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Addressing climate change demands, energy security and resilience has necessitated replacing conventional fossil-based fuels with zero and carbon-neutral fuels/energy carriers. The most immediate solution is the partial and progressive substitution of conventional fuels in transportation. The effects of partially substituting gasoline with ammonia/hydrogen (NH 3 /H 2) mixtures in a spark ignition (SI) engine are investigated in this paper. The utilization of NH 3 /H 2 mixtures is a promising avenue of research since they can be produced from on-board NH 3 reforming, utilising heat energy that is recovered from hot exhaust gases. Experimental results indicate that adding NH 3 /H 2 enabled stable engine operation at lean conditions (λ = 1.4), resulting in reduced carbon-based emissions due to the non-carbon nature of NH 3 /H 2. Utilising an integrated approach that combined a hemispherical flame geometry model with a thermodynamic model, has revealed that the introduction of NH 3 /H 2 significantly enhanced the combustion speed during the initial phase and further improved combustion efficiency. However, nitrogen-based emissions such as NO and NO 2 increased. This work also assessed the performance of a conventional three-way catalyst (TWC) and a double-function ammonia slip catalyst (ASC) in mitigating emissions. The TWC effectively controlled carbon-based emissions and NO under stoichiometric conditions but exhibited reduced efficiency under lean conditions, especially with NH 3 present. The ASC demonstrated high NH 3 conversion efficiency even at low temperatures, making it suitable for engine start-up and warm-up phases. Under steady-state conditions with artificially increased NH 3 /NO X ratios, a significant reduction in NOx emission was achieved with the ASC. However, high NH 3 /NO X ratios increased nitrous oxide (N 2 O) formation and NH 3 slip. • A combined NH 3 /H 2 combustion study was carried out with a prototype catalyst aftertreatment system. • NH 3 /H 2 blend in gasoline enables lean combustion but raises NO X emissions. • Combustion models show H 2 boosts initial phase burn rates. • TWC lacks N-based abatement capacity in terms of lean and NH 3 presence. • ASC efficiency increases with temperature but worsens with decreasing NH 3 /NO X ratio. [ABSTRACT FROM AUTHOR]

[Display omitted] Achieving net-zero CO 2 emissions is the current main focus of China's carbon neutrality goal. However, non-CO 2 greenhouse gases (GHGs) are more powerful climate forcers, making their emission reduction an opportunity to rapidly mitigate future warming. Here, we evaluate non-CO 2 mitigation potentials, costs and climate benefits in the context of China's carbon neutrality goals. The assessment is conducted by coupling the integrated assessment model GCAM with a climate emulator. The findings indicate that mitigation technologies can largely reduce fluorinated gas emissions from industrial sectors, but long-term non-CO 2 reductions of energy sector activities rely heavily on fuel switching. Furthermore, the cumulative costs of deploying non-CO 2 mitigation technologies are projected to be less than 10 % of the total costs of achieving carbon neutrality from 2020 to 2060. If non-CO 2 mitigation measures are included in the overall mitigation portfolio, the benefits of avoided warming would by far outweigh the total mitigation cost increase. Our results thus highlight that incorporating a wider suite of GHGs into climate change mitigation strategies can enhance the cost-effectiveness of mitigation efforts. [ABSTRACT FROM AUTHOR]

The current energy and environmental problems demand the replacement of fossil fuels with renewable fuels. Research shows that hydrogen-enriched CNG fuels enhance the thermal efficiency of diesel engines while reducing gaseous emissions. This experimental work investigates the performance and emissions parameters of a diesel engine in dual fuel mode with hydrogen-enriched Bio-CNG (HBCNG). It is performed on a single-cylinder, four-stroke common rail direct injection (CRDI) diesel engine at 1500 rpm and 3.5 kW. The outcomes of this experiment are compared to a neat diesel operation. It is observed that at low load with 30% gaseous fuel substitution (GFS), brake thermal efficiency decreases by 13.70% and 15.53% for hydrogen and BCNG-enriched diesel, respectively. Similarly, at medium load, with the gaseous mixture of 40% H 2 and 60% BCNG co-combusted with 60% diesel, the BTE improves by 15.83%. At high load, 40% gaseous fuel mixture (40% H 2 + 60% BCNG) combustion with diesel results in 21.25% enhanced BTE. Moreover, at the same load condition and GFS, emissions of HC increase by 41.59%, CO decreases by 30%, CO 2 decreases by 55.36%, and NO x decreases by 25.94%. • The experiment is performed on a common rail direct injection diesel engine. • Hydrogen and Bio-CNG enriched diesel are used as the fuel. • Hydrogen and Bio-CNG mixture proportion in diesel are varied between 0 and 40%. • The engine load is varied between 0 and 80%. • The performance and emission parameters enhanced for 40% gaseous fuel mixture. [ABSTRACT FROM AUTHOR]

As the backbone of the international seaborne trade, the pollution and emission from shipping are highly concerned by governments and international organizations as well. The International Maritime Organization has designated five emission control areas (ECAs) to limit sulfur oxides emissions of ships. Meanwhile, the European Union has included the shipping industry in the EU Emission Trading System since 2024 to control their carbon emissions. The strategies like switching fuel, installing scrubber or detour, are commonly used to comply with the ECA regulation, but they may increase carbon emissions and possibly incur extra carbon trading cost. In this case, the shipping company should investigate the influence of marine emission trading system (METS) on emission reduction strategies used under ECA regulation. Therefore, this paper focuses on this problem and formulates it as a mixed-integer nonlinear programming model. Several numerical experiments are conducted to show the applicability of the proposed model. The results show that ship's detour behavior is inevitable under the ECA regulation, which incurs more carbon emissions. When METS regulation is not considered, the optimal emission reduction strategy is installing scrubber. In contrast, when METS regulation is considered, the optimal choice may be installing scrubber or fuel switching depending on different sailing route, which indicates the effect of METS on ship emission reduction strategy. Moreover, the fleet deployment and sailing speed of scrubber installation strategy are affected by METS regulation, while the strategies of fuel switching and using LNG-powered ship are almost unaffected. This indicates that installing scrubber is more easily affected by emission control policies. • Jointly optimize the ship's energy strategy and scheduling under ECA regulation. • Investigate the effect of METS on optimal solutions under ECA regulation. • Shipping company should re-optimize his energy strategy and ship scheduling plan under both ECA and METS regulation. [ABSTRACT FROM AUTHOR]

