Furthermore, this study conducted regional heterogeneity analysis of resource endowments by incorporating interactive items of regional dummy variables. The results of study demonstrate the three-year action plan achieve synergies and efficiency of reducing CO₂ and air pollutants. And the policy effects are also more pronounced in non-resource-based regions. Furthermore, the three-year action plan enhances management level and the potential for synergistic mitigation, as well as the beneficial effects on resource allocation efficiency and capacity improvement in key regions.

A transformation towards a bioeconomy is needed to reduce the environmental impacts and resource requirements of different industries. However, considering the finiteness of land and biomass, such a transition requires strategizing resource and land allocation towards activities that yield maximum environmental benefit. This paper aims to develop a resource-based comparative indicator between economic sectors to enable optimal use of biobased resources. A new methodology is proposed to analyze the climate effectiveness of using straw in the agricultural, energy and construction sectors. For this purpose, avoided and delayed emissions are analyzed for different use cases of straw and then compared. Considering only avoided emissions, the use of straw as a feedstock for bioelectricity has the highest climate effectiveness (930 kg CO₂ eq./t_straw). Considering only temporal carbon storage, straw-based insulation in buildings has the highest climate effectiveness (881 kg CO₂ eq./t_straw). Combining avoided and delayed emissions, the use of straw-based insulation has the highest climate effectiveness (1344 kg CO₂ eq./t_straw). Today EU-Policies incentives the use of straw in the agricultural sector and the energy sector, neglecting the benefit from its use in the construction sector. The results can support policymakers' trans-sectoral incentives, where agriculture by-products are diverted towards the use of biomass that most boost economic activities and trigger maximum environmental benefit, given the local circumstances.

This article addresses ship recycling. Often criticized for dire health and safety conditions at breaking destinations in the Global South, our article considers ship recycling as a potential future source for secondary steel in green transformations. It represents an analysis of forthcoming changes in the regulatory framework, an initial assessment of steel stocks based on publicly available data, and a local case study. Here, the article assesses the capability of Bremen, a city in Northern Germany, to gain a relevant future market share. Our results indicate (a) the regulatory framework is dynamic due to the entry into force of the Hong Kong Convention in 2025 und the current revision of the EU Ship Recycling Regulation; (b) the future market is significant, roughly equivalent to the entire current US car fleet in terms of steel stocks; (c) the ability to act locally depends on a variety of critical factors, including political will, entrepreneurial capital, and space requirements. The article concludes with an outlook on the importance of such a development for the transition towards 'net zero steel' and provides a perspective on future research needs.

Mitigation of climate change requires comprehensive policy arrangements. This article applies a systematic analysis framework comprising 'vertical policy hierarchy—horizontal policy path—policy instruments' with Germany, France, and the Netherlands as study cases, and first-hand policy and data from government websites collected, clustered, and matched. The study conducts a comparative analysis of the three countries' systems, pathways, instruments, and their effectiveness in climate change mitigation. The findings indicate that, firstly, all three countries have relatively well-developed policy systems (laws, regulations, strategies, plans, and policy instruments) based on the six vertical policy hierarchy defined by government governance structure. Secondly, the three countries exhibit commonalities and disparities in seven sectors: energy, transport, buildings, industry, agriculture, forest, and waste. The commonalities stem from EU laws and directives, while disparities arise from resource endowments and emission structures. Thirdly, regarding policy instruments, the commonalities among the three countries are reflected in the dominance of Financial/Fiscal Mechanisms as the primary approach, the leadership position of Governance Mechanisms, the comprehensive coverage of Regulatory Reform, and the massive expenditure in the Direct investment. Individually, (1) the German Regulatory Reform primarily addresses energy resource transformation; France focuses on controlling the transport sector emissions; while the Netherlands commits to renewable energy generation. (2) Germany leads in terms of Commercialization Mechanisms. (3) Financial/Fiscal Mechanisms encompass all sectors, while Germany examplifies the transportation sector digitization, France's provision of ecological housing loans, and the Netherlands' support for sustainable agriculture. (4) France distinguishes itself with a forward-thinking approach towards Governance Mechanism including climate financial risks, ESG (Environmental, Social, and Governance) standards. Fourthly, the significant policy instruments analysis demonstrates that the climate governance of three countries incorporates not only direct or indirect efforts in emission reduction, but also considerations of institutional requirements, fairness, economic effectiveness, synergies, and transformative potential in policy considerations.