Greenhouse Gas Mitigation Research Articles

Scope 2 estimates of carbon dioxide emissions from electricity consumption at the US census block group scale

This paper introduces and describes a dataset representing United States carbon dioxide (CO2) emissions from electricity consumption (scope 2 CO2 emissions) for the 2019–2021 time period separately for the residential, commercial, and industrial sectors. The spatial resolution is the U.S. census block group at annual time resolution. We also provide state-scale aggregate data. Given the increased interest in greenhouse gas mitigation at the urban landscape scale, this data offers the opportunity to better understand the emitting landscape and craft more targeted, efficient policy instruments. The approach starts with well-established estimates of scope 2 CO2 emissions at larger scales and performs a series of downscaling steps to allocate scope 2 emissions into block groups. This open-access scope 2 CO2 emissions dataset and methodology is valuable for a wide range of multidisciplinary studies, including climate science, environmental policy, urban planning, and socioeconomic research.

Understanding Chinese Farmers’ Behavioral Intentions to Use Alternative Fuel Machinery: Insights from the Technology Acceptance Model and Theory of Planned Behavior

Mitigating greenhouse gas emissions and reducing fossil fuel dependence have heightened interest in alternative fuels, particularly in agriculture, a key energy-intensive sector. This study investigates the use of the Technology Acceptance Model and the Theory of Planned Behavior to analyze Chinese farmers’ behavioral intentions to adopt alternative fuel machinery. In 2023, a total of 281 full-time farmers were sampled from Jiangsu, Sichuan, and Hebei provinces, followed by path analysis conducted using PLS-SEM. The results underline that perceived usefulness β = 0.369, p < 0.001, and social norms β = 0.185, p < 0.001 are strong drivers for the adoption of alternative fuel machinery, while perceived barriers to operate and infrastructure gaps act as inhibitors. Also, perceived benefits β = 0.235, p = 0.002, and perceived behavior control β = 0.157, p = 0.027 positively predict behavior intentions. This thus suggests that improvement in the technological infrastructure and increasing farmers’ awareness of the practical and economic benefits of alternative fuel machinery could result in a serious increase in adoption rates. This study does have weaknesses, as its focus on 50 mid-sized farms in the Midwest and utilization of self-reported data may limit the generalizability of its findings. This study, however, has major implications for policy and manufacturers to underscore the fact that targeted interventions through subsidies, training programs, and infrastructural development would be necessary to permit a transition toward sustainable energy in agriculture.

Impact of Biochar on Nitrogen-Cycling Functional Genes: A Comparative Study in Mollisol and Alkaline Soils

Biochar has gained considerable attention as a sustainable soil amendment due to its potential to enhance soil fertility and mitigate nitrogen (N) losses. This study aimed to investigate the effects of biochar application on the abundance of key N-cycling genes in Mollisol and alkaline soils, focusing on nitrification (AOA, AOB, and nxrB) and denitrification (narG, norB, and nosZ) processes. The experiment was conducted using soybean rhizosphere soil. The results demonstrated that biochar significantly altered the microbial community structure by modulating the abundance of these functional genes. Specifically, biochar reduced narG and nosZ abundance in both soil types, indicating a potential reduction in N2O emissions. In contrast, it promoted the abundance of nxrB, particularly in alkaline soils, suggesting enhanced nitrite oxidation. The study also revealed strong correlations between N-cycling gene abundances and soil properties such as pH, EC (electrical conductivity. Biochar improved soil pH and nutrient availability, creating favorable conditions for AOB and Nitrospira populations, which play key roles in ammonia and nitrite oxidation. Additionally, the reduction in norB/nosZ ratios in biochar-treated soils suggests a shift towards more efficient N2O reduction. These findings highlight biochar’s dual role in enhancing soil fertility and mitigating greenhouse gas emissions in Mollisol and alkaline soils. The results provide valuable insights into the sustainable management of agricultural soils through biochar application, emphasizing its potential to optimize nitrogen-cycling processes and improve soil health. Further research is needed to explore the long-term impacts of biochar on microbial communities and nitrogen-cycling under field conditions.

