Search Results (59)

The sustainability of the natural gas-to-methanol (NGTM) and methanol-to-gasoline (MTG) processes are assessed in this systematic review as a potential substitute in the global energy transition. Methanol offers itself as a versatile and less carbon-intensive substitute for conventional gasoline in light of growing environmental concerns and the demand for cleaner fuels. This review’s rationale is to assess MTG’s ability to lessen environmental impact while preserving compatibility with current fuel infrastructure. The goal is to examine methanol and gasoline’s effects on the environment, society, and economy throughout their life cycles. This review used a two-phase systematic literature review methodology, filtering and evaluating studies that were indexed by Scopus using bibliometric and thematic analysis. A total of 25 documents were reviewed, in which 22 documents analyzed part of this study, and 68% employed LCA or techno-economic analysis, with the U.S. contributing 35% of the overall publications. A comparative analysis of the reviewed literature indicates that methanol-based fuels offer significantly lower greenhouse gas (GHG) emissions and life cycle environmental impacts than gasoline, particularly when combined with carbon capture and renewable feedstocks. This review also highlights benefits, such as improved safety and energy security, while acknowledging challenges, including high production costs, infrastructure adaptation, and toxicity concerns. Several drawbacks are high manufacturing costs, the necessity to adjust infrastructure, and toxicity issues. The report suggests investing in renewable methanol production, AI-driven process optimization, and robust legislative frameworks for integrating green fuels. The life cycle sustainability assessment (LCSA) of NGTM and MTG systems should be investigated in future studies, particularly in light of different feedstock and regional circumstances. The findings emphasize NGTM and MTG’s strategic role in aligning with several UN Sustainable Development Goals (SDGs) and add to the worldwide conversation on sustainable fuels. A strong transition necessitates multi-stakeholder cooperation, innovation, and supporting policies to fully realize the sustainability promise of cleaner fuels like methanol. Full article

The life-cycle economics and greenhouse-gas (GHG) emissions of forest biomass harvesting and utilization for value-added bioproducts were comprehensively evaluated via the development of an integrated modeling framework. Taking the eastern U.S. as the case region, the model innovatively integrated field studies, a Bayesian-based statistical learning model, techno-economic analysis, and life-cycle assessment. In specific, by investigating and summarizing the typical forest biomass harvesting systems across the region, the forest biomass harvesting costs were spatially grouped and mapped for four classified subregions across the eastern US. Overall, with 95% confidence the forest biomass harvesting cost is between USD 21.99 and USD 44.33/dry Mg, while the GHG emissions are between 14.79 and 98.80 kg CO₂ eq./dry Mg. Furthermore, for the forest biomass utilization for four alternative value-added bioproducts, the minimum selling price (MSP) is USD 177.82/Mg for pellet fuel, USD 110.24/MWh for biopower, USD 1059.4/Mg for biochar, and USD 4.98/gallon for aviation fuel. The life-cycle GHG emissions are 149.80 kg CO₂ eq./Mg pellet fuel, 52.22 kg CO₂ eq./MWh biopower, 792.12 kg CO₂ eq./Mg biochar, and 2.13 kg CO₂ eq./gallon aviation fuel, respectively. Considering the uncertainties, 95% confidence intervals of MSPs range from USD 164.77 to USD 190.97/Mg for pellet fuel with an 81.85% probability to be profitable, from USD 100.20 to USD 120.21/MWh for biopower with a 49.38% probability to be profitable, from USD 1000.91 to USD 1109.25/Mg for biochar with a 79.51% probability to be profitable, from USD 4.86 to USD 5.54/gallon for aviation fuel with an 0.03% probability to be profitable. Moreover, the MSPs of pellet fuel and biochar are much less affected by the market changes than those of biopower and aviation fuel. However, the production of biopower and aviation fuel has lower carbon intensities than that of pellet fuel and biochar. Full article

This study investigates the carbon dioxide (CO₂) emission characteristics of using torrefied biomass (residual wood and wood chip) as co-firing materials in coal-fired power plants, based on life cycle assessment techniques. We quantify the greenhouse gas (GHG) mitigation potential of substituting coal with biomass under different torrefaction temperatures, biomass types, and co-firing ratios. Results indicate that higher co-firing ratios significantly reduce CO₂ emissions. Torrefaction at 270 °C was identified as optimal, balancing high energy yield and minimized emissions, while 310 °C torrefaction showed limited mitigation benefits due to lower mass yields and higher carbon content. Pelletization and torrefaction enhanced biomass properties, but the energy intensity of these processes affected the overall emission balance. This study underscores the potential of biomass to replace imported coal and contribute to carbon neutrality, while highlighting the importance of optimizing biomass processing conditions. Future work should focus on refining torrefaction parameters and assessing other biomass characteristics to enhance operational efficiency in coal-fired power plants. Full article

