The aviation sector is recognized as one of the most challenging industries to decarbonize, prompting increasing global interest in Sustainable Aviation Fuel (SAF) derived from low-carbon and waste-based feedstocks. In Indonesia, Palm Oil Mill Effluent (POME) represents a significant industrial by-product with potential strategic relevance for SAF development within a circular economy framework. This study aims to systematically synthesize and evaluate existing scholarly evidence on POME-based SAF development in Indonesia, focusing on technological pathways, deployment barriers, and strategic imperatives for scaling in support of global aviation decarbonization. This research employs a Systematic Literature Review (SLR) approach. Data were collected exclusively from peer-reviewed journal articles indexed in the Scopus database. An initial search using the keywords “sustainable aviation fuel” AND “biofuel” yielded 671 articles, which were refined through targeted Boolean queries, publication year filtering (2019–2025), and Open Access/Open Archive screening, resulting in 25 eligible studies. Data analysis was conducted using thematic synthesis to integrate technological, environmental, economic, infrastructural, and policy dimensions. The results indicate that anaerobic digestion-based pathways combined with Fischer–Tropsch and Alcohol-to-Jet conversion dominate POME-based SAF research, with reported lifecycle greenhouse gas reductions of 60–85%. While feedstock availability is abundant, scalability is constrained by capital intensity, infrastructural dispersion, and limited SAF-specific policy support. In conclusion, POME-based SAF development in Indonesia is technically and environmentally viable but requires coordinated policy frameworks and infrastructure integration. Future research should prioritize integrated techno-economic and lifecycle assessments to strengthen evidence-based policy formulation.

Renewable Energy Communities (RECs) are recognized as effective collective models to accelerate decarbonization through shared renewable generation, consumption, and local flexibility provision. However, their large-scale deployment remains constrained by the temporal mismatch between variable renewable generation and strongly time-dependent demand, particularly in buildings where heating and cooling dominate final energy use. This state-of-the-art review provides an integrated and comparative assessment of Thermal Energy Storage (TES) and Battery Energy Storage Systems (BESS) within RECs, with explicit focus on power-to-heat (PtH) pathways and phase change material (PCM)-based cooling storage. Based on a structured analysis of the peer-reviewed literature published between 2015 and 2025, the review shows that TES represents a cost-effective and durable complement to electrochemical storage in heating- and cooling-dominated communities. Reported results indicate that TES integration can reduce peak electrical demand by 20–35%, increase local renewable self-consumption by 15–40%, and significantly lower required battery capacity in hybrid configurations. While BESS remains indispensable for short-term electrical balancing and fast-response grid services, TES offers lower costs per kWh stored, longer operational lifetimes (often exceeding 25–40 years), and lower lifecycle greenhouse gas emissions, typically 70–85% lower than those of BESS when thermal energy is used directly. Among TES technologies, PCM-based systems demonstrate particular effectiveness in cooling-dominated RECs, enabling peak cooling power reductions of up to 30% through diurnal load shifting. Across climatic contexts, the literature converges on hybrid TES–BESS architectures as the most robust storage solution, with reported reductions in grid imports and renewable curtailment of up to 35–40%. In addition, TES uniquely enables seasonal energy shifting, for which no cost-competitive electrochemical alternative currently exists. Despite these advantages, the review identifies persistent gaps related to the limited availability of long-term operational data and the need for empirical validation of hybrid control strategies. Future research should prioritize multi-year field demonstrations, advanced data-driven energy management, and policy frameworks that explicitly recognize thermal flexibility and sector coupling within Renewable Energy Communities.

Explaining global variation in life-cycle greenhouse gas (GHG) emissions from soybeans and soybean meal: a systematic review

Advancing Ethanol-to-Jet cost Effectiveness via direct conversion to n-Butene-Rich olefins and Co-Product Valorization.

Cost-effective decarbonization of urban wastewater sector in eastern Chinese cities toward 2035: Integration of low-carbon treatment and energy reduction technologies.

This review provides a comprehensive summary of recent advancements in biodiesel development, integrating bibliometric, techno-economic, and environmental perspectives. Biodiesel has emerged as a sustainable alternative to fossil fuels, and the growing international energy demand has made its production increasingly attractive. Feedstock selection remains a critical factor, encompassing first-generation edible oils, second-generation non-edible oils, third-generation algal biomass, and waste-derived sources. The analysis highlights issues related to land-use change, food-versus-fuel competition, and carbon debt. Technological progress has been achieved through transesterification, supercritical methods, and ultrasound- and microwave-assisted processes, all of which have improved conversion efficiency. Innovations have also introduced furnace-type, homogeneous, heterogeneous, and enzyme-based catalysts. However, these systems present challenges concerning catalyst reusability, soap formation, glycerol recovery, and NOx emissions. Life cycle assessments and greenhouse gas (GHG) modeling reveal key ecological trade-offs, while economic evaluations emphasize the need for more realistic estimates of commercial scalability. Operational limitations such as oxidative instability, low-temperature performance, and reduced flow yields continue to hinder standardization and large-scale deployment. Future directions focus on hybrid catalysts, integrated biorefineries, microalgae-based closed-loop systems, and decentralized processing. As supported by recent studies, implementing carbon-neutral cultivation and circular bioeconomy principles offers the most promising pathway toward sustainable biodiesel production.

