Uranium, a cornerstone for nuclear energy, facilitates a clean and efficient energy conversion. In the era of global clean energy initiatives, uranium resources have emerged as a vital component for achieving sustainability and clean power. To fulfill the escalating demand for clean energy, continual advancements in uranium mining technologies are imperative. Currently, established uranium mining methods encompass open-pit mining, underground mining, and in situ leaching (ISL). Notably, in situ leaching stands out due to its environmental friendliness, efficient extraction, and cost-effectiveness. Moreover, it unlocks the potential of extracting uranium from previously challenging low-grade sandstone-hosted deposits, presenting novel opportunities for uranium mining. This comprehensive review systematically classifies and analyzes various in situ leaching techniques, exploring their core principles, suitability, technological advancements, and practical implementations. Building on this foundation, it identifies the challenges faced by in situ leaching and proposes future improvement strategies. This study offers valuable insights into the sustainable advancement of in situ leaching technologies in uranium mining, propelling scientific research and practical applications in the field.

Excessive emissions of greenhouse gases, primarily carbon dioxide (CO₂), have garnered worldwide attention due to their significant environmental impacts. Carbon capture, utilization, and storage (CCUS) techniques have emerged as effective solutions to address CO₂ emissions. Recently, direct air capture (DAC) and bioenergy with carbon capture and storage (BECCS) have been advanced within the CCUS framework as negative emission technologies. BECCS, which involves cultivating biomass for energy production, then capturing and storing the resultant CO₂ emissions, offers cost advantages over DAC. Algae-based CCUS is integral to the BECCS framework, leveraging algae’s biological processes to capture and sequester CO₂ while simultaneously contributing to energy production and potentially achieving net negative carbon emissions. Algae’s high photosynthetic efficiency, rapid growth rates, and ability to grow in non-arable environments provide significant advantages over other BECCS methods. This comprehensive review explores recent innovations in algae-based CCUS technologies, focusing on the mechanisms of carbon capture, utilization, and storage through algae. It highlights advancements in algae cultivation for efficient carbon capture, algae-based biofuel production, and algae-based dual carbon storage materials, as well as key challenges that need to be addressed for further optimization. This review provides valuable insights into the potential of algae-based CCUS as a key component of global carbon reduction strategies.

Carbon dioxide (CO₂), as the primary greenhouse gas, has significant impacts on global climate change, leading to severe and irreversible adverse consequences for ecosystems and human environments. To address the issue of excessive CO₂ emissions, efforts in recent years have yielded significant progress in the development of clean energy sources and the promotion of carbon capture, utilization, and storage (CCUS) technologies. Conventional CO₂ capture techniques are limited in addressing global atmospheric CO₂ excess effectively, as they target only high-concentration CO₂ emissions and require implementation at specific emission points. Direct air capture (DAC) technology has emerged as a promising solution due to its flexibility in deployment, avoidance of land competition, and ability to capture legacy CO₂ emissions. Additionally, DAC offers opportunities for producing synthetic clean fuels, thereby reducing reliance on traditional fossil fuels and aiding in reducing greenhouse gas emissions. This study provides a comprehensive review of DAC technology, encompassing its principles, technological advancements, real-world applications, challenges, and future research directions. By offering insights into the current state and potential of DAC technology, this study aims to guide global efforts in scaling up DAC deployment, ultimately contributing to achieving global carbon neutrality or even negative emissions.

With the intensifying global climate crisis and the urgent demand for carbon neutrality, carbon dioxide (CO₂) capture technologies have received growing attention as effective strategies for mitigating greenhouse gas emissions. Carbon-based porous materials are widely regarded as promising CO₂ adsorbents due to their tunable porosity, high surface area, and excellent chemical and thermal stability. Among them, biomass-derived porous carbon materials have received growing attention as sustainable, low-cost alternatives to fossil-based adsorbents. This review provides a comprehensive overview of recent advances in biomass-derived porous carbon materials for CO₂ capture, emphasizing the fundamental adsorption mechanisms, including physisorption, chemisorption, and their synergistic effects. Key synthesis pathways, such as pyrolysis and hydrothermal carbonization, are discussed in relation to the development of biomass-derived porous carbon materials. Furthermore, performance-enhancing strategies, such as activation treatments, heteroatom doping, and templating methods, are critically evaluated for their ability to tailor surface properties and improve CO₂ uptake capacity. Recent progress in typical biomass-derived porous carbon materials, including active carbon, hierarchical porous carbon, and other innovative carbon materials, is also highlighted. In addition to summarizing recent advances in porous carbon synthesis, this review introduces a unified techno-economic framework that integrates cost, sustainability, and performance-driven benefits. Overall, this review aims to provide systematic insights into the performance of biomass-derived porous carbon materials and to guide the rational design of efficient, sustainable adsorbents for real-world carbon capture applications.

Uranium is a resource with exceptionally high energy density, releasing substantially more energy per unit mass than conventional fossil fuels. In uranium mining, in situ leaching offers significant advantages over open-pit and underground mining, including reduced environmental impact, lower operational costs, enhanced safety, and improved controllability. Within the in situ leaching framework, acid leaching faces limitations in high-carbonate ore bodies, while alkaline leaching is unsuitable for deposits rich in pyrite and other sulfide minerals due to side reactions and precipitate formation that hinder leaching efficiency. In contrast, CO₂-O₂ leaching, as a neutral leaching approach, exhibits broader applicability across diverse ore types and geological settings. Incorporating CO₂ into the leaching process also enables carbon utilization, offering a potential pathway to cleaner uranium extraction aligned with carbon reduction and sustainable energy goals. This review systematically examines the geochemical principles, as well as hydrological and transport phenomena governing CO₂-O₂ in situ leaching. Recent technological advances are summarized, including progress in reaction kinetics and leaching efficiency, leaching solution design and control, and reservoir modification. Furthermore, the techno-economic implications of CO₂-O₂ in situ leaching are critically assessed, with particular emphasis on operational cost structures and the evolution of techno-economic analysis methodologies. On this basis, key challenges and future directions are identified. This work aims to support the future large-scale and economically efficient deployment of CO₂-O₂ in situ leaching for uranium resource development.

Sandstone-hosted uranium deposits represent one of the world’s most important uranium resources and are strategically significant for nuclear energy development, energy transition, and carbon emission reduction. Compared with conventional open-pit or underground mining, in situ leaching has become the dominant approach for sandstone-hosted uranium deposits due to its minimal surface disturbance, higher resource utilization efficiency, and reduced environmental footprint. However, most sandstone-hosted uranium deposits exhibit pronounced reservoir heterogeneity, including permeability contrasts, uneven flow pathways, complex uranium occurrence, and non-uniform advancement of reaction fronts. These factors collectively restrict leaching solution transport, limit uranium mobilization, and reduce recovery efficiency and sustainability of in situ leaching operations. Therefore, achieving efficient, environmentally friendly, and sustainable development of complex heterogeneous sandstone uranium deposits has become a key challenge in in situ leaching research and engineering practice. This review summarizes recent advances in recovery enhancement technologies for in situ leaching of sandstone-hosted uranium deposits over the past decade. Based on the geological and hydrogeochemical characteristics of these deposits, the mechanisms of in situ leaching are first outlined, followed by technological developments in four areas: flow field regulation, reservoir permeability enhancement, geochemical regulation, and reactive-transport coupling enhancement. Current challenges and future research directions are also discussed. This review provides a systematic framework for improving uranium recovery while advancing efficient, environmentally responsible, and sustainable in situ leaching development.