Livestock farming is an activity closely linked to the environment, directly affecting its surrounding ecosystem while utilizing the natural resources it provides. Accordingly, it is essential to study these production systems in order to implement more sustainable models that allow for a balance between socioeconomic and environmental factors. The main objective of this study was to analyze the environmental impact of nine different dairy goat production systems located in northern Extremadura, Spain. The selected farms ranged from extensive and organic production models to more intensive ones. The methodology used was a life cycle assessment (LCA) to calculate the carbon footprint, following the IPCC (Intergovernmental Panel on Climate Change) guidelines. A comprehensive evaluation of emissions was conducted, considering the different global warming potentials (GWPs) established by the IPCC for the main gases associated with livestock farming. In addition, carbon sequestration (C_seq) was incorporated into the analysis to assess the contribution of goat farming to climate change mitigation based on its production management. CH₄ emissions were the main source (44–67%) of GHGs, followed by CO₂ from inputs (20–48%), and finally N₂O (7–13%). A trend was observed linking increased CH₄ emissions to more extensive and less productive livestock systems. However, the significant role of soil as a carbon sink was highlighted, as it greatly offsets the emissions produced, demonstrating its potential mitigation due to C_seq, particularly in more extensive models. The importance of this factor suggests that it should be taken into account in such studies to provide a realistic view of the final impact of each production system. Full article

Amidst the global shift towards a low-carbon development trajectory, the hickory industry in Lin’an District is progressively embracing green, low-carbon, and sustainable practices. This study, leveraging the life cycle assessment (LCA) methodology, meticulously scrutinizes the carbon footprint of the hickory industry by segmenting its life cycle into two distinct subsystems: the plantation and the factory. Through comprehensive, year-long monitoring of soil greenhouse gas (GHG) emissions in hickory plantations, our findings underscore that while total GHG emissions from eco-complex management (ECM) surpassed those of intensive management (IM) by 10.7% (p < 0.001), ECM significantly mitigated the carbon footprint per kilogram of hickory produced, achieving a reduction of 1.0495 kgCO₂eq. This advantage is primarily attributable to ECM’s diminished reliance on chemical fertilizers. Within the factory subsystem, when processing 1 kg of hickory, the digital factory incurred a carbon footprint of 2.5923 kgCO₂eq kg⁻¹, whereas family workshops exhibited a lower footprint of 1.9544 kgCO₂eq kg⁻¹. Notably, the processing and packaging stages collectively accounted for over 90% of the factory subsystem’s carbon emissions, with natural gas being the primary contributor during processing. To estimate the carbon emission reduction potential within the hickory industry, this research draws parallels with emission reduction strategies employed by other industries and outlines tailored strategies to propel its low-carbon development. By advocating for the widespread adoption of ECM and enhancing the energy efficiency of processing enterprises, the hickory industry can effectively diminish its carbon footprint and steer towards a green, low-carbon, and high-quality development paradigm. Full article

This study explores the water consumption and greenhouse gas (GHG) emissions in the Yarkand River Basin, focusing on their dynamic interactions across industrial sectors. Utilizing environmental input–output analysis (IOA), the CROPWAT model, and life cycle assessment (LCA), we quantified the historical evolution of physical and virtual water cycles in relation to the water–carbon nexus. Our findings reveal that the planting industry, particularly the production of export-oriented, water-intensive crops like cotton, significantly contributes to both blue and green water consumption, exacerbating regional water scarcity. The persistent external market demand drives this over-extraction, further strained by the basin’s limited water retention capabilities. Although advancements have been made in reducing the per-unit water footprint of crops, total water consumption continues to rise due to agricultural expansion, intensifying pressure on blue water resources. Additionally, agricultural GHG emissions have surged, driven by increased electricity consumption, heavy fertilizer use, and escalating soil N₂O emissions. In light of these challenges, our research underscores the critical need for integrated resource management strategies that align with sustainable development goals. By promoting efficient water allocation within the agricultural sector and diversifying crop structures downstream, we can enhance ecosystem resilience and reduce environmental degradation. Furthermore, the advancement of value-added agricultural processing and the implementation of innovative water conservation technologies are essential for fostering economic sustainability. These strategies not only mitigate the environmental impacts associated with agricultural practices but also strengthen the region’s adaptive capacity in the face of climate change and fluctuating market demands. Our findings contribute to the broader discourse on sustainable agricultural practices, emphasizing the interconnectedness of water management, climate resilience, and economic viability in arid regions. Full article