Impact of Envelope Retrofitting Measures on a Building’s Life Cycle Greenhouse Gas Emissions: a case study in India

Predicting greenhouse gases emissions from decentralized composting by applying explainable machine learning method.

Abstract The decarbonization of the aviation sector is a critical component in global efforts to mitigate climate change, with aviation fuel emerging as a key enabler for reducing lifecycle greenhouse gas emissions. The hydroprocessing of non-edible oils offers a promising route, as it is compatible with existing fuel infrastructure and can utilize low-cost, renewable feedstocks that do not compete with food crops. This mini review explores the current landscape of hydroprocessed non-edible-oils for aviation fuel production, focusing on key challenges and future opportunities. Hydroprocessed esters and fatty acids are the most commercially advanced technologies for producing aviation fuel, and non-edible-oils have gained increasing attention. However, several barriers hinder the large-scale deployment of hydroprocessed non-edible-oil-based aviation fuel, including feedstock availability, land use concerns, low oil yields, and the need for pretreatment due to impurities. Technological challenges also persist in optimizing hydroprocessing conditions to enhance product selectivity, improve catalyst performance, and reduce hydrogen consumption. Additionally, integrating hydroprocessed aviation fuel derived from non-edible oils requires careful consideration of feedstock availability, land-use concerns, low oil yields, and the need for pretreatment to remove impurities. Incorporating these feedstocks into biorefineries alongside other waste streams can further enhance process economics and sustainability. Policies such as carbon credits, renewable fuel standards, and international sustainability certification schemes can further incentivize the development and commercialization of derived aviation fuel. This review highlights the critical need for interdisciplinary research, supportive policy frameworks, and investment in infrastructure to unlock the full potential of hydroprocessed non-edible oils in the transition toward sustainable aviation.

Abstract This systematic review evaluates life cycle greenhouse gas emissions from geothermal electricity generation, with a focus on hydrothermal flash, hydrothermal binary, and enhanced geothermal systems. By screening 169 studies published since 2017, 24 met the inclusion criteria and were analyzed alongside Pre-2017 benchmarks. Results indicate median life cycle emissions of 43 g CO2 eq/kWh for hydrothermal flash, 36 g CO2 eq/kWh for enhanced geothermal, and 30 g CO2 eq/kWh for hydrothermal binary. Compared with fossil fuels, these values remain substantially lower, underscoring the role of geothermal in low-carbon energy transitions. Evidence suggests that emissions are declining during the construction phase due to advances in drilling efficiency and modular plant design, while operational emissions remain stable, reflecting the limited deployment of carbon capture. End-of-life recycling varies between technologies. These findings highlight geothermal energy’s capacity to support resilient, circular, and sustainable power systems.

Biological processes underpin centralized wastewater treatment but are difficult to deploy at a small scale. Thermomechanical and thermochemical approaches could enable household-level sanitation, yet their economic and environmental potential remains unclear. We assessed two prototype household reinvented toilets (HRTs), with either pasteurization mechanical dewatering (PMD) and supercritical water oxidation (SCWO) treatment processes, using integrated process simulation, techno-economic analysis, and life cycle assessment under uncertainty. The total annualized expenditures (including capital and operating) are 1.41-1.87 (5th to 95th percentiles) and 1.85-2.45 USD·cap-1·day-1 for PMD and SCWO, respectively, placing both at the high end of global centralized treatment prices. The life cycle greenhouse gas (GHG) emissions span 321-452 and 362-520 kg CO2-eq·cap-1·year-1 for PMD and SCWO, respectively, with the grid electricity contributing 87-90% in both HRTs. Poor solid-liquid separation disproportionately increases costs and GHG emissions for SCWO relative to PMD. In the short term, optimizing a few levers─number of users, flush water volume, and the detailed design of the SCWO unit─can significantly reduce cost and emissions. In the long term, operating at maximum efficiency reduces both cost and emissions by approximately 70%. Deployment in locations with low wage, low-carbon electricity, low price levels, and large household sizes offers the greatest potential, positioning HRTs as viable advanced decentralized sanitation options in specialized settings.