The global need for petroleum and its dwindling availability throughout the world demand an alternative fuel. Hydrogen-enriched algal biodiesel (ABD) is a potential option against conventional fuels due to its availability and positive effects on performance and emissions. Azolla pinnata algae is a high-yield fuel with reduced adverse impacts on the environment, requiring 2–5 days to double its biomass. This research work involves post-experimentation modeling to assess the performance and emissions of a CRDI diesel engine using a hydrogen-enriched blended fuel of Azolla pinnata ABD. Response surface methodology has been applied to optimize the load, fuel blend, and hydrogen gas substitution for performance and emissions characteristics. The ABD and hydrogen gas are varied between 0 and 40% in the pilot fuel for loads between 0 and 80%. The model indicates that the optimized load, blend, and hydrogen fuel substitution for this research are, respectively, 80%, 40%, and 40%. At the above-mentioned optimized parameters, the optimized values of BTE, CO, CO 2 , HC, and NO x are found to be 30.90%, 19.99 g/kWh, 288.89 g/kWh, 0.21 g/kWh, and 1.57 g/kWh, respectively. Adequacy precision greater than 4 and a percentage error between predicted and experimental values less than 5% indicate the model's ability to predict performance and emissions characteristics eventually. [Display omitted] • The experiment is performed on a CRDI dual-fuel diesel engine. • Diesel and biodiesel (Azolla pinnata) blends enriched with H 2 are used as fuel. • Experimental data has been used for developing mathematical & RSM models. • BTE & emissions are optimized for 80% load, 40% blend, and 40% GFS experimentally. • With a percentage error of less than 5%, RSM validated the experimental results. [ABSTRACT FROM AUTHOR]

With a specific end goal to take care of the worldwide demand for energy, broad research is done to create alternative and cost-effective fuel. The fundamental goal of this examination is to investigate the performance, emissions and vibration characteristics of a single cylinder four stroke diesel engine, working in dual fuel mode with biodiesel of Karanja oil ((BKO) as a renewable fuel and hydrogen (H 2) as gaseous fuel on low (2%), intermediate between medium-high (53%) and high (69%) load conditions. Biodiesel of Karanja oil as 20% biodiesel and 80% diesel known as BKO20, while 30% biodiesel and 70% diesel known as BKO30. With 25% introduction of gaseous fuel (H 2) and biodiesel (10%–40%) along with diesel showed an increase in brake thermal efficiency (BTE), 85.23%, 10.62% and 19.4% respectively as compared to parent diesel fuel operation. As far as emission is concerned, oxides of nitrogen (NO x) decreased on higher load conditions with a variation of biodiesel (10%–50%) in comparison to low load condition. However, the formation of monoxide (CO), carbon dioxide (CO 2) and un-burnt hydrocarbon (HC) decreases along with BKO50 using 25% hydrogen fuel substitution at high (69%) load conditions. • H 2 (25%) along with Karanja oil (40%) substituted by 65% diesel fuel. • Brake thermal efficiency (85.23%) optimum with Karanja oil (10%) by H 2 (25%) fuel. • Emission, combustion and its performance formed superior features. • NO x formation decreased as biodiesel substitution increases up to 50%. [ABSTRACT FROM AUTHOR]

The measures needed to limit global warming pose a particular challenge to current fossil fuel exporters, who must not only decarbonise their local energy systems, but also compensate for the expected decline in fossil fuel revenues. One possibility is seen in the export of green hydrogen. Using Algeria as a case study, this paper analyses how different levels of ambition in hydrogen exports, energy efficiency and fuel switching affect the cost-optimal expansion of the power sector for a given overall emissions reduction path. Despite falling costs for photovoltaics and wind turbines, the results indicate that in countries with very low natural gas prices, such as Algeria, a fully renewable electricity system by 2050 is unlikely without appropriate policy measures. The expansion of renewable energy should therefore start early, given the high annual growth rates required, which will be reinforced by additional green hydrogen exports. In parallel, energy efficiency is a key factor as it directly mitigates CO2 emissions from fossil fuels and reduces domestic electricity demand, which could instead be used for hydrogen production. Integrating electrolysers into the power system could potentially help to reduce specific costs through load shifting. Overall, it seems advisable to analyse hydrogen exports together with local decarbonisation in order to better understand their interactions and to reduce emissions as efficiently as possible. These results and the methodology could be transferred to other countries that want to become green hydrogen exporters in the future and are therefore a useful addition for researchers and policy makers. • The required strong capacity expansion for PV and wind is challenging, but feasible. • "Energy efficiency first" benefits both the local energy transition and H2 exports. • Fully renewable power systems require a suitable political framework. • Higher hydrogen exports might help to reduce the specific power system cost. • Fossil capacity expansion must be stopped to avoid lock-ins and higher future costs. [ABSTRACT FROM AUTHOR]

To attain a net zero-carbon emissions energy system, the grid needs dispatchable and flexible power production capable of responding to wind and solar energy variability. Hydrogen-fired gas turbines could play a role in meeting this requirement in the electricity grid; however, research and development are needed to assess the impact of the fuel change on these systems. This study aims to determine the effect of fuel switching on the cycle performance of a typical aero-derivative gas turbine, ranging from 25-35MW when combined with various steam-based bottoming cycles using Aspen Plus thermodynamic simulations. The gas turbine cycle's efficiency and net output power increased by about 2.26% and 5.24%, respectively, when fueled with hydrogen for the constant TIT control strategy compared with the base case. The other two control strategies—constant TOT and heat input—are also positive. The performance of the combined heat and power configurations, expressed by the fuel charged to power, is better for almost all the hydrogen-fired cases compared with the methane case. This implies that using hydrogen as fuel in the gas turbine and duct-firing requires less fuel to produce heat and electricity. Although hydrogen integration into the overall system may pose challenges with auxiliary equipment, storage, supply, and combustion, hydrogen as fuel shows promise in improving the performance of gas turbine combined heat and power units. • Hydrogen for GTs will be an enabler of low-carbon and flexible power production. • Switching to hydrogen enhances power and heat production in all operating strategies. • The GT performance improves with the hydrogen fraction for all operating strategies. • Hydrogen firing increases the operational flexibility of GT-based CHP configurations. [ABSTRACT FROM AUTHOR]