Life Cycle Assessment of Torrefied Residual Biomass Co-Firing in Coal-Fired Power Plants: Aspects of Carbon Dioxide Emission

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.

Advanced Control Strategies for Cleaner Energy Conversion in Biomass Gasification

The escalating climate crisis necessitates urgent and decisive action to mitigate greenhouse gas emissions. Gasification stands out as a highly adaptable process for energy conversion, capable of handling a wide range of feedstocks, from coal to biomass. The process plays a significant role in improving sustainability by converting these feedstocks into synthesic gas (syngas), which can be used as a cleaner energy source or as a building block for producing various chemicals. The utilization of syngas obtained through gasification not only reduces the reliance on fossil fuels but also helps in reducing greenhouse gases (GHGs), thereby contributing to a more sustainable energy landscape. To maintain optimal operational conditions and ensure the quality and safety of the product, an effective control system is crucial in the gasification process. This paper presents a comparative analysis of three control strategies applied to a numerical model of rice husk gasification: classical control, fuzzy logic control, and dynamic matrix control. The analysis is based on a comprehensive model that includes the equations necessary to capture the dynamic behavior of the gasification process across its various stages. The goal is to identify the most effective control strategy, and the performance of each control strategy is evaluated based on the integral of the absolute value of the error (IAE). The results indicatethat fuzzy logic control consistently outperforms classical control techniques, demonstrating superior disturbance rejection, enhanced stability, and overall improved control accuracy. These findings highlight the importance of selecting an appropriate advanced control strategy to optimize sustainable gasification processes.

Porous frameworks for uranium extraction from seawater

The utilization of uranium (U) fission energy as a high-density, clean power source plays a pivotal role in mitigating greenhouse gas emissions. Uranium extraction from seawater exhibits superior environmental friendliness compared to terrestrial uranium mining, as it avoids substantial generation of radioactive waste and harmful chemicals. However, conventional adsorbents such as fiber, polymer, and biomass materials exhibit slow adsorption rates and low ion selectivity. Porous frameworks with large inner surface, full host-guest interaction, and site utilization are utilized to improve uranium absorption performance. Consequently, devising and synthesizing materials that enable efficient and cost-effective extraction of U(VI) from seawater poses a formidable challenge. Recently, there has been a considerable surge in academic interest regarding the synthesis and design of porous frameworks. By integrating experimental data, spectroscopic analysis, and theoretical calculations, we have conducted an extensive investigation into the actual performance, underlying principles, and practicality of conventional materials (such as fibers) and novel porous materials serving as adsorbents, photocatalysts, and electrocatalysts for U(VI) extraction from seawater.

Electrochemical CO2 Fixation and Release Cycle Featuring a Trinuclear Zinc Complex for Direct Air Capture

AbstractCO2 capture technology can mitigate greenhouse gas emissions and global warming. CO2 capture driven by electrochemical reactions is attractive because the operation is carried out at normal temperature and pressure and involves a simple input system using electrical energy. Although promising metal complexes with high CO2 fixation performance have been reported, there are few studies on systems that combine electrochemical reactions and metal complexes. Here, we demonstrated stable CO2 fixation‐release cycles using an electrochemical system with trinuclear Zn(II) complex (Zn3L) as the CO2 fixative and an ionic liquid as a supporting electrolyte for the stable operation. This system showed a faster CO2 fixation rate than that of an aqueous alkaline solution at the same concentration. Continuous release and refixation of CO2 were achieved by decomposition and reconstruction of the complex structure induced by H+ and OH− supplied from a bipolar membrane equipped in the electrolytic cell. The CO2 fixation‐release cycle was demonstrated even for dilute CO2 (450 ppm) in air, where the CO2 capture rate reached approximately 46 % of CO2 contained in the air under an air flow condition of 200 mL ⋅ min−1. This case, combining electrochemical drive and metal complexes, will provide a new option for CO2 capture technology.

