Negative Carbon Emissions Research Articles

Exploring pathway to achieving carbon neutrality in China under uncertainty

China has announced its long-term goal of achieving carbon-neutrality before 2060, and it is necessary to identify the main driving forces of carbon emission, so that future carbon emission can be projected and effective measures to reduce carbon emission can be identified under uncertainty. Using a structural decomposition analysis model, China’s CO2 emission change within the period 2002–2017 were decomposed into the changes of six factors, classified as efficiency effect, structure effect and scale effect, and the key driving forces of CO2 emission are identified. By aggregating the driving forces, the future CO2 emissions are projected and the potential contribution of each driving force to reaching carbon–neutral is examined under uncertainty. The results show that in the period 2002–2017, economic growth increased CO2 emission by 11.4 billion tons as the largest driver of CO2 emission growth, while energy efficiency improvement contributed most to reducing CO2 emission by 3.38 billion tons. The projection analysis shows that multiple carbon reduction policies are needed simultaneously for China to achieve carbon neutrality, and accelerating the energy efficiency improvement and energy mix transformation plays key role. Moreover, negative carbon emission technologies is still necessary, which needs to contribute to reducing CO2 emission by at least 1.82 billion tons.

Progress in lignocellulosic biomass valorization for biofuels and value‐added chemical production in the EU: A focus on thermochemical conversion processes

AbstractThe demand for sustainable energy sources has increased owing to environmental concerns, such as climate change, rising energy demand and rapid industrialization. Biomass utilization for bioenergy and value‐added chemical production has become essential for creating a circular low‐carbon bioeconomy and sustainable waste management techniques. This review focuses on thermochemical processes and analyzes the trends of biomass utilization for energy production in the EU over the last decade. It discusses the current state‐of‐the‐art of gasification, pyrolysis, advanced combustion and liquefaction technologies, and presents the individual challenges and prospects of each process. A comprehensive overview of previous studies related to each conversion technology is provided to pave the way for future thermochemical, biochemical and integrated biomass valorization studies. Additionally, the review discusses biomass thermochemical conversion processes, which are combined with carbon capture, such as gasification, liquefaction and pyrolysis. These processes offer the potential to achieve negative net atmospheric carbon emissions, which can contribute to global warming mitigation efforts.

Dual‐Role of Polyelectrolyte‐Tethered Benzimidazolium Cation in Promoting CO2/Pure Water Co‐Electrolysis to Ethylene

AbstractElectrochemical CO2 reduction reaction (CO2RR), as a promising route to realize negative carbon emissions, is known to be strongly affected by electrolyte cations (i.e., cation effect). In contrast to the widely‐studied alkali cations in liquid electrolytes, the effect of organic cations grafted on alkaline polyelectrolytes (APE) remains unexplored, although APE has already become an essential component of CO2 electrolyzers. Herein, by studying the organic cation effect on CO2RR, we find that benzimidazolium cation (Beim+) significantly outperforms other commonly‐used nitrogenous cations (R4N+) in promoting C2+ (mainly C2H4) production over copper electrode. Cyclic voltammetry and in situ spectroscopy studies reveal that the Beim+ can synergistically boost the CO2 to *CO conversion and reduce the proton supply at the electrocatalytic interface, thus facilitating the *CO dimerization toward C2+ formation. By utilizing the homemade APE ionomer, we further realize efficient C2H4 production at an industrial‐scale current density of 331 mA cm−2 from CO2/pure water co‐electrolysis, thanks to the dual‐role of Beim+ in synergistic catalysis and ionic conduction. This study provides a new avenue to boost CO2RR through the structural design of polyelectrolytes.

Dual-Role of Polyelectrolyte-Tethered Benzimidazolium Cation in Promoting CO2/Pure Water Co-Electrolysis to Ethylene.