Abstract While decarbonizing road transport is crucial for global climate goals, there is limited quantitative evidence on the economic viability and life-cycle emissions of low-carbon passenger vehicles in Africa, where motorization is rising. Here we study the economic cost and life-cycle greenhouse gas emissions of low-carbon passenger transport in Africa across six segments in 52 African countries through 2040. Using Monte Carlo and optimization models, we compare the total cost of ownership and life-cycle greenhouse gas emissions of battery electric vehicles powered by solar off-grid systems and synthetic fuelled vehicles to that of fossil-fuelled ones, neglecting policy-induced cost distortions. Whereas past reports suggested fossil fuel vehicles would dominate in Africa by mid-century, our results show that battery electric vehicles with solar off-grid chargers will have lower costs and negative greenhouse gas abatement costs well before 2040 in most countries and segments. Financing is identified as the key action point for governments and global financial institutions to accelerate Africa’s transition to battery electric vehicles with solar off-grid charging offering a cost-effective, viable solution to electricity infrastructure challenges.

We evaluate cradle-to-gate lifecycle greenhouse gas emissions for each U.S. steel production plant in 2022, accounting for uncertainty and spatial heterogeneity in ironmaking and steelmaking technologies, supply chain network dynamics, and material, fuel, and electricity supply. In 2022, the U.S. produced 81 million metric tons (mmt) of raw steel, with associated lifecycle emissions of 102 million metric tons of carbon dioxide equivalent (mmt CO2e), with 95 mmt emitted domestically. The largest emission source is on-site combustion and processes at steel plants (49% of total emissions), followed by raw material plant operations and transport (23%) and off-site electricity generation (15%). Plant-level lifecycle emission intensities range from 0.4 to 2.5 mt CO2e per mt raw steel produced across plants. Across steel production pathways, basic oxygen furnace (BOF) and electric arc furnace (EAF) plants have production-weighted average emission intensities of 2.0 and 0.8 mt CO2e per mt raw steel produced, respectively. Emission intensities also vary across geographies and firms due to differences in supply chains, electricity supply, and production technologies. This study provides important insights for assessing climate mitigation pathways, investment decisions, and policies.

Abstract Biofuel mandates can impact the environment in multiple ways that may be positive or negative, including affecting life-cycle greenhouse gas (GHG) emissions by displacing fossil fuels, affecting soil carbon stocks due to accompanying land use change, and water quality due to changes in fertilizer requirements and the mix of crops used as feedstocks. To achieve desired environmental outcomes in the presence of a biofuel mandate, additional policy instruments must be adopted to supplement the mandate. We develop an integrated and spatially explicit ecosystem-economic modeling framework to analyze the cost-effectiveness of alternative policies to achieve desired targets for GHG emissions reduction from the agricultural and fuel sectors in the USA and nitrate leaching reduction in the Gulf of Mexico below the levels that would be achieved by a corn ethanol and/or a cellulosic ethanol mandate in the USA. We find that while a corn ethanol mandate lowers GHG emissions, it increases nitrate leaching due to the expansion of corn production; a cellulosic ethanol mandate lowers both GHG emissions and nitrate leaching relative to a corn ethanol mandate, but the additional carbon and nitrate prices are needed to achieve anticipated GHG reduction and nitrate reduction targets. We also find that accompanying a biofuel mandate with a GHG reduction target alone leads to substantial nitrate reduction co-benefits, but a nitrate reduction target alone is less effective in reducing GHG emissions. Combining a GHG standard with a nitrate standard can achieve GHG and nitrate reduction targets at lower carbon and nitrate prices as compared to implementing each of these policies independently. Our findings show that disregarding policy co-benefits can overestimate the GHG and nitrate prices needed to achieve policy targets and higher policy costs.

The EPBD 2024 recast sets the deadline for new Zero-Emission Building standards for all new publicly owned buildings to 2028 and to 2030 for all new buildings. In the scope of Life Cycle Assessment stages, all steps resulting in major emissions from buildings must be considered and presented. The research evaluates the life cycle greenhouse gas emissions of a single-family house, focusing on diverse construction types and the hourly method of the annual energy calculations for continental and coastal climate areas in Croatia under the upcoming standards. Embodied carbon of diverse construction types was compared mutually, and required steps to meet the operational zero-emission standards were analyzed. Embodied energy of a 137.0 m2 family house built out of reinforced concrete results in up to 67 tons of CO2eq emissions, while wood in cross-laminated timber structures absorbs more carbon than emitted for all other materials and construction processes—23 tons of CO2eq. Regarding operational energy and accompanying emissions, in order to cost-effectively meet future ZEB standards in Croatia and offset the remaining operational emissions, photovoltaic systems of up to 2.5 kWp are required in continental areas and 1.6 kWp in coastal regions.