Assessing the Monetary Value and Environmental Impact of Household Food Waste in Italy

Household food waste accounts for a significant share of total food waste. In 2022, around 1.05 billion tons of food waste were generated—60% of which came from households. In the EU, households generate 54% of the total food waste. In Italy, according to a former diary study, avoidable household food waste accounts for 529.9 g per capita per week. Building on this data, this study assesses the monetary value of food waste at the household level in 6 provinces across the country, considering the prices of food items recorded by the Italian Observatory of market prices. Moreover, the environmental impacts of household food waste (greenhouse gas emissions, water consumed, and land used) were investigated based on existing data from well-grounded scientific literature. The results show that the monetary value of food waste ranges from EUR 357.43 to EUR 404.62 per household per year, corresponding to 5–7% of the average household expenditure for food. The environmental impacts per household per year account for 149 kgCO2eq, which contributes to climate change. In addition, household food waste is responsible for 303,498 L of water consumed and 1426 m2 of land used. The results of this study can be integrated into National Energy and Climate Plans (NECPs), to integrate food waste reduction into energy savings and greenhouse gas mitigation strategies.

Quantifying and Mitigating Greenhouse Gas Emissions in Egg-Laying Hen Farming: A Path Towards Carbon Neutrality

This study presents a comprehensive framework for assessing and mitigating greenhouse gas (GHG) emissions in commercial egg-laying hen farming in Uttaradit Province, with the aim of achieving carbon neutrality within the poultry sector. Employing a detailed life cycle assessment (LCA) over a 450-day production period, this research identifies key sources of emissions, with feed consumption identified as the largest contributor, followed by water use and energy demands. To address these emissions, the study explores several innovative strategies: transitioning to solar photovoltaic systems for lighting and water pumping, shifting from diesel to biodiesel for fuel, and optimizing feed compositions. Additionally, advanced manure management practices are proposed to reduce methane and nitrous oxide emissions. Collectively, these interventions could significantly diminish the emissions associated with hen farming operations, thereby advancing environmental sustainability. This work not only provides actionable insights for poultry farms seeking to lower their emissions but also offers a scalable and adaptable model with broader implications for sustainable practices across the agricultural sector. The findings underscore the importance of renewable energy integration, feed optimization, and efficient waste management in mitigating the environmental impact of agriculture, thereby informing both policy and practice in the pursuit of carbon-neutral food production.

Rhizosphere microecological mechanism of carbon sequestration and its emission mitigation in rice ratooning

Rice ratooning plays a critical role in mitigating global climate change and enhancing soil carbon sequestration due to its properties of carbon fixation and emission reduction. The rhizosphere micro-ecosystem emerges as one of the key determinants, thus it is highly significant to investigate the impact changes in rhizosphere microbial composition on the ecological mechanisms associated with carbon sequestration and emission reduction in paddy fields. Over two consecutive years, this study analyzed greenhouse gas emission characteristics, photosynthetic carbon assimilation patterns, and rhizosphere microenvironmental differences between the main crop (MC) and ratoon season rice (RSR) using four rice varieties with distinct growth stages and genetic traits. The results demonstrated that compared to MC, RSR reduced the daily average methane (CH₄) emissions from paddy field by 57.78∼64.31 %, while decreasing the distribution of photosynthetic products to the rhizosphere soil by 78.15 %. 16S rRNA sequencing revealed a significant increase in the abundance of autotrophic microorganisms, and the carbon-fixing bacterium Pseudarthrobacter was isolated and identified in RSR soil. The exogenous addition of this microorganism increased the soil organic carbon (SOC) content of RSR by 4.65 %, while simultaneously reducing CH₄ emissions from paddy fields by 26.25 %. The significant increase in autotrophic carbon-fixing bacteria in the rhizosphere soil is one of the key micro-ecological mechanisms driving carbon sequestration and emission reduction in paddy fields. This is attributed to the reduced allocation of photosynthetic carbon assimilation products to the belowground components, thereby promoting the abundance of autotrophic carbon-fixing bacteria in RSR field. Consequently, the ecological niche width of heterotrophic microorganisms, such as methanogens, is reduced, while autotrophic carbon-fixing bacteria mitigate greenhouse gas emissions from RSR field by fixing CO₂ and increasing SOC content. The findings offer valuable theoretical and practical perspectives on attaining the overarching objectives of carbon neutrality and food security.