Electrochemical CO2 reduction reaction (CO2RR), as a promising route to realize negative carbon emissions, is known to be strongly affected by electrolyte cations (i.e., cation effect). In contrast to the widely-studied alkali cations in liquid electrolytes, the effect of organic cations grafted on alkaline polyelectrolytes (APE) remains unexplored, although APE has already become an essential component of CO2 electrolyzers. Herein, by studying the organic cation effect on CO2RR, we find that benzimidazolium cation (Beim+) significantly outperforms other commonly-used nitrogenous cations (R4N+) in promoting C2+(mainly C2H4) production over copper electrode. Cyclic voltammetry and in-situ spectroscopy studies reveal that the Beim+ can synergistically boost the CO2 to *CO conversion and reduce the proton supply at the electrocatalytic interface, thus facilitating the *CO dimerization toward C2+formation. By utilizing the homemade APE ionomer, we further realize efficient C2H4 production at an industrial-scale current density of 331 mA cm-2 from CO2/pure water co-electrolysis, thanks to the dual-role of Beim+ in synergistic catalysis and ionic conduction. This study provides a new avenue to boost CO2RR through the structural design of polyelectrolytes.

Study on thermal properties of bio-char prepared by photo-thermal pyrolysis

Photo-thermal pyrolysis provides a new method for the preparation of bio-char through the energy absorption of the intermittent solar energy into the carbon materials to achieve the energy storage and negative carbon emissions. The evolution of thermal properties of different chars prepared by photo-thermal pyrolysis with different final-reaction temperatures and heating rates was studied. The study of specific heat capacity showed that the final-reaction temperature had a stronger impact than the heating rate. At a final-reaction temperature of 800 °C, the maximum specific heat capacity of rice straw and pine char reached 1595 J·kg−1·K−1 and 2070 J·kg−1·K−1 respectively. Measurements of thermal conductivity showed that the higher final-reaction temperature and the higher heating rate both increased the thermal conductivity of char. Rice straw char had a maximum value of 0.2203 W·m−1·K−1 at 800 °C and 500 °C/min, which was almost twice the thermal conductivity of char at 400 °C and 50 °C/min. Further correlation analysis showed the physical structure of the char, especially its density and pore size, had a greater impact on thermal conductivity. The multiple linear model of thermal conductivity was established, which not only had a good fitting effect but also well predicted the thermal conductivity of another kind of char, and the error was within 10%. This study demonstrates the potential of photo-thermal pyrolysis char as a heat carrier and light absorption medium during photo-thermal pyrolysis.

Rigorous simulation and comprehensive analysis for the novel glycerol carbonate (GC) production process via indirect conversion of CO2

Aiming to achieve net-zero and negative carbon emissions, an innovative process that converts CO2 into glycerol carbonate (GC) through an indirect pathway was rigorously investigated for the first time. The study began with a thorough consideration of the thermodynamic properties and reaction kinetics. Subsequently, alternative processes varying in reactor configurations were proposed. Fuzzy optimization was performed on the proposed processes to consider the competing objectives of minimizing production costs and reducing CO2 emissions. With thorough analysis, we have concluded that the process employing two reactors in a cascade (the “2R-process”) is the most attractive. This process shows promise in both economic and decarbonization aspects. Under a targeted internal rate of return (IRR) of 15%, the minimum required selling price (MRSP) for GC is 0.628 USD/kg. Additionally, the entire process fixes 0.238 kg of CO2 per kg of GC produced (CO2-e = −0.238). These indices are superior to those of the previously proposed process based on reactive distillation (MRSP = 1.328 USD/kg, CO2-e = +0.209), and to many cost data for GC available in the literature (2.4 to 6.0 USD/kg). Finally, a control structure was established for the proposed process to manage the specified feed disturbances in flowrate and composition, without the need for any composition measurements. The control strategy involves the use of selective temperature control for the reactor, and two temperature difference controllers for the extractive distillation column (i.e. control scheme 2). In summary, the proposed process reveals significant potential to serve as an essential component in a future decarbonized economy.