Alternative fuels of low or zero carbon content can decarbonise the shipping operations. This study aims at assessing the lifetime environmental-economic sustainability of ammonia and hydrogen, as alternatives to diesel fuel for short sea shipping cargo vessels. A model is employed to calculate key performance indicators representing the lifetime financial sustainability and environmental footprint of the case ship using a realistic operating profile and considering several scenarios with different diesel substitution rates. Scenarios meeting the carbon emissions reduction targets set by the International Maritime Organisation (IMO) for 2030 are identified, whereas policy measures for their implementation including the emissions taxation are discussed. The derived results demonstrate that the future implementation of carbon emissions taxation in the ranges of 136–965 €/t for hydrogen and 356–2647 €/t for ammonia can support these fuels financial sustainability in shipping. This study provides insights for adopting zero-carbon fuels, and as such impacts the de-risking of shipping decarbonisation. [Display omitted] • Economic and environmental sustainability assessment of diesel fuel substitution. • Scenarios for addressing IMO decarbonisation targets with ammonia and hydrogen. • Hydrogen fuel prices below 700 €/t provide economic sustainability. • Carbon tax of 136 €/t for H 2 and 261 €/t for NH 3 is required to reach baseline NPV. • H 2 substitution scenarios over performs ammonia in economic sustainability. [ABSTRACT FROM AUTHOR]

In order to comply with the latest Emission Control Areas (ECAs) regulations, ships must use expensive low-sulphur fuel oil or relatively cheap high-sulphur fuel oil (HFO) with desulphurization equipment. This study investigates the choice of green fuel and green technology for a coastal container ship with endogenous decision of sailing pattern. The sufficient and necessary conditions for a ship to adopt scrubber installation (SI) strategy are derived, which is dependent on factors including the equivalent sailing distance, the fuel price ratio, and scrubber parameters. The case study based on the China's coastal area is conducted. Numerical examples show that the introduction of scrubber technology on coastal vessels will reduce their evasion behavior. However, the increased sulphur reduction efficiency of scrubbers increases the evasion strategies of ships, which will increase the total emissions in coastal areas. The numerical example shows that introduction the scrubber technology to the coastal ships will reduce their evasion behavior. However, the scrubber investment will increase ships' sailing speed, increasing emissions within ECA. Therefore, governments can subsidize high abatement efficiencies of the scrubber to reduce actual ship emissions. • Investigate the choice of technology for a coastal ship with endogenous decision of sailing pattern. • Study the properties of the optimal sailing speed under fuel switching and scrubber installation strategies. • Derive the sufficient and necessary condition for a coastal ship of adopting scrubber installation strategy. • Discuss the incentive of evasion behavior and effect on emissions within ECA.. [ABSTRACT FROM AUTHOR]

This study explores emissions regulation of a 3.5 kW single cylinder, direct injection, diesel engine fuelled with biogas and Mahua biodiesel. By varying the compression ratio from 17 to 18 with a step of 0.5, pilot fuel injection timing by 3° BTDC from 23° BTDC to 32° BTDC, and engine load from 20% to 100% with a step of 20%, the optimal operating conditions are determined using response surface methodology. At the optimum engine operating parameter settings of a 17.73 compression ratio, 26.71° BTDC pilot fuel injection timing, and 58.96% engine load, the optimum emissions are 42.89 ppm for NOx, 80.36 ppm for UHC, 4.23% Vol. for CO 2 , and 77.72 ppm for CO. Additionally, the study demonstrates a comparable brake thermal efficiency of 17.35% with 66.26% pilot fuel substitution, indicating biogas-biodiesel as a sustainable and renewable option for dual-fuel CI compression-ignition engines. • Running biogas biodiesel has resulted in a significant decrement in NOx emissions. • Alteration in compression ratio and injection timing lowered CO and HC emissions. • Maximum optimum attained pilot fuel substitution is 66.26%. • Maximum brake thermal efficiency obtained is of 17.35%. • Optimization attained with best goodness of fit range of 0.86–0.99. [ABSTRACT FROM AUTHOR]

This study aims to derive bioenergy from waste lather fat and citronella grass. Lather fat oil (LFO), citronella grass oil (CGO), a mixture of leather fat oil and citronella grass oil (LFCGO), and a nano-additive-incorporated mixture of lather fat oil and citronella grass oil (NFCO) were synthesized and used in diesel engines as the novelty of this study. ASTM standards were used to investigate and guarantee the fuel's properties. According to the experimental report, the nanoadditive's brake thermal efficiency and brake-specific fuel consumption were more comparable to diesel fuel. Compared to diesel, the NFCO blend reduced hydrocarbon, carbon monoxide, and particulate emissions by 6.48%, 12.33%, and 16.66%, respectively, while carbon dioxide and oxides of nitrogen emissions increased. The experiment's outcomes were verified using an artificial neural network (ANN). The trained model exhibits a remarkable coefficient of determination of 98%, with high R values varying from 0.9075 to 0.9998 and low mean absolute percentage error values ranging from 0.97% to 4.24%. Based on the experimental findings and validation report, it can be concluded that NFCO is an efficient diesel fuel substitute. [Display omitted] • Identified substitute fuel from waste biomass for diesel engine. • Evaluated the engine output responses of waste biomass-based test fuel. • Identified the best fuel modification methods to eliminate the NOx. • Numerically validated the experimental results by ANN. [ABSTRACT FROM AUTHOR]

The urge for cleaner and greener sources of energy is rising day by day. Developed countries are already in process of shifting their energy needs from conventional sources to non-conventional/renewable/green sources of energy. These developed countries are also trying to incorporate developing countries to join the battle against global warming and pollution. Examples, of some non-conventional sources of energy are nuclear energy, wind energy etc. One of such cleaner energy source is hydrogen. The high calorific value, availability in abundance and cleaner nature of hydrogen makes it an appropriate substitute for conventional source of energy. An engine using gaseous hydrogen is in the process of being developed. This may revolutionize the battle against pollution and global warming. Use of hydrogen in a diesel engine working on dual-fuel mode has been the interest of many researchers. However utilization of hydrogen fuel changes the ignition delay, combustion duration, peak mean temperature, peak pressure and other combustion parameters change. In the present work, such research works are examined and analyzed in detail. It is also shown, amount of inducted hydrogen dictates many engine parameters such as engine power, torque etc. a separate section is dedicated to study different emissions from the improvised engine. Lastly, it will be clear from the discussion that introduction of gaseous hydrogen to a diesel engine working on dual fuel mode will have optimistic effect on environment. [Display omitted] • The high calorific value, availability in abundance and cleaner nature of H 2. • An engine using gaseous hydrogen is in the process of being developed. • Use of gaseous H 2 to a diesel engine will have optimistic effect on environment. • Combustion parameters like ID, CD and mean temperature of gas increases. • NOx increases with substitution of hydrogen fuel. [ABSTRACT FROM AUTHOR]