This study evaluates the greenhouse gas (GHG) impacts of converting municipal solid waste (MSW) into methanol, focusing on both landfill methane (CH₄) emission avoidance and the provision of cleaner liquid fuels with lower carbon intensity. We conduct a life cycle assessment (LCA) to assess potential GHG reductions from MSW gasification to methanol, enhanced with hydrogen produced via natural gas pyrolysis or water electrolysis. Hydrogen enhancement effectively doubles the methanol yield from a given amount of MSW. Special attention is given to hydrogen production through natural gas pyrolysis due to its potential for lower-cost hydrogen and reduced reliance on renewable electricity compared to electrolytic hydrogen. Our analysis uses a case study of methanol production from an oxygen-fired entrained flow gasifier fed with refuse-derived fuel (RDF) simulated in Aspen HYSYS. The LCA incorporates the significant impact of landfill methane avoidance, particularly when considering the 20-year global warming potential (GWP). Based on the LCA, the process has illustrative net GHG emissions of 183 and 709 kgCO_2e/t MeOH using renewable electricity for electrolytic hydrogen and pyrolytic hydrogen, respectively, for the 100-year GWP. The net GHG emissions using 20-year GWP are −1222 and −434 kgCO_2e/t MeOH, respectively. Additionally, we analyze the sensitivity of net GHG emissions to varying levels of fugitive methane emissions. Full article

Due to climate change risks, the public, regulators, and investors require solid actions to minimize the greenhouse gas (GHG) emissions of mineral extraction and metals production. The mining sector considers alternatives to reduce its carbon footprint by transforming the business and adopting new technologies into operations. Given the capital intensity, technical characteristics, and business structure involved, a shift in the mining industry necessitates impartial insights into the trade-offs and risks. Considering the low-carbon transition trade-offs and risks in mining, this study presents the application of system dynamics modeling (SDM) in mining projects to analyze the impact of decarbonization alternatives with respect to carbon footprint and costs. A system dynamics model of an open-pit copper mine is developed to quantify greenhouse gas (GHG) emissions, as well as capital and operational costs, during the project life cycle. The change in GHG emissions in the business-as-usual scenario with diesel equipment haulage versus the alternative scenario with electric overland conveyor haulage is compared concerning GHG emissions and associated costs. The results unequivocally demonstrated that electrifying material mobility offers significant decarbonization in open-pit mining if the on-site electricity has a low emission factor. The findings also indicate that the substantial cost difference between electrification and diesel alternatives is another major obstacle to implementing electrification in an open-pit copper mine. This research proves that implementing SDM in the mining industry can offer impartial insights into decision-making and enable a thorough evaluation of options using quantitative criteria. It effectively assesses and communicates the trade-offs and risks of transitioning to low-carbon alternatives because it analyzes project variables quantitatively and holistically and is easy to run. Full article

While electric vehicles (EVs) offer lower life cycle greenhouse gas emissions in some regions, the concern over the greenhouse gas emissions generated during battery production is often debated. This literature review examines the true environmental trade-offs between conventional lithium-ion batteries (LIBs) and emerging technologies such as solid-state batteries (SSBs) and sodium-ion batteries (SIBs). It emphasizes the carbon-intensive nature of LIB manufacturing and explores how alternative technologies can enhance efficiency while reducing the carbon footprint. We have used a keyword search technique to review articles related to batteries and their environmental performances. The study results reveal that the greenhouse gas (GHG) emissions of battery production alone range from 10 to 394 kgCO₂ eq./kWh. We identified that lithium manganese cobalt oxide and lithium nickel cobalt aluminum oxide batteries, despite their high energy density, exhibit higher GHGs (20–394 kgCO₂ eq./kWh) because of the cobalt and nickel production. Lithium iron phosphate (34–246 kgCO₂ eq./kWh) and sodium-ion (40–70 kgCO₂ eq./kWh) batteries showed lower environmental impacts because of the abundant feedstock, emerging as a sustainable choice, especially when high energy density is not essential. This review also concludes that the GHGs of battery production are highly dependent on the regional grid carbon intensity. Batteries produced in China, for example, have higher GHGs than those produced in the United States (US) and European Union (EU). Understanding the GHGs of battery production is critical to fairly evaluating the environmental impact of battery electric vehicles. Full article