Low-carbon optimal dispatch of integrated energy system considering the operation of oxy-fuel combustion coupled with power-to-gas and hydrogen-doped gas equipment

To reduce carbon emissions and optimize energy utilization of integrated energy system (IES), an integrated electricity-heat-gas energy system containing coupled operation of oxy-fuel combustion capture and power to gas (OCC–P2G) and hydrogen-doped gas equipment is established in this paper. Firstly, the introduction of OCC technology transforms the thermal power unit into the OCC unit. The net output model of OCC unit and the equation of electric-carbon characteristic are established. Secondly, the two-stage refinement model of power to gas (P2G) and the model of hydrogen-doped gas equipment are constructed. Thirdly, considering the fairness principle of punishing positive carbon emissions and rewarding negative carbon emissions, a reward-penalty staircase carbon trading mechanism was constructed to constrain system carbon emissions. On this basis, an economic dispatch model of integrated energy system is established. The simulation results demonstrate that the ratio of wind abandonment is 0%, the actual carbon emission is only 35.08% of carbon quota, and the operation cost is only 237.1 thousand dollars. By setting multiple scenarios for comparative verification, the proposed strategy has lower economic cost and carbon emission.

Does negative interest rate policy impact carbon emissions? Evidence from a quasi-natural experiment

Financial policy is an essential tool for achieving sustainable economic development and has been extensively studied in the environmental economics literature. This study employs panel data of 45 countries from 2007 to 2019 and a multi-period difference-in-differences (DID) method to investigate the mechanism and transmission path of negative interest rate policy on carbon dioxide emissions. The results indicate that the implementation of negative interest rate policy can significantly reduce CO2 emissions, and various robustness tests substantiate this result. Mechanism tests show that when the interest rate breaks the zero lower bound constraint, CO2 emissions can be reduced through the exchange rate channel, while the credit channel is blocked. Furthermore, the mitigation effect of negative interest rate policy varies with country heterogeneity, and countries with low comprehensive development, high economic growth, and high investment levels have more potential to control environmental degradation. The study evaluates the effects of negative interest rate policy from an environmental perspective, providing useful policy insights for monetary authorities to formulate effective policies to promote coordinated economic and environmental development.

Sludge-derived biochar: Physicochemical characteristics for environmental remediation

The global production of fecal wastes is envisioned to reach a very high tonnage by 2030. Perilous handling and consequential exposition of human and animal fecal matter are inextricably linked with stunted growth, enteric diseases, inadequate cognitive skills, and zoonoses. Sludge treatment from sewage and water treatment processes accounts for a very high proportion of overall operational expenditure. Straightforward carbonization of sludges to generate biochar adsorbents or catalysts fosters a circular economy, curtailing sludge processing outlay. Biochars, carbonaceous substances synthesized via the thermochemical transformation of biomass, possess very high porosity, cation exchange capacity, specific surface area, and active functional sorption sites making them very effective as multifaceted adsorbents, promoting a negative carbon emission technology. By customizing the processing parameters and biomass feedstock, engineered biochars possess discrete physicochemical characteristics that engender greater efficaciousness for adsorbing various contaminants. This review provides explicit insight into the characteristics, environmental impact considerations, and SWOT analysis of different sludges (drinking water, fecal, and raw sewage sludge) and the contemporary biochar production, modification, characterization techniques, and physicochemical characteristics, factors influencing the properties of biochars derived from the aforestated sludges, along with the designing of chemical reactors involved in biochar production. This paper also manifests a state-of-the-art discussion of the utilization of sludge-derived biochars for the eviction of toxic metal ions, organic compounds, microplastics, toxic gases, vermicomposting approaches, and soil amelioration with an emphasis on biochar recyclability, reutilization, and toxicity. The practicability of scaling up biochar generation with multifaceted, application-accustomed functionalities should be explored to aggrandize socio-economic merits.

Anammox bacteria adapt to long-term light irradiation in photogranules.