The substitution of fossil fuels with renewable energy sources such as hydrogen is a decisive factor in making aviation environmentally compatible. A key parameter for the use of hydrogen is the storage system. In the design of a flight-capable storage system, not only the mass but especially the volume of the hydrogen has to be considered. Therefore, in this paper different techniques are compared and evaluated from the point of view of their application in aircraft design. The analyses are performed on two reference aircraft, the Airbus A320 and the Embraer E 190, in the short- and medium-haul range. Simplified, it is assumed that the respective max. Take-off mass (MTOM) remains constant. The change of the necessary periphery has no influence on the MTOM. A tank concept could be designed, which can find applications in today's conventional aircraft design. • Energy consumption calculated for A320 and E 190. • Flight data evaluation. • Comparison of different storage methods. • Calculation of volumes for different storage methods and ambient pressures. • Discussion about possible constructive misplacement. [ABSTRACT FROM AUTHOR]

Trucks has caused serious atmospheric pollutant and greenhouse gas emissions in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA), China, while substituting the truck fuel (gasoline/diesel) by green hydrogen is a critical way to solve the problems. Accordingly, we established a Hydrogen availability-Greenhouse gas and Atmospheric Pollutant emission reduction (HGAP) evaluation model. We revealed that the annual available green hydrogen energy in the GBA reached 1.36 × 1010 GJ, which could fuel all the trucks in the region. Via truck fuel substitution by hydrogen, a 45% reduction in regional greenhouse gas emissions in the GBA could achieve. The emission reductions of CO and HC by vehicles in the GBA achieved approximately 1/4, NOx was about 1/2 and PM was about 60%. We served a solution of developing without eco-sacrifice for developed, strategic yet high-emission coastal regions and countries. • A solution of developing without eco-sacrifice for strategic yet high-emission China GBA. • The H 2 availability in the China GBA is 1.36 × 1010 GJ/a able to fuel all trucks in the region. • A 45% reduction in regional greenhouse gas emissions in the China GBA. • Up to 60% emission reductions of atmospheric pollutants by vehicles in the China GBA. [ABSTRACT FROM AUTHOR]

With the increasing sludge production and cement carbon emissions worldwide, there is an urgent need to develop synergistic approaches to sludge co-process in cement kilns options for building up an interactive sludge carbon reduction process. Cement kilns with temperatures as high as 1450 °C can dissipate various wastes and completely decompose or solidify harmful substances, including dioxins and heavy metals, in the cement crystal structure. Therefore, cooperative cement kiln disposal of sludge can thoroughly decompose organic components as well as their intrinsically cured heavy metals. The vast majority of cement production lines in the world are already equipped for co-process, but the disposal of sludge is blended at a relatively small amount of about 6%. This paper first summarizes the physicochemical characteristics of different types of sludge. In addition, the discussion focuses on the sludge raw material substitution principle and the heavy metal solidification process. The mechanism of K+, Na+, and Cl- plasma damage is further investigated in depth. The overview study predicts the annual carbon emission reduction content of about 25 million tons from two routes of cement kiln co-process of sludge and other solid wastes such as raw material substitution and alternative fuels and cross industries. [Display omitted] • The feasibility of cement kiln co-processing of sludge was critically discussed. • The solidification mechanism of heavy metals in cement production was analyzed. • The mechanism of harmful ions to cement kilns was revealed. [ABSTRACT FROM AUTHOR]

This work utilized the conventional transesterification process to convert waste pork fat into pork fat biodiesel. The produced biodiesel was meant to serve as a diesel fuel substitution for common rail direct injection (CRDI) diesel engines. Butylated Hydroxytoluene (BHT) as an antioxidant doping with waste pork fat biodiesel-diesel blend has not been analyzed in CRDI diesel engines. Therefore, to improve the ignition process and reduce the engine exhaust emissions in a research CRDI diesel engine, the BHT was employed to combine with diesel-biodiesel mixtures in this work. BHT antioxidants are partially mixed (BHT 50, 100, and 150 ppm) to improve the physicochemical qualities of test fuel and enhance the combustion process of diesel-biodiesel blends (B20). The antioxidant purity was analyzed by energy dispersive X-ray analysis (EDX), structures were analyzed by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) analyzer spectrograph was utilized to study the biodiesel chemical components. After mixing the BHT, the overall phase of the base fuel remained constant. The experiment outcomes revealed that the biodiesel had higher cylinder pressure than the other test fuels, and the BHT100 ppm blend had a higher heat release rate (HRR). B20BHT100 blend shows 3.98% higher brake thermal efficiency (BTE) at full load operation than pure biodiesel but lowered to diesel fuel. Biodiesel (B100) decreases the smoke opacity by 4.5% compared to diesel fuel. BHT has been incorporated into the biodiesel blend to minimize oxides of nitrogen (NOx) emissions at all loads. The B20BHT150 blend decreased NOx emissions by 5.06% more than diesel fuel at maximum load. Compared to pure biodiesel, the B20 blends reduce carbon monoxide (CO) emissions by 7.1% and hydrocarbon emission (HC) by 12.5%. This research found that adding BHT to biodiesel blends lowers NOx emissions with a slight impact on performance. [Display omitted] [ABSTRACT FROM AUTHOR]

Nanostructures present favorable prospects of manufacturing high-performing air electrodes for reversible solid oxide fuel cells (RSOFCs) with the potential to reduce their operating temperature. Here, we present trichloroacetic acid as an original infiltration agent for the facile nanoengineering of RSOFC electrodes. The new process relies on the thermal decomposition of trichloroacetic acid in water at temperatures above 70 °C, which causes intense CO 2 effervescence and crystallizes out the metal ions in the solution as slightly soluble carbonates. Essentially, this allows for the subsequent infiltration step to be performed immediately after drying, as opposed to conventional infiltration, which requires high-temperature calcination after each infiltration step. The anode-supported RSOFC consisting of a nanostructured LaCoO 3 air electrode permitted smooth switching between fuel cell and electrolysis cell modes with no evidence of degradation. In addition, the RSOFC presented exceedingly durable performance during accelerated stability tests. [Display omitted] • Trichloroacetic acid is introduced as a novelty nanoengineering substance for use in SOCs. • A LaCoO 3 3D-webbed nanostructured air electrode is successfully synthesized. • Excellent performance is achieved in fuel cell and electrolysis mode operations. • No degradation is observed during reversible and current load cycling operations. • Robust performance is reported for 300 h galvanostatic operation at 750 °C. [ABSTRACT FROM AUTHOR]