This study applies life cycle assessment (LCA) to quantify and compare the environmental impacts of battery electric vehicles (BEVs) and internal combustion engine vehicles (ICEVs) operated under different national electricity mixes, using Slovenia and selected European countries as case studies. The analysis utilizes the Ecoinvent database and the Environmental Footprint 3.1 (EF 3.1) impact assessment method, implemented in SimaPro, with a functional unit of 100 km of passenger car transport. Results show that BEV life cycle greenhouse gas emissions are highly sensitive to national grid carbon intensity, with coal-intensive mixes yielding BEV climate change impacts that are close to or higher than those of ICEVs. In contrast, low-carbon, renewable-based mixes substantially improve BEV performance in the climate change category. The highest life cycle greenhouse gas (GHG) emissions of BEV per 100 km of transport among the analyzed countries were in the case of Serbia, which mainly produces electricity from thermal power plants (20.9 kg CO2-eq), compared to Norway with 0.44 kg CO2-eq. Increasing the share of photovoltaics in Slovenia's electricity mix reduces the life cycle climate impacts of BEV use but slightly increases mineral and metal resource use, indicating a burden-shifting trade-off between decarbonization and material demand. The findings demonstrate that country-specific electricity mixes, when assessing environmental performance, need to be taken into account. Support policies that combine grid decarbonization, smart charging aligned with low-carbon hours, and improved battery and PV material circularity should be adopted to maximize the sustainability benefits of BEVs.

The import of renewable gases is considered an essential step towards achieving the climate targets of many countries in Europe and Asia. The EU Commission demands that renewable hydrogen (carriers) must achieve a 70 % reduction in emissions over their life cycle compared to fossil hydrogen. In recent years, numerous studies have therefore been published that evaluate the production and subsequent transportation of gaseous and liquid hydrogen (GH2/LH2), ammonia (NH3), liquid organic hydrogen carriers (LOHC), methanol, dimethylether and substitute natural gas (SNG) from an ecological perspective. Given the high degree of freedom in the methodology of life cycle assessment (LCA), however, their results are highly dependent on the respective system boundaries and assumptions. This review summarizes and discusses the different findings of those studies, aiming at identifying trends and main drivers in greenhouse gas emissions. The results show that renewable gases can contribute to a significant reduction in greenhouse gas emissions compared to natural gas. The main driver of emissions is the electricity mix used for hydrogen production and subsequent processing. This shows that the production of GH2 has lower emissions than other derivatives. Due to the low energy density, this advantage predominates up to a transport distance of 1500 km. Beyond these distances hydrogen (carriers) with high energy densities, such as LH2 or NH3, prove to be advantageous. LOHCs have very high emissions due to the energy-intensive dehydrogenation process. Previous studies have shown great potential for emissions reduction, particularly with hydrogen derivatives that require green carbon. However, further research is needed as many production pathways have not yet been considered. • Review of LCAs of imported hydrogen and hydrogen carriers is presented. • Renewable gas imports can make a decisive contribution towards achieving climate targets. • Provision of electricity in hydrogen generation and processing heavily influences the greenhouse gas emissions. • Pipeline transportation is preferable for short distances (up to 1500 km), beyond that shipping is more suitable.

Life-cycle greenhouse gas emissions analysis of battery-grade lithium production in Finland

A critical meta-survey of the lifecycle greenhouse gas emissions of hydrogen energy systems

The rapid growth and seasonal availability of agricultural materials, such as straws, stalks, husks, shells, and processing wastes, present both a disposal challenge and an opportunity for renewable fuel production. Solar-assisted thermochemical conversion, such as solar-driven pyrolysis, gasification, and hydrothermal routes, provides a pathway to produce bio-oils, syngas, and upgraded chars with substantially reduced fossil energy inputs compared to conventional thermal systems. Recent experimental research and plant-level techno-economic studies suggest that integrating concentrated solar thermal (CSP) collectors, falling particle receivers, or solar microwave hybrid heating with thermochemical reactors can reduce fossil auxiliary energy demand and enhance life-cycle greenhouse gas (GHG) performance. The primary challenges are operational intermittency and the capital costs of solar collectors. Alongside, machine learning (ML) and AI tools (surrogate models, Bayesian optimization, physics-informed neural networks) are accelerating feedstock screening, process control, and multi-objective optimization, significantly reducing experimental burden and improving the predictability of yields and emissions. This review presents recent experimental, modeling, and techno-economic literature to propose a unified classification of feedstocks, solar-integration modes, and AI roles. It reveals urgent research needs for standardized AI-ready datasets, long-term field demonstrations with thermal storage (e.g., integrating PCM), hybrid physics-ML models for interpretability, and region-specific TEA/LCA frameworks, which are most strongly recommended. Data’s reporting metrics and a reproducible dataset template are provided to accelerate translation from laboratory research to farm-level deployment.