Life cycle-based analysis is a key to understand these biofuels’ climate benefits. This manuscript provides a state-of-the-art review of current biofuel production, primarily through algae-based routes. Standalone biofuel production has an unfavorable environmental and energy footprint. Therefore, industrial symbiosis is required to reduce the environmental impacts of biofuel. The availability of waste heat, CO₂, renewable energy, and colocation of other industries, especially renewable energy and dairy firms, have been demonstrated beneficial for producing biofuel through the algal route. Dynamic life cycle assessment (DLCA) issues were discussed in detail. DLCA is one of the highlighted areas of the Life Cycle Assessment (LCA) paradigm that can improve the applicability of climate change indicators used in the LCA. Various climate change indicators, global warming potential (GWP), global temperature change (GTP), and climate tipping point (CTP) were discussed in detail. Special emphasis was given to waste-based bioenergy production and its LCA as this route provided the lowest GHG emissions compared to the other bioenergy production pathways (e.g., from energy crops, using lignocellulosic biomass, etc.). The use of LCA results and modification of life cycle inventory (e.g., modification in the form of the regional energy mix, dynamic Life Cycle Inventory (LCI), etc.) was another highlight of this study. Such modifications need to be incorporated if one wants to improve the applicability of LCA results for net zero target analysis.

Green lean six sigma (GLSS) has emerged as an integrated methodology that combines the waste-reduction focus of Lean, the quality enhancement of Six Sigma, and the environmental responsibility of Green practices. Despite growing interest, the field remains underdeveloped and needs more targeted investigations. This study systematically reviews existing literature, identifies trends, categorizes contributions, realizes challenges, and proposes future research directions to contribute to GLSS enhancement in both theory and practice. Using a structured keyword search strategy (“Green Lean Six Sigma” and “sustainable Six Sigma”), peer-reviewed articles from 2014 to 2024 were collected from EBSCOhost, Google Scholar, and Lens.org. A total of 121 articles were selected based on the inclusion of both Lean and Six Sigma methodologies within a sustainability context. Thematic analysis was used to classify the studies into major categories including frameworks, sectoral applications, drivers, effect analysis, enablers and barriers. Descriptive analysis was also carried out to illustrate the studies’ trends and distribution. Additionally, bibliometric mapping was conducted to visualize research concentration. The findings show that GLSS is promising in improving operational and environmental performance, especially when supported by digital technologies and strategic alignment. However, most studies are conceptual, manufacturing-focused, or lack holistic methodologies, or standardized sustainability metrics. Finally, the review proposes targeted research pathways in empirical testing, sector-specific adaptation, developing standard measurement methods, and integration with Industry 4.0 and Circular Economy. These insights provide a robust knowledge base for scholars, industry leaders, and policymakers aiming to improve GLSS implementation in support of global sustainability goals. Graphic abstract

The concept of Environmental Justice (EJ) has evolved in United Sates for more than 30 years. Since then most empirical studies have shown that low-income and minority neighborhoods are disproportionately exposed to environmental hazards. Across the world, communities are struggling to protect their land, air, water, forests, and their livelihoods from damaging projects and activities with heavy environmental and social impacts. A Number of tools already exist to identify and map those areas with potential environmental justice concerns. This paper presents a comparison of the three major EJ tools; EJSCREEN (version 2016), CalEnviroScreen 2.0, EJ Atlas and their methodologies. There are some common parameters across these tools in presenting Environmental Justice and in identifying environmentally burdened communities, socially burdened communities, or both. Environmental burdens can include any environmental pollutant, hazard or disadvantage that compromises the health of a community. The tools are expected to help in understanding and studying the distribution of environmental benefits and burdens, decision making for disadvantaged communities in certain areas and in setting up environmental policies and planning.