Vehicle use is associated with negative externalities such as traffic congestion, air pollution, and greenhouse gas emissions. Particularly in the U.S. as a car-oriented country, vehicle use — in terms of vehicle-miles of travel (VMT) — has been on the rise and is projected to increase in the future. To curb the VMT growth and mitigate the associated externalities, policy makers can design informed strategies based on VMT predicted by vehicle use models. However, traditional vehicle use models capture merely the observed heterogeneity across vehicle decision making units (e.g., individuals) and ignore the latent or taste heterogeneity sourced in individuals' attitudes and lifestyle preferences, which may cause biased and inconsistent results that mislead implications for policy makers. To address this research gap, the present study introduces a latent class regression model, where a probabilistic multinomial logit component endogenously classifies a sample of vehicle use observations so as to be homogeneous within and heterogeneous across the classes with respect to VMT. At the same time, a finite set of linear regression equations in the number of the latent classes yields class-specific VMT. The model is estimated on a sample dataset from the State of California identifying three latent classes, verifying the hypothesis of positing vehicle use on both observed and unobserved heterogeneity. The estimation results are analyzed to infer implications of potential policies aiming at reducing VMT through increasing fuel cost and switching to telework, and to evaluate the efficiency of resource allocation to policies by targeting different classes with distinctive characteristics. • Presents a latent class regression model of vehicle use in terms of VMT. • Empirically analyzes the model on a sample data from the State of California. • Identifies 3 classes with heterogeneous characteristics and preferences profiles. • Suggests policies to reduce VMT through higher fuel cost and switching to telework. • Evaluates efficiency of policies targeting classes with distinctive characteristics. [ABSTRACT FROM AUTHOR]

This research demonstrates a palm kernel shell gasification system for producing fuel gas, also known as producer gas. Using air as an oxidant, the gasification process converts palm kernel shells into fuel gas which contains combustible gases, such as hydrogen, carbon monoxide, and methane with nitrogen dominating the composition of the gas. This fuel gas can supply heat via direct combustion or generate electricity for fossil fuel substitution of an internal combustion engine. As a biomass-derived gas, the fuel gas is characterized as carbon-neutral inherently. During the conversion process, the system needs electricity to power the screw feeder, air blowers, and cooling-water pumps, and to rotate the gasifier's bottom plate to take the char out. Based on the experiments, mass balance, and energy balance calculations, this study examines the global warming, acidification, and eutrophication potential using the openLCA v1.10.3 software and Environmental Footprint (MID-Point indicator) database for impacts assessment when the system is operated in Indonesia and Malaysia with various electricity sources. It is found that the feedstock contributed most of the global warming potential and eutrophication potential, while the electricity dominated the acidification potential. This study recommends operation at a lower equivalent ratio to reduce environmental impacts. • Air gasification of palm kernel shells to produce fuel gas was conducted at a 25 kg/h gasifier capacity. • This study assessed the Global Warming, Eutrophication, and Acidification Potentials of the gasification process. • The effects of equivalent ratios on the environmental impacts were evaluated using a life cycle approach. • Palm kernel shells acquisition showed significant environmental impacts. • The scenarios to improve the process included variations of feedstock sources and electricity generation methods. [ABSTRACT FROM AUTHOR]

The Five-Year Plan (FYP) effectively guides China's short- to medium-term development goals, but limited data hinder research on long-term CO 2 performance within the FYP framework. This study compiles sectoral CO 2 emissions from detailed fuels in 1981–2021, employing the input–output model and structural decomposition technique to examine their performance and driving forces. Our results show that the growth rates of national emissions increased continuously from the 6th to the 11th FYP (1981–2011), gradually declined thereafter (2011−2020), but rose significantly in 2021. Urban household emissions per capita fell by 40%, while rural household emissions rose by 209%. The mix effect (or substitution effect) drove households to increase their use of oil and natural gas, reducing reliance on coal. Coal was the primary emissions source in industrial sectors, specifically in manufacturing and utilities. Elevated coal- and oil-related emissions were primarily due to the level effect, whereas the mix effect drove natural gas-related emissions. Manufacturing and construction were major sources of embodied emissions. Emissions intensity had modest mitigation effects, and the input structure effect was relatively low. Our results underscore the need for China to expedite the substitution of fossil fuels with non-fossil energy sources to achieve its low-carbon goals outlined in the 14th FYP. • We examine China's sector-specific CO 2 emissions from fuels during 1981–2021. • China's CO 2 emissions rates have gradually declined since the 12th Five-Year Plan. • Households are increasing oil and gas, reducing their reliance on coal. • Manufacturing and utilities are the primary direct coal emitters. • Manufacturing and construction are the primary sources of embodied emissions. [ABSTRACT FROM AUTHOR]

The Russian invasion of Ukraine on February 24, 2022 entailed the threat of a drastic and sudden reduction of natural gas supply to the European Union. This paper presents a techno-economic analysis of the consequences of a sudden gas supply shock to Austria, one of the most dependent countries on imports of Russian gas. Our analysis comprises (a) a detailed assessment of supply and demand side countermeasures to mitigate the immediate shortfall in Russian gas imports, (b) a mapping of the net reduction in gas supply to industrial sectors to quantify direct economic shocks and expected relative reductions in gross output and (c) the quantification of higher-order economic impacts through using a dynamic out-of-equilibrium input–output model. Our results show that potential economic consequences can range from relatively mild to highly severe, depending on the implementation and success of counteracting mitigation measures. We find that securing alternative gas imports, storage management, and incentivizing fuel switching represent the most important short-term policy levers to mitigate the adverse impacts of a sudden import stop. [ABSTRACT FROM AUTHOR]