Brazilian agriculture is constantly questioned concerning its environmental impacts, particularly greenhouse gas (GHG) emissions. This research study used data from a 34-year field experiment to estimate the life cycle GHG emissions intensity of maize production for grain in farming systems under no-tillage (NT) and conventional tillage (CT) combined with Gramineae (oat) and legume (vetch) cover crops in southern Brazil. We applied the Feedstock Carbon Intensity Calculator for modeling the “field-to-farm gate” emissions with measured annual soil N₂O and CH₄ emissions data. For net CO₂ emissions, increases in soil organic C (SOC) were applied as a proxy, where the CT combined with oat was a reference. The life cycle GHG emissions intensity for maize was negative under NT farming systems with Gramineae and legume cover crops, −0.7 and −0.1 kg CO₂e kg⁻¹ of maize, respectively. CT with oats as a cover crop had a GHG intensity of 1.0 kg CO₂e kg⁻¹ of maize and 2.2 Mg CO₂e ha⁻¹. NT with cover crops increased SOC (0.7 C Mg ha⁻¹ yr⁻¹, 0–100 cm) and contributed to the mitigation of life cycle GHG emissions of maize production. This research shows that NT with cover crops is a sustainable solution for farming in southern Brazil. Full article

Lifecycle analysis was used to estimate well-to-wheel greenhouse gas (GHG) emissions associated with the production, transport, and use of oxygenated gasoline in Colombia, Japan, and France. The study evaluated fuel blends containing ethanol and/or ethyl tertiary-butyl ether (ETBE) that aligned with oxygen and octane specifications currently in place or under consideration for each country. For Colombia, fuel blends meeting a 3.7 wt.% oxygen specification were analyzed using ethanol sourced and produced in the U.S. from corn and in Colombia from sugarcane, and ETBE processed in the U.S. Gulf Coast. For Japan, blends with 1.3, 2.7 and 3.7 wt.% oxygen were analyzed using ethanol sourced and produced in the U.S. and Brazil, and ETBE processed in the U.S. Gulf Coast. For France, oxygenated gasoline blends with 3.7 to 8.0 wt.% oxygen content were analyzed with ethanol produced locally from corn, beet, and wood and imported sugarcane ethanol. Data were populated from both publicly available secondary data sources and new primary data developed for ETBE production in the U.S. and Europe. This study also accounted for distinct lifecycle emissions among gasoline components, focused on aromatic-rich reformate used to boost octane in non-oxygenated fuels. Across each country, results indicate that the replacement of reformate in ethanol-free (E0) gasoline with oxygenates up to 3.7 wt.% oxygen reduces lifecycle GHG emissions by 6–9%, with the highest GHG reduction provided when ETBE alone is used for oxygenate. For higher oxygen blends modeled for France, the highest GHG reduction (19%) was for a blend of 51 vol.% ETBE to achieve 8.0 wt.% oxygen, the equivalent of E23 (gasoline with 23 vol.% ethanol). Overall, displacing ethanol with ETBE to achieve a fixed oxygen level increased GHG benefits relative to ethanol-only blends, owing to the greater volume of the carbon-intensive reformate displaced. Full article

This research conducted a probabilistic life-cycle assessment (pLCA) into the greenhouse gas (GHG) emissions performance of nine combinations of truck size and powertrain technology for a recent past and a future (largely decarbonised) situation in Australia. This study finds that the relative and absolute life-cycle GHG emissions performance strongly depends on the vehicle class, powertrain and year of assessment. Life-cycle emission factor distributions vary substantially in their magnitude, range and shape. Diesel trucks had lower life-cycle GHG emissions in 2019 than electric trucks (battery, hydrogen fuel cell), mainly due to the high carbon-emission intensity of the Australian electricity grid (mainly coal) and hydrogen production (mainly through steam–methane reforming). The picture is, however, very different for a more decarbonised situation, where battery electric trucks, in particular, provide deep reductions (about 75–85%) in life-cycle GHG emissions. Fuel-cell electric (hydrogen) trucks also provide substantial reductions (about 50–70%), but not as deep as those for battery electric trucks. Moreover, hydrogen trucks exhibit the largest uncertainty in emissions performance, which reflects the uncertainty and general lack of information for this technology. They therefore carry an elevated risk of not achieving the expected emission reductions. Battery electric trucks show the smallest (absolute) uncertainty, which suggests that these trucks are expected to deliver the deepest and most robust emission reductions. Operational emissions (on-road driving and vehicle maintenance combined) dominate life-cycle emissions for all vehicle classes. Vehicle manufacturing and upstream emissions make a relatively small contribution to life-cycle emissions from diesel trucks (<5% each), but these are important aspects for electric trucks (5% to 30%). Full article