Decarbonizing the Food System with Microbes and Carbon-Neutral Feedstocks.

Harnessing CO2 and CO2-derived C1-C2 compounds for microbial food production can mitigate greenhouse gas emissions and boost sustainability within the food sector. These innovative technologies support carbon neutrality by generating nutrient-rich edible microbial biomass and biocompounds using autotrophic and heterotrophic microbes. However, qualifying microbial food viability and future impacts in the food sector remains challenging due to their diversity, technical complexity, socioeconomic forces, and incipient markets. This review provides an overview of microbial food systems and then delves into the technical interplay among feedstocks, microbes, carbon fixation platforms, bioreactor operations, and downstream processes. The review further explores developing markets for microbial food products, the industrial landscape, economic drivers, and emerging trends in next-generation food products. The analysis suggests a transformative shift in the food industry is underway, yet significant challenges persist, such as securing cost-effective feedstocks, improving downstream processing efficiency, and gaining consumer acceptance. These challenges require innovative solutions and collaborative efforts to ensure the future commercial success of microbial foods-doing so will create myriad opportunities to transform and decarbonize our food system.

Impacts of Transition Piece Designs on the Resilience of Large Offshore Wind Turbines Subject to Combined Earthquake, Wind and Wave Loads and Soil‐Structure Interaction

ABSTRACTThe urgent global drive to mitigate greenhouse gas emissions has significantly boosted renewable energy production, notably expanding offshore wind energy across the globe. With the technological evolution enabling higher‐capacity turbines on larger foundations, these installations are increasingly situated in earthquake‐prone areas, underscoring the critical need to ensure their seismic resilience as they become a pivotal component of the global energy infrastructure. This study scrutinises the dynamic behaviour of a 15 MW offshore wind turbine (OWT) under concurrent earthquake, wind and wave loads, focusing on the performance of the ultra‐high‐strength cementitious grout that bonds the monopile to the transition piece. Employing LS DYNA for numerical simulations, we explored the seismic responses of four OWT designs with diverse transition piece cone angles, incorporating nonlinear soil springs to model soil‐structure interactions (SSIs) and conducting a site response analysis (SRA) to account for local site effects on ground motion amplification. Our findings reveal that transition pieces with larger cone angles exhibit substantially enhanced stress distribution and resistance to grout damage, evidenced by decreased ovalisation in the coned sections of the transition piece and monopile, and improved bending flexibility. The observed disparities in damage across different cone angles highlight shortcomings in current design guidelines pertaining to the prediction of grout stresses in conical transition piece designs, with the current code‐specified calculations predicting higher stresses for transition piece designs with larger cone angles. This study also highlights the code's limitations when accounting for grout damage induced by stress concentrations in the grouted connections under seismic dynamic loading conditions. The results of the study demonstrate the need for refinement of these guidelines to improve the seismic robustness of OWTs, thereby contributing to the resilience of renewable energy infrastructure against earthquake‐induced disruptions.