Crustacean waste has great potential as fossil fuel substitution and efficient desulfurization to reduce pollutant emissions, but high moisture and poor quality restrict broad-scale utilization. This study used microwave radiation on crayfish shell to investigate the combustion characteristics and desulfurization effect in different atmospheres/pulse microwave cycle. Meanwhile, the structure evolution mechanism and molecular reaction pathways were revealed. The results show that crayfish shell derived fuel has a pleasurable combustion performance and sulfur fixation ability after microwave radiation in flue gas. The heat release of derived fuel increased by 29.9 % after five microwave cycle in flue gas, and activation energy decreased by 3.7 %. By contrast, the heat release increased by 17.4 % after five microwave cycle in inert gas, and activation energy increased by 39.3 %. Subsequently, the effect of microwave cycle times in flue gas on crayfish shell combustion and desulfurization performance was studied. The results show that the heat release of derived fuel gradually increases with microwave cycle. After seven microwave cycle, the derived fuel heat release and SO 2 removal efficiency increased by 34.9 % and 44.4 %, respectively. The results establish the foundation for expanding the utilization pathway of crustacean waste and realizing the low-carbon energy transition. [Display omitted] • Prepared crayfish shell derived fuel use microwave radiation in flue and inert gas. • The effect mechanism of pore structure on combustion performance was elucidated. • Proposed the two reaction pathways of functional groups under microwave radiation. • Microwave radiation in flue gas increased exotherm by 35 % and reduced SO 2 by 44 %. • Crayfish shell derived fuel sync realized the fuel substitution and SO 2 reduction. [ABSTRACT FROM AUTHOR]

Some green technologies and operational measures are commonly used in fleet deployment and scheduling, including fuel switching, scrubbers, LNG fuels, and shore power, to reduce sulfur or carbon emissions. In fact, most green technologies only aim to reduce sulfur emissions, which may lead to an increase in carbon emissions and operating costs sometimes. Thus, this study addresses how to use the four green technologies wisely in different application environments to simultaneously achieve the three objectives of reducing sulfur and carbon emissions and operating costs. Accordingly, a multi-objective mixed-integer nonlinear programming model for the heterogeneous fleet deployment and scheduling is formulated, where four green technologies and different ship types with various ages, capacities, costs, fuel consumptions, and speeds are considered. Then, the non-dominated sorting genetic algorithm II (NSGA-II) is designed to obtain the Pareto front of the triple-objective formulation. The numerical experiments based on COSCO Shipping Lines show that: to reduce carbon and sulfur emissions, ships will gradually change from fuel switching and shore power to scrubbers and LNG fuels. Large ships and new ships should first use scrubbers and/or LNG fuels, and then small ships and old ships switch their green technology selection. Our sensitivity analyses show the change rule of costs and emissions with changing different parameters, which can provide a reference for the selection of green technology and the timing of equipment refitting. • An integrated fleet deployment and scheduling problem with heterogeneous ships considered is proposed. • Four green technologies are compared to explore application scenarios. • A novel multi-objective model is proposed to reduce sulfur and carbon emissions simultaneously. • Findings inform engineering guidance for implementing green technologies in fleet scheduling. [ABSTRACT FROM AUTHOR]

The article looks at the role of electrification that is expanding as a key factor in transitioning to a low-carbon economy. The study is based on a systemic approach and aims to provide a comprehensive understanding of the necessary transformations in energy production and consumption directed at phasing out fossil fuels and advancing the climate agenda. The novelty of the study resides in the development of conceptual foundations of the fuel-saving aspect of electrification which makes it possible to not only significantly reduce the negative environmental effects in regions, but also to ensure intensive economic growth through the application of advanced energy technologies and minimization of the use of a scarce energy carrier - natural gas - in the power industry and industry. The article clarifies the conceptual apparatus, defines the characteristics and patterns of the new stage of electrification, assesses the impact of electrification on the economic growth and environmental safety of the region, gives recommendations on optimizing the technological structure of the electric power industry in the context of the changing requirements for the parameters of electricity supply. The authors propose a methodology for accounting for the environmental factor in the electrification of the region, which includes ranking and selecting facilities to be electrified according to the minimum "electric fuel replacement ratio"; using the associated energy saving effect for financial compensation of the environmental burden, as well as introducing electricity demand management programs that improve the environmental situation in the region. The article defines the sequence of the implementation of the fuel-saving aspect of electrification and formulates a set of progressive solutions that would invigorate the relevant projects. • A framework of the fuel-saving aspect of electrification that implies substitution of hydrocarbon fuel has been designed. • Regularities of structural transformation of the electric power industry amid deeper electrification have been revealed. • Conditions for the introduction of advanced electric technologies for smartization of economic sectors have been determined. • Principles of electrification management in regions with heavy environmental burdens have been identified. • Interdisciplinary solutions for the diversification of the structure of generating capacities have been proposed. [ABSTRACT FROM AUTHOR]

The direct carbon dioxide (CO 2) emissions from the iron and steel sector are nearly 7 % of the global CO 2 emissions from energy use. India is the world's second-largest producer of steel and the largest sponge iron producer. India produces one-third of the global sponge iron, mostly from rotary kilns using coal as an energy source, resulting in higher energy and emission intensities than the global average. This study evaluates major options for CO 2 abatement in the rotary kiln–induction furnace process for steel production. Based on the mass and energy balances of a typical sponge iron plant, this study evaluates the techno-economic potential of nine major decarbonization measures. The proposed decarbonization measures include improved energy efficiency, improved material efficiency, renewable energy use, and fuel substitution. Marginal abatement and green premium curves are generated by incorporating the dependency of different measures. Depending upon the set of options chosen, carbon abatement is in the range of 55.8 %–99.2 %. It is observed that 11.5 %–20.6 % of decarbonization potential can be achieved without any additional cost to the customer. These findings are insightful for policymakers and industry stakeholders and provide a foundation for designing and implementing a net-zero pathway for the sector. • Energy efficiency, material and fuel change, and renewable energy options used. • Techno-economic evaluation of different measures is reported. • Marginal abatement and green premium curves incorporate dependency of the options. • Overall decarbonization of 99.2 % can be achieved. • 20.6 % of carbon abatement can be achieved without additional cost to customers. [ABSTRACT FROM AUTHOR]