Photogranules composed of algae, nitrifiers, and anammox bacteria are promising for nitrogen removal from wastewater with reduced aeration and carbon emissions. However, it is difficult to be achieved as the potential inhibition of anammox bacteria by light. In this study, a syntrophic algal-partial nitrification/anammox granular sludge process was developed, with a nitrogen removal rate of 294.5mg N/(L·d). We found the symbiosis in the community promoted the adaptation of anammox bacteria under light, and cross-feeding played an important role. Microalgae in the outer layers of photogranules sheltered most of the light and supplied cofactors and amino acids to promote nitrogen removal. In particular, Myxococcota MYX1 degraded the extracellular proteins produced by microalgae, providing amino acids to the entire bacterial community, which helped anammox bacteria save metabolic energy and adapt to light. Notably, the anammox bacteria Candidatus Brocadia exhibited unique light-sensing potential and adaptations to light irradiation compared with Candidatus Jettenia, including diverse DNA repair, scavenging of reactive oxygen species, cell movement. The phytochrome-like proteins encoded by Candidatus Brocadia further facilitated their spatial positioning and niche partitioning in photogranules. This study provides insights into the response of anammox bacteria in the algae-bacteria symbiosis system and suggests its potential application for carbon-negative nitrogen removal.

Moisture-driven CO2 pump for direct air capture

Direct Air Capture, the chemical separation of carbon dioxide (CO2) from air, is considered a necessary approach to generate negative carbon emissions and in turn limit global warming, though energetic and monetary costs must continue to decline to meet the needed gigaton scale. The promise of energy-efficient and continuous carbon dioxide membrane separation has only recently been investigated with the development of facilitated chemical transport and novel electrochemically driven methods. This work demonstrates the potential for continuous pumping of CO2 from air using commercial anion exchange membranes driven solely by a water vapor gradient. A reactive transport model that couples ionic transport with moisture sensitive bicarbonate chemistry in charged polymers, also termed moisture swing sorption, was developed alongside experimentally measured equilibrium and transport properties of CO2 and water vapor in Fumasep FAA-3 to determine the mass transport limits of such a system. The results show that the commercial membrane is kinetically limited by the moisture sensitive chemistry, enabling a CO2 current of 1.1 μmol/m2∙ s. In diffusion limited materials, a CO2 pumping flux can reach 11 μmol/m2∙ s in and peak performance is expected with a dry air relative humidity around 50% pumping into a saturated water vapor permeate. In all configurations, water loss becomes the major cost in such a separation and must be managed through optimal polymer design or water recovery mechanisms. The work demonstrates the applicability of a new driving force, the evaporation of water, to meet the energetic demand of CO2 separation from air.

Life cycle assessment of microalgal cultivation medium: biomass, glycerol, and beta-carotene production by Dunaliella salina and Dunaliella tertiolecta

Abstract Purpose Dunaliella is a halophilic genus of microalgae with high potential in the global food market. The microalgal cultivation process contributes to not only economic impact but also environmental impact, especially regarding the artificial medium composition. In this context, a life cycle assessment was carried out to analyze the impacts associated with the components of the modified Johnson medium (MJM) and to predict the best scenarios to cultivate Dunaliella tertiolecta and Dunaliella salina for biomass, glycerol, and beta-carotene production. Method Two chains were analyzed separately: (1) Dunaliella salina (strain DF 15) cultivated in 8 scenarios combining different nitrogen (0.1 and 1.0 g L−1 KNO3) and magnesium (1.1–2.3 g L−1 MgCl2.6H2O) concentrations to produce biomass, glycerol, and beta-carotene and (2) Dunaliella tertiolecta (strain CCAP 19/30) cultivated in 5 scenarios combining different nitrogen (0.1 and 1.0 g L−1 KNO3) and salt (116.9–175.4 g L−1 sea salt) concentrations to produce biomass and glycerol. In addition, we evaluated the potential of cultivating these species to reduce the carbon footprint of the proposed scenarios. Results and discussion For D. salina, S5 (1 g L−1 KNO3, 1.1 g L−1 MgCl2.6H2O) had the lowest environmental damage for biomass (74.2 mPt) and glycerol production (0.95 Pt) and S3 (0.1 g L−1 KNO3, 1.9 g L−1 MgCl2.6H2O) for beta-carotene (3.88 Pt). T4 (1 g L−1 KNO3, 116.9 g L−1 sea salt) was the best for D. tertiolecta for biomass (74 mPt) and glycerol (0.49 Pt). “Respiratory inorganics,” “Non-renewable energy,” and “Global warming” were the most impacted categories. “Human health,” “Climate change,” and “Resources” had the highest share of all damage categories. All the scenarios presented negative carbon emission after proposing using brine as alternative salt source: S5 was the best scenario (− 157.5 kg CO2-eq) for D. salina and T4 for D. tertiolecta (− 213.6 kg CO2-eq). Conclusion The LCA proved its importance in accurately predicting the optimal scenarios for MJM composition in the analyzed bioproducts, as confirmed by the Monte Carlo simulation. Although the absolute values of impacts and productivity cannot be directly compared to large-scale cultivation, the validity of the LCA results at this scale remains intact. Productivity gains could outweigh the impacts of “surplus” MJM components. Our study showcased the potential of combining D. salina and D. tertiolecta cultivation with CO2 capture, leading to a more environmentally friendly cultivation system with a reduced carbon footprint.