Circular economy, methane capture, and climate education in US HEIs

PurposeThis study aims to analyze the involvement of US colleges and universities in methane capture projects in the waste sector and their related educational initiatives aiming to build circular economies and reduce greenhouse gas (GHG) emissions.Design/methodology/approachThe authors compiled a subset of 22 “early adopting” institutions – those that received media attention for solid or liquid waste methane capture projects from 1999 to the present. The authors included all cases found within a reasonable number of queries. The institutions fell into two groups: (1) schools directly involved in gas capture projects, and (2) schools that purchased third-party offsets tied to landfill gas (LFG) projects. The authors assessed transparency and accountability, which the authors determined as fundamental to GHG mitigation and climate education. The authors expanded on five innovative cases from our subset to illustrate pathways to improve equity and circularity in waste flows.FindingsUS higher education institutions (HEIs) can measure and educate more transparently about waste streams. While institutions using LFG offsets range in size, curriculum and geography, there were few methane capture projects supplying energy directly to campuses. Although HEIs generally rely on third-party providers for waste management, cases demonstrate how universities can play a role in methane use, and be incubators for climate action and related employment.Practical implicationsIllustrative cases demonstrate the educational and institutional benefits from methane use.Social implicationsHEIs can generate pathways of a “just” transition to a fossil-free circular economy.Originality/valueTo the best of the authors’ knowledge, this is one of the first comparative studies examining waste sector methane capture and the potential for high-impact educational practices and sustainability training in US HEIs.

Development of a finer-resolution multi-year emission inventory for open biomass burning in Heilongjiang Province, China

Open biomass burning (OBB) is a significant source of air pollutants, profoundly impacting regional air quality and global climate change. However, due to the lack of high-resolution burned area products, limited biomass data resolution, and inappropriate emission factors (EFs), current OBB emission inventories have significant uncertainties. In this study, we integrated the FireCCI51 burned area product (250 m), high-resolution gridded biomass data, localized EFs, and various statistical survey data to compile a finer-resolution (250 m) and long-term (2001–2020) inventory of 11 pollutants for Heilongjiang Province (an important agricultural and forestry region in China). The results indicated that the annual average OBB emissions in Heilongjiang Province were 12.26, 63.70, 931.60, 17,203.35, 16.09, 171.25, 39.83, 71.22, 184.33, 129.16, and 6.35 Gg for BC, CH4, CO, CO2, NH3, NMVOC, NOx, OC, PM10, PM2.5, and SO2, respectively. Taking PM2.5 as an example, emissions from cropland, forest, and grassland burning accounted for 73%, 26%, and 1% respectively. Geographically, emissions were primarily concentrated in the western, southwestern, and northeastern regions of Heilongjiang. The peak PM2.5 emissions exhibited notable seasonal variation, with maxima occurring in April and October. This is primarily due to the extensive burning of straw during the spring and autumn ploughing seasons. The results of this study provide a detailed multi-year inventory crucial for atmospheric transport models and can support the development of effective pollution control strategies and greenhouse gas mitigation measures.

Influence of nano-encapsulated Yucca schidigera extract on ruminal anaerobic gases of methane, carbon monoxide, and hydrogen sulfide production of different carbohydrate-based diets

Saponins, the primary component of Yucca schidigera extract (YSE), are known to influence microbial activity in the rumen, which can affect various fermentation parameters. Moreover, encapsulating YSE with Chitosan (CS) at varying carbohydrate levels (CHO) adds another layer of complexity that can provide valuable insights into the use of additives in mitigating greenhouse gases. This study investigated the impact of both crude and encapsulated forms of YSE on the production of ruminal anaerobic gases in cattle fed different levels of CHO-based diets. Ruminal contents were obtained from four slaughtered, crossbreed bulls (Charollais × Limousin) with a live weight of 400 ± 25 kg. The experimental design followed a completely randomized factorial arrangement, with factors including CHO level (25%, 45%, and 55% DM), YSE forms (without extract, CS, crude, and nano-capsules), and dose of extract (0, 0.25, 0.5 and 1.0 mL/g of DM). Results showed that the type of extract significantly affected asymptotic total gas production, methane (CH4), Hydrogen sulfide (H2S), Carbon monoxide (CO), and dry matter digestibility. Nano-chitosan increased gas production and exhibited greater efficiency in reducing CH4 production by up to 61.36%. While crude YSE reduced CH4 production by 38%, nano-capsules increased production by 17.7% to 42.8%. Furthermore, a significant interaction effect among CHO levels, type of extract, and extract dose was observed, particularly impacting H2S and CH4 production after 48 hours of incubation, alongside an increase of about 25.3% in metabolizable energy compared to the control. The use of CS and YSE significantly (p <0.0001) improved the CH4 conversion efficiency by 71.3% and 23.4% respectively, and at some point, the encapsulation of YSE resulted in a significant reduction in efficiency by up to about 49.5%. The study concluded that both CS and YSE have the potential to enhance digestibility in cattle and reduce CH4 production and its conversion efficiency. However, encapsulating YSE with CS may reduce the efficiency of either compound in optimizing ruminal fermentation, unless other influencing factors are carefully considered. Therefore, the optimal efficacy of nano-encapsulated YSE depends on finding a balance between extract type, dosage, and dietary CHO level.