The energy intensity and high emissions of extractive industries bring a major need for decarbonisation actions. In 2021, extraction and primary processing of metals and minerals were responsible for 4.5 Gt of equivalent CO₂. The aluminium industry specifically accounted for total emissions of 1.1 Gt CO₂ eq. per year. Reaching the European milestone of zero emissions by 2050, requires a 3% annual reduction. To achieve this, the industry has searched for innovative solutions, considering the treatment of emitted CO₂ with techniques such as Carbon Capture Utilisation and Storage (CCUS), or the prevention of CO₂ formation on the first place by utilising alternative fuels such as hydrogen (H₂). This study aims to comprehensively compare the overall environmental performance of different strategies for addressing not only greenhouse gas (GHG) emission reduction potential, but also emissions to air in general, as well as freshwater and terrestrial ecotoxicity, which are commonly overlooked. Specifically, a Life Cycle Assessment (LCA) is conducted, analysing four scenarios for primary Al production, utilising (1) a combination of fossil fuels, specifically Natural Gas (NG), Light Fuel Oil (LFO) and Heavy Fuel Oil (HFO) (conventional approach); (2) carbon capture and geological storage; (3) Carbon Capture and Utilisation (CCU) for methanol (MeOH) production and (4) green H₂, replacing NG. The results show that green H₂ replacing NG is the most environmentally beneficial option, accounting for a 10.76% reduction in Global Warming Potential (GWP) and 1.26% in Photochemical Ozone Formation (POF), while all other impact categories were lower compared to CCUS. The results offer a comprehensive overview to support decision-makers in comparing the overall environmental impact and the emission reduction potential of the different solutions. Full article

Presented in this study is a comparative life cycle assessment of 60 wind plant systems’ GHG intensities (49 of onshore and 11 of offshore) in China with regard to different geographical location, turbine technology and management level. As expected, geographical location and turbine technology affect the results marginally. The result shows that the life-cycle GHG intensities of onshore and offshore cases are 5.84–16.71 g CO₂eq/kWh and 13.30–29.45 g CO₂eq/kWh, respectively, which could be decreased by 36.41% and 41.30% when recycling materials are considered. With wind power density increasing, the GHG intensities of onshore cases tend to decline, but for offshore cases, the larger GHG intensity is as the offshore distance increases. The GHG intensities of onshore cases present a decreasing trend along with the technical advancement, and offshore counterparts is around 65% higher than the onshore cases in terms of wind turbines rated at more than 3 MW. The enlarging of offshore turbine size does not necessarily bring marginal benefit as onshore counterparts due to the increasing cost from construction and maintenance. After changing the functional unit to 1 kWh on-grid electricity (practical), the highest GHG intensities of Gansu province increase to 17.94 g CO₂eq/kWh, same as other wind resource rich provinces, which significantly offsets their wind resource endowment. The results obtained in this study also highlight the necessity for policy interventions in China to enhance resource exploration efficiency and promote robust and sustainable development of the wind power industry. Full article

Cellulose hydrolysis to glucose using a heterogeneous catalyst is a necessary step in producing bio-based chemicals and polymers. The requirement for energy-intensive pretreatments, such as ball milling, to increase the reactivity of cellulose is one of the major issues in this area. Here, we show that by using solvent-assisted adsorption as a pretreatment step, cellulose can be adsorbed on the surface of a carbon catalyst. For adsorption pretreatment, phosphoric acid (H₃PO₄) performed better than other solvents such as sulfuric acid (H₂SO₄), tetrabutylammonium fluoride/dimethyl sulfoxide (TBAF/DMSO) and 1-butyl-3-methylimidazolium chloride ([BMMI]Cl). Hydrolysis after the adsorption of cellulose and the removal of H₃PO₄ produced a 73% yield of glucose. Partial hydrolysis of cellulose in H₃PO₄ before adsorption increased the final glucose yield. The glucose yield was proportional to the number of weakly acidic functional groups on the carbon catalyst, indicating the reaction was heterogeneously catalyzed. In a preliminary lab-scale life-cycle analysis (LCA), greenhouse gas (GHG) emissions per kg of glucose produced through the hydrolysis of cellulose were calculated. The H₃PO₄-assisted adsorption notably reduces GHG emissions compared to the previously reported ball milling pretreatment. Full article