Removal of Formaldehyde and Its Analogues Using a Hybrid Assembly of Pyrene-Modified Hydrazide and rGO: A Negative Carbon Emission and Green Chemical Decomposition Method.

Indoor gaseous formaldehyde is the main environmental pollutant that can cause fatal threats to human health. A number of physical and chemical methods have been developed to tackle this issue. However, the existing methods are still unsatisfactory to meet the requirement of sustainable development owing to the flaws of low efficiency and reversible or second pollution. Herein, a chemical method based on a nucleophilic reaction between hydrazine and aldehyde that generates the only by-product of H2O is designed for the removal of formaldehyde. 1-Pyrenebutyric hydrazide was synthesized by a simple esterification reaction and then self-assembled on reduced graphene oxide (rGO) with a large surface area by forming π-π stacking to obtain a composite for chemical removal of gaseous formaldehyde under ambient conditions. In a practical test, the formaldehyde removal rate could reach 91% of the theoretical value, which meets the requirement for commercial formaldehyde removal applications. After 10 times recycling, the formaldehyde removal rate still remains as high as 85%. Moreover, the composite could be regenerated in weak acidic media, which greatly reduce the manufacturing cost in practical applications.

Methodology for estimating the decarbonization potential at the neighborhood level in an urban area: Application to La Carrasca in Valencia city - Spain

Decarbonization potential estimation is critical to calculate and measure a specific area's actual greenhouse gas reduction capacity. However, it is often challenging to estimate decarbonization potential, especially when dealing with large and diverse urban areas. Therefore, it is necessary to study the carbon footprint in the study area before evaluating decarbonization potential. This study aimed to develop a methodology for estimating the decarbonization potential in a district and applying it to La Carrasca neighborhood in Valencia City, Spain. The concept behind selecting a smaller area encompassing multiple sectors, including residential and services, rather than an entire city was to concentrate on often overlooked details, streamline the information processing, and consider factors that are otherwise unfeasible when a larger area is chosen. The proposed method considers all potential emissions according to scopes 1, 2, and 3 (direct emissions, primary indirect emissions, and other indirect emissions, respectively) and all possible decarbonization measures, including renewables, nature-based solutions, electrification, and improved waste management. The study utilizes several tools to achieve these objectives, including HOMER, QGIS, DATADIS, Google Earth, and Excel. The results of this study showed that the decarbonization potential of La Carrasca neighborhood is 7488 tons of CO2, representing a bit more than 11% of its overall emissions, and the total cost per emission saving during the lifetime of all the analyzed technologies is 200 €/tCO2. However, achieving complete decarbonization of the area would require more aggressive mitigation measures, government incentives, policy changes, new measures, and changes in habits among the population. Overall, the numerical results demonstrate the importance of considering an area's carbon footprint and utilizing a comprehensive methodology to estimate the decarbonization potential for effective greenhouse gas reduction. The proposed methodology could be extrapolated to other areas to estimate decarbonization potential and emissions and to determine the feasibility of achieving negative carbon emissions.