Evaluation of Ports in Terms of Greenhouse Gas Emissions and Energy: A Case Study

This study considers green port-based strategies that improve environmental performance in the context of urban areas and promote sustainable solutions to combat climate change. As an important component of the city, ports have a significant impact on socioeconomic development. In fact, given that ports in Turkey operate in limited spaces and city centers, pollution from port operations has a direct impact on both urban life and port workers. In recent years, the green port approach has become increasingly important within the scope of climate change adaptation programs. Particularly in Turkey, a large number of the ports are situated in the center of the city, which is bad for both the environment and community life. Although the Green Port Project in Turkey is currently voluntary, it will become a mandatory initiative in the coming periods due to Turkey's participation in the Paris Climate Agreement. In this study, the efforts to make Samsun Port, one of the important ports of Turkey, a green port are discussed. Studies on greenhouse gas emissions and mitigation measures, renewable energy approaches and their impacts are mentioned. In addition, this study includes the evaluation of integrated management systems, adoption of renewable energy, sustainable waste management, and greenhouse gas emission calculations as important components of a large-capacity port in the Black Sea to contribute to regional development.

Greenhouse gas emissions and mitigation strategies in China's municipal solid waste sector under the impact of the COVID-19 pandemic

With the continuous increase in municipal solid waste (MSW) generation, greenhouse gas (GHG) emissions caused by MSW treatment have gradually become an important environmental concern. This study developed a comprehensive ten-factor analysis framework using the generalized Divisia index method (GDIM) to decompose the driving factors of GHG emissions from MSW sectors in China and its 31 provinces from 2010 to 2022, including population, economy, consumption, and waste generation. The heterogeneity of factor contributions was discussed from both temporal and spatial perspectives to propose mitigation strategies for provincial MSW sectors. The results indicated the following: (1) GHG emissions from the MSW sector increased from 2010 to 2019, followed by a 20.7% decrease from 2019 to 2022 due to the COVID-19 pandemic. Regionally, emissions were greater in the eastern provinces than in the central and western provinces. (2) The main positive contributors to the increase in GHG emissions were the consumption expenditure of urban households (HCE, 27.61 MtCO2e) and GDP (25.71 MtCO2e). GHG emissions per HCE (-27.31 MtCO2e) and GHG emissions per GDP (-25.45 MtCO2e) were the main factors for emission reduction. (3) The contributions of ten driving factors to each province varied significantly across different periods, with the negative effect of emission reduction factors increasing under the impact of the pandemic. The findings of this study can support policymakers in developing differentiated mitigation strategies at the provincial level to promote the sustainable transformation of waste management in China.

Effect of acids produced by the dissolution of sulfur and nitrogen oxides in the performance of MEA solvent in CO2 capture: Experimental results and modeling