Achieving net-zero emissions in the maritime sector requires adopting carbon-neutral practices in terms of shipbuilding, operation and recycling. However, research integrating life cycle and energy analysis is missing to inform decision-makers. Consequently, the paper presents models combining a model-based life cycle assessment (MBLCA) and ship energy simulations to examine the footprints of a generic New Panamax Containership (DTC). Analyses were conducted to assess the energy and carbon effects of using synthetic methanol as marine fuel. The life-cycle analysis confirms the overwhelming prevalence of operations in the total greenhouse gases emission during the ship's lifetime. The analysis highlights the potential of carbon savings if the vessel consumes methanol produced from neutral energy and renewable carbon sources. However, the magnitude of shipping fuel requirements may profoundly impact energy infrastructures while still requiring large volumes of carbon offset credits. The paper confirms the usefulness of integrating life-cycle analysis and energy modelling to discuss future energy scenarios. The completeness of the models also allows for future research analysing other energy solutions. • The paper assesses GWP100, energy intensity, and renewable carbon needs of a New-Panamax vessel using heavy fuel oil or carbon-neutral methanol. • The methodology integrates a novel energy modelling tool into ISO life cycle analysis for maritime decarbonation research. • Findings indicate that operational energy consumption accounts for 60%–98% of the vessel's total carbon footprint. • Results reveal that 80% of the shipbuilding carbon footprint is attributable to the production of steel and main machinery. • The authors underscore the importance of cradle-to-grave approaches, accounting for externalities in fuel substitution strategies supporting decarbonation. [ABSTRACT FROM AUTHOR]

Fuel substitution is an important measure for heat substitution and carbon emissions reduction in cement production by using low-carbon fuels such as solid waste, natural gas, biomass energy and solar energy. In this study, a technology that uses concentrated solar energy to directly drive solar cement clinker production is proposed and its feasibility is experimental demonstrated. The results showed that cement clinker could be burned using concentrated solar energy. Because the sintering rate is rapid, rapid burning and/or under-burning also occurs during the sintering process, which causes the clinker structure exhibit a sheet structure. The chemical composition analysis showed that the total mass fraction of dicalcium silicate (C 2 S) and tricalcium silicate (C 3 S) exceeded 70 %, the mass fraction of f-CaO was higher than the standard value (≤1.5 %). Controlling the sintering temperature and time, and increasing the cooling rate are significant factors in ensuring the quality of the cement clinker. [ABSTRACT FROM AUTHOR]

Cooking fuel choice and fuel switching behaviours can be influenced by both social and economic contextual factors; with implications for household air pollution exposure. The Rwandan Government have recently proposed a charcoal sale ban to reduce domestic reliance upon charcoal fuels and reduce associated respiratory health harms. A semi-structured mobile telephone survey administered to 85 participants in an informal settlement in Kigali, Rwanda to identify (i) fuel switching as a result of COVID-19 emergency health protection 'lockdown' measures (ii) awareness of proposed charcoal sale restrictions and willingness to pay for alternative domestic cooking fuels. Of the 85 interviewed participants, 15 (17.6 %) reported a change in primary cooking fuel since the first national COVID-19 emergency 'lockdown' period (March – May), with Liquid Petroleum Gas (LPG) users moving to charcoal (n = 3; 20 %), and charcoal users to firewood (n = 7; 46.7 %) or LPG (n = 4; 26.7 %) and one firewood user to charcoal (n = 1; 6.6 %). Awareness of the forthcoming LPG subsidy (81.5 %) and charcoal ban policy proposals was high among all participants (81.5 %), with 90.7 % indicating they would change their cooking fuel as a consequence. LPG was the preferred alternative fuel of choice (89.8 %), with cost, ease of use and cleanliness reported as rationale. Forty-four percent of participants reported a willingness to pay less, 38 % to pay the same and 25 % to pay more than their current cooking fuel expenditure for a cleaner alternative fuel. Domestic fuel switching as a result of economic and energy market volatility, was observed in an informal settlement in urban Rwanda as a consequence of COVID-19 emergency measures, most notably by substitution of firewood for charcoal, reflecting a regressive step in the energy ladder. Our findings demonstrate a high level of awareness and engagement with forthcoming domestic fuel policy changes in Kigali, and a large proportion of those interviewed would consider transition to cleaner domestic energy sources. This novel primary research has implications for developing domestic energy resilience to disruptive economic impacts and ensuring effective clean fuel policy implementation in East Africa. • COVID-19 health protection measures in Rwanda resulted in energy uncertainty • Households switched from charcoal to wood cooking fuel during COVID-19 lockdown • Switching to more polluting biomass fuels has major health and environmental risks • There is high awareness of forthcoming domestic fuel policy changes in Rwanda [ABSTRACT FROM AUTHOR]

Isopropanol has a good potential as a new fuel substitution. In the model biosynthesis pathway of isopropanol synthesis, acetoacetyl-CoA is converted to acetoacetate by acetoacetyl-CoA transferases, which requires an acetate molecule as a substrate. Herein, a novel isopropanol synthesis pathway based on mammalian ketone metabolic pathway was developed. In this pathway, acetoacetyl-CoA is condensed with acetyl-CoA to generate 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) by HMG-CoA synthase, and then catalyzed by HMG-CoA lyase to generate acetoacetate. This process is acetate-independent. Under the same experimental system using glycerol as carbon source, the E. coli strain MG::ISOP1 containing the novel pathway produced 11.7 times more isopropanol than the strain MG::ISOP0 containing the model pathway. The pta-ackA knockout mutant strain MG∆ pta-ackA ::ISOP1, which reduced the conversion of acetyl-CoA to acetate, further increased the production from 76 mg/L to 360 mg/L. In another strategy, knocking out atoDA to block the acetoacetate degradation pathway in strain MG∆ atoDA ::ISOP1 increased the production to 680 mg/L. By knocking out both of pta-ackA and atoDA , strain MGΔ pta-ackA Δ atoDA ::ISOP1 produced 964 mg/L of isopropanol, which was 12.7 times that of MG::ISOP1. This study indicated that the novel pathway is competent for isopropanol synthesis, and provides a new perspective for biosynthesis of isopropanol. • A novel pathway was created for synthesis of isopropanol in E. coli. • Reducing acetate synthesis increased isopropanol production. • Blocking the degradation pathway of acetoacetyl-CoA significantly improved the performance of the novel isopropanol synthesis pathway. [ABSTRACT FROM AUTHOR]

The European Hydrogen Strategy and the new « Fit for 55 » package indicate the urgent need for the alignment of policy with the European Green Deal and European Union (EU) climate law for the decarbonization of the energy system and the use of hydrogen towards 2030 and 2050. The increasing carbon prices in EU Emission Trading System (ETS) as well as the lack of dispatchable thermal power generation as part of the Coal exit are expected to enhance the role of Combined Heat and Power (CHP) in the future energy system. In the present work, the use of renewable hydrogen for the decarbonization of CHP plants is investigated for various fossil fuel substitution ratios and the impact of the overall efficiency, the reduction of direct emissions and the carbon footprint of heat and power generation are reported. The analysis provides insights on efficient and decarbonized cogeneration linking the power with the heat sector via renewable hydrogen production and use. The levelized cost of hydrogen production as well as the levelized cost of electricity in the power to hydrogen to combined heat and power system are analyzed for various natural gas substitution scenarios as well as current and future projections of EU ETS carbon prices. [Display omitted] • Modelling of Power to Hydrogen to Combined Heat and Power plant in Aspen Plus. • Variations of electric, thermal, CHP efficiencies and emissions for various hydrogen substitution ratios. • LCOH and LCOE for various capacity factors of the integrated system. • LCOE comparison of the proposed system for various carbon and natural gas prices as well as hydrogen substitution ratios. • Overall roundtrip efficiencies of the PtH 2 tCHP and PtH 2 tP system for 100% H 2 equal to 44.21% and 11.76% respectively. [ABSTRACT FROM AUTHOR]

The present study examined the potential of utilizing hydrogen as a fuel in an industrial cross-fired oxy-fuel glass melting furnace with a total energy input of 3.9 MW. To this end, comprehensive three-dimensional CFD simulations were performed in Ansys Fluent, employing a coupled numerical model from preceding works. A two-step validation process was presented, comprising the validation of both the numerical furnace setup and the modeling of industrial oxy-fuel combustion setups using hydrogen as a fuel gas. Assuming an equal thermal energy input for both combustion conditions, the fuel/oxidizer ratios of velocity and momentum of the six PrimeFire burners were found to be significantly affected. Consequently, the low-momentum flames with natural gas transformed into jet-type flames with a straighter trajectory when transitioning to hydrogen. This change led to an enhanced turbulent mixing and a reduction of flame lengths by over 25%, while the average flame temperature increased by up to 82 K due to the accelerated reaction kinetics. In addition, the elevated flame momentum in the cross-fired burner configuration resulted in a localized rise in maximum side wall temperatures by more than 20 K. With the exception of these local effects, the global temperature distribution and heat transfer mechanisms were not significantly impacted. This indicated a comparable melting process and furnace efficiency, while still allowing for a reduction of total CO 2 emissions by 77.5%. Future research should concentrate on both the impact on glass quality and the evaluation of potential alternative burner configurations for hydrogen-fired oxy-fuel glass melting furnaces. • CFD study of a cross-fired 3.9 MW oxy-fuel glass melting furnace using NG and H 2. • Evaluation of H 2 effects on local flame characteristics and global furnace operation. • Observation of a significant change in turbulent mixing phenomena and flame shapes. • Minor influence of fuel switch on heat transfer and general furnace efficiency. • Potential reduction of total CO 2 emissions by 77.5% in the current furnace. [ABSTRACT FROM AUTHOR]

Most energy scenario studies typically focus on technological options and fuel substitution for decarbonising future energy systems. Lifestyle changes are rarely considered, although they can significantly reduce energy demand and climate change mitigation efforts. By using an energy system model, this study shows that it is possible to reduce final energy demand in Germany by 61 % in 2050 relative to 2019 levels, resulting in an annual per capita energy demand of 44 GJ for a representative country of the Global North. This goal can be achieved through a combination of technological measures and lifestyle changes without sacrificing a decent standard of living. Societal chances can eliminate reliance on not-yet-established negative emission technologies, reduce energy dependency, and reduce the need for energy-intensive hydrogen and e-fuels. Downsizing the energy system provides an opportunity for strengthening climate change mitigation, decrease material demand and reduce land use. [Display omitted] • Modelling a low energy demand scenario for Germany, including lifestyle changes. • Lifestyle changes combined with technological options enable reductions in energy demand and greenhouse gas emissions. • Lifestyle changes can reduce or eliminate reliance on negative emission technologies. • Per capita final energy demand in Germany can be reduced to 44 GJ in 2050. [ABSTRACT FROM AUTHOR]

Reversible solid oxide cells (RSOCs) is a promising energy storage and conversion technology requiring frequent switching between fuel cell mode and electrolysis mode in practice. Unfortunately, it may cause a large current density undershoot that has irreversible damage to the RSOC. Therefore, understanding the transient behaviors of the RSOC is critical for its efficient and durable operation. A three-dimensional transient model of a 30-cell SOC stack with an external manifold is established. From SOFC to SOEC, the mass transfer lag and slow heat transfer cause the current density of the stack requiring 2500 s to reach a steady state. And the bottom inlet way and the external manifold structure cause differences in the current density, molar fraction and temperature variation with time between different cells. The upper cells show a slower mass transfer rate and undergo greater temperature changes. The inconsistent temperature change gradients and temperature change rates among different cells will inevitably produce changing thermal stresses and bring irreversible mechanical losses to the stack. Similar transient characteristics are observed when switching from SOEC to SOFC. However, it takes longer time (3200 s) to achieve the final steady state. • A three dimension transient model of a 30-cell RSOC stack is developed. • The current density, molar fraction, and temperature variation in different cells are compared. • The upper lever cells show a slower mass transfer rate and undergo greater temperature changes. • Heat transfer determines the time for mode switching to reach the final steady state. • More complex transient behaviors are exhibited from SOFC to SOEC mode. [ABSTRACT FROM AUTHOR]

Dual fuel combustion of low calorific industrial gas has been widely used in various types of burners for industrial production needs. Fuel switching rule is purely empirical lacking theoretic basis, potentially leading to flame extinction or excessive waste of ignition fuel. This study focuses on exploring physics-guided fuel-switching strategy for stable combustion of coke oven gas (COG) and blast furnace gas (BFG) in representative swirl burner. Stable operating regimes for COG and BFG are firstly identified with chemical eigen-analysis. The intrinsic propensity of flame extinction during fuel switching is revealed by positive chemical eigenvalues, and the key species and elementary reactions are identified. A clustered neural network with flag controller (CNNF) is then constructed to achieve stable combustion during fuel switching from COG to BFG as early as possible to reduce the use of COG. Results show that COG must be used to ignite and increase the ambient temperature to at least 673 K to avoid flame extinction. The chemical eigen-guided CNNF controller can adjust the switch speed to advance the fuel switching time by 14 % and can be further expanded to other fuel switching applications. • Fuel switching properties are analyzed with PSR model. • Eigen-analysis is used to find