Development of high capacity moisture-swing DAC sorbent for direct air capture of CO2

Direct air capture (DAC) of CO2 complements traditional carbon capture technologies to achieve zero- or negative-carbon emissions. One of the most promising DAC technologies is moisture-swing adsorption due to its low regeneration costs and easiness of operation, particularly when using amine-based anion-exchange resins (AER) as sorbents, but the limited CO2 sorption capacity and desorption efficiency of current AERs are still critical challenges hindering the large-scale implementation of DAC. For the first time, this work developed a novel diamine-based double quaternary ammonium anion-exchange resins (Diamine-DQ-AER) by modifying commercial resins with tertiary diamines. The significantly improved quaternary ammonium content in Diamine-DQ-AER (68–81 %) compared to diamine-based single quaternary ammonium anion-exchange resins (Diamine-SQ-AER) resulted in an unprecedented moisture-swing DAC capacity of 3.41 mmol/g under DAC conditions, nearly doubled that of Diamine-SQ-AER. Diamine-DQ-AER also showed a stable capacity in the 6-cycle test, outperforming most moisture-swing DAC sorbents reported in the literature. Moreover, a complete desorption kinetic curve was obtained using an optimized testing protocol. It found that the CO2 adsorption/desorption process involves two stages, and the material exhibited fast desorption kinetics in the 1st stage.

Harnessing the Hybridization of a Metal-Organic Framework and Superbase-Derived Ionic Liquid for High-Performance Direct Air Capture of CO2.

Direct air capture (DAC) of CO2 has emerged as the most promising "negative carbon emission" technologies. Despite being state-of-the-art, sorbents deploying alkali hydroxides/amine solutions or amine-modified materials still suffer from unsolved high energy consumption and stability issues. In this work, composite sorbents are crafted by hybridizing a robust metal-organic framework (Ni-MOF) with superbase-derived ionic liquid (SIL), possessing well maintained crystallinity and chemical structures. The low-pressure (0.4mbar) volumetric CO2 capture assessment and a fixed-bed breakthrough examination with 400ppm CO2 gas flow reveal high-performance DAC of CO2 (CO2 uptake capacity of up to 0.58mmol g-1 at 298 K) and exceptional cycling stability. Operando spectroscopy analysis reveals the rapid (400ppm) CO2 capture kinetics and energy-efficient/fast CO2 releasing behaviors. The theoretical calculation and small-angle X-ray scattering demonstrate that the confinement effect of the MOF cavity enhances the interaction strength of reactive sites in SIL with CO2 , indicating great efficacy of the hybridization. The achievements in this study showcase the exceptional capabilities of SIL-derived sorbents in carbon capture from ambient air in terms of rapid carbon capture kinetics, facile CO2 releasing, and good cycling performance.

Spatial-temporal characteristics of carbon emissions corrected by socio-economic driving factors under land use changes in Sichuan Province, southwestern China

The spatial-temporal distribution characteristics of carbon emissions under land use changes can fully reflect the impact of socio-economic development caused by human activities on terrestrial ecosystems. However, previous studies just focused on the traditional carbon emission coefficient method which was applied to calculate carbon emission amounts from different land use types at a large spatial scale over a long-time period. This approach did not consider the effects of spatial heterogeneity of socio-economic factors on carbon emissions, which can lead to overestimating and underestimating carbon emissions in intra-study areas. Therefore, it is urgent to build a corrected method integrating socio-economic factors into carbon emission calculation which can make up for this shortcoming. Firstly, this study calculated the carbon emissions under land use changes through the traditional method based on spatial maps of land uses and fossil energy consumption during 2000–2018 in 21 cities (states) in Sichuan Province. From 2000 to 2018, the overall carbon emissions increased by 43.14%, and the high and low carbon emission values occurred in the east and west of the study site, respectively. Chengdu had the largest carbon emissions, and its maximum value appeared in 2015. Only the Tibetan Autonomous Prefecture of Garz (Garz) had a negative carbon emission value. Furthermore, the total carbon emissions were significantly correlated with Gross Domestic Product (GDP) and population. This study then proposed a method to correct carbon emissions by considering the spatial heterogeneity of GDP and population. There were some obvious differences between uncorrected and corrected carbon emissions. From 2000 to 2018, the corrected carbon emissions also showed an increasing trend, but their values were much higher than uncorrected carbon emissions. The city (state) with the largest corrected carbon emissions was still in Chengdu but the maximum value occurred in 2018. The city (state) with negative corrected carbon emissions was still in Garz, but its corrected values were much lower than uncorrected carbon emissions. Additionally, the center of gravity of positive carbon emissions shifted from Ziyang before the correction to Chengdu after the correction during 2000–2018. In summary, the corrected carbon emissions proposed in this study by considering socio-economic driving factors can reflect an actual condition of carbon emissions from land use. The results can offer a scientific basis for the local government to construct low-carbon land use patterns in Sichuan Province. This approach can be promoted to calculate carbon emissions in other study sites at different spatial scales.