Solvent-based CO2 capture is very important for the mitigation of greenhouse gases. The presence of SO2 and NO2 is observed in several types of CO2-containing industrial flue gases and even small concentrations can cause significant changes in the performance of the solvent. Their effects on the CO2 solubility have received very little attention. To simulate the effect of dissolution and accumulation of SO2 and NO2 acid gases on the CO2 loading of aqueous ethanolamine (MEA) solutions, H2SO4 and HNO3 were added, as sources of NO3− and SO4−2 anions, respectively. The CO2 solubility in 30% wt. aqueous MEA solutions containing 2.9% wt. H2SO4 with and without 1.8% wt. HNO3 was experimentally measured using a pressure decay method at 313, 333 and 353 K and approximately 5-500 kPa. In both cases, it is revealed that the addition of H2SO4 and HNO3 substantially decreases the CO2 solubility. In addition, the modified Kent-Eisenberg model was used to predict the CO2 solubility in all systems and at all the studied conditions. The model predictions are in satisfactory agreement with the experimental data presenting Average Absolute Deviations between 4.8 and 6.8 % in all cases.

Scaling down recombinant carbonic anhydrase isolation with immobilized metal ion chromatography (IMAC): Harnessing enzymatic carbon dioxide capture and mineralization

BackgroundHuman activities have led to increased atmospheric CO2 levels, raising concerns about climate change. Carbonic anhydrase (CA) enzymes show promise for transforming CO2 into valuable products like calcium carbonate (CaCO3) through mineralization. Purifying and immobilizing CA enzymes on nanofiber membranes enhances their catalytic activity, enabling efficient CO2 conversion and mineralization. MethodsRecombinant CA was purified using immobilized metal affinity chromatography (IMAC), optimizing pH, biomass concentration, flow rate, and loading volume for maximum efficiency. The CA enzyme was then immobilized onto a weak ion exchange nanofiber membrane functionalized with AEA-COOH to create the CA-modified membrane (AEA-COOH-CA), enhancing CO2 conversion and CaCO3 mineralization. Significant findingsOptimal purification conditions (pH 7, 1 % biomass, 0.1 mL/min flow rate, 1.0 mL loading volume) were determined using IMAC. The CA-modified membrane effectively converted CO2 and mineralized CaCO3, demonstrating the potential for environmental CO2 sequestration. The immobilized CA activities of the AEA-COOH-CA nanofiber membranes exhibited 473.42 WAU/g-membrane, corresponding to 7.10 WAU per membrane piece. The CaCO3 precipitation reached 83.90 mg, with a precipitation efficiency of 11.82 mg CaCO3/WAU. These findings underscore the promise of enzymatic carbon capture using CA-modified membranes, offering a sustainable solution for greenhouse gas mitigation.

Conversion of Spirulina platensis into Methanol via Gasification: Process Simulation Modeling and Economic Evaluation

The conversion of bioresources like Spirulina platensis (SP) into value-added chemicals, such as methanol, offers a sustainable replacement of fossil fuels and contributes to greenhouse gas mitigation. This study presents an integrated process simulation model, developed using Aspen Plus v10®, for the steam gasification of SP and subsequent methanol production. Process parameters, including temperature range from 650-950°C, steam/feed ratio from 0.5-2, and recycle ratio from 0-9, were investigated to optimize syngas composition and methanol yield. Results demonstrated that increasing temperature enhances H2 and CO production while reducing CO2 and CH4, significantly increasing methanol production from 6500 to 9500 kg/h. The steam/feed ratio also influences syngas composition and methanol yield, with higher ratios promoting H2 and CO2 production and reducing CO and CH4. The economic evaluation of two scenarios, a base case and an optimum case, shows that the capital expenditure (Capex) and operating expenditure (Opex) are 19.3M$ and 9.07M$ for the base case, and 20.018M$ and 10.21M$ for the optimum case. The analysis also reveals that the optimum case, with higher methanol production (7.2 tonnes/h compared to 6.7 tonnes/h in the base case), generates a higher net income (9.76 M$/y) and reduces CO2 emissions (4.918 tonnes CO2-e/y compared to 5.72 tonnes CO2-e/y). The energy flow indicates the input energy requirement, the energy carried by methanol, and the surplus energy, totalling 26740 kW to meet the major system's energy demands. This study provides valuable insights for researchers, policymakers, and commercial entities seeking to develop sustainable and economically viable biofuel production processes.