Energy and exergy analyses of biomass IGCC power plant using calcium looping gasification with in situ CO2 capture and negative carbon emission

Energy and exergy analyses of biomass IGCC power plant using calcium looping gasification with in situ CO2 capture and negative carbon emission

Evaluation of the relationship of wastewater treatment and biodiesel production by microalgae cultivated in the photobioreactor

Microalgae has a great preponderance of fast growth rate and high oil contents. Mixed wastewater and industrial waste gas are utilized in this study as the microalgae's growing medium and resource of inorganic carbon. A combined study of waste usage and biomass energy development is conducted based on closed photobioreactor cultivation. With a focus on the cost of microalgal biodiesel, the financial benefits of waste treatment, the CO2 absorption effect, and biodiesel yield, an assessment of the production process is conducted for different algae species under different energy supply situations. The experimental results indicate that Model algal species 3 (M3) are better adapted for the production of biodiesel with the situation of wind power. It has the algae generates 6800 L of algal liquid, 32.3 kg of microalgae, 42.27 kg of CO2 emission reduction, and 12.47 kg of biodiesel in the single production cycle. The production of microalgae biodiesel based on photobioreactors can produce negative carbon emissions in the setting of a wind energy supply, and the total yearly biodiesel production in the same proliferation scale is at least 112.89 times that of open culture ponds. It has realized the sufficient coupling between waste utilization and biomass energy development through the development of microalgae biodiesel based on photobioreactor culture. It reduces the cost of biodiesel development and maintains high economic efficiency of waste disposal while producing negative carbon emissions. New theoretical guidance is provided by the target's advancement of renewable energy, carbon sequestration, and emission reduction, which has substantial effects on reducing pollution and enhancing significant ecological and environmental effects.

Green hydrogen production from decarbonized biomass gasification: An integrated techno-economic and environmental analysis

Biomass gasification represents an effective and promising conversion technology to different energy carriers/chemicals. Biomass gasification with CO2 capture will give an energy conversion system with negative CO2 emissions. This work assesses the techno-economic and environmental implications of decarbonized green hydrogen generation using the biomass gasification. Several pre-combustion decarbonization technologies were evaluated: chemical and physical scrubbing (absorption), membrane, hybrid membrane - chemical scrubbing. All evaluated biomass gasification concepts have 300 MW hydrogen output (corresponding to 100,000 Nm3/h hydrogen with purity above 99.95% vol.) with 90% carbon capture rate. Different system engineering tools were employed for the integrated assessment. As an important novelty outcome of this work, the green hydrogen production from decarbonized biomass gasification has promising potential to deliver high energy conversion efficiency (in the range of 57–59%), lower energy and cost penalties for decarbonization (about 2.2–3.5 net points), negative carbon emissions (considering that the primary fuel - biomass - is of renewable source). Among various assessed decarbonization technologies, the membrane system shows better techno-economic performances than the gas-liquid absorption (e.g., reduced CAPEX and OPEX by 7% and 7–9% respectively, inferior hydrogen production cost by about 7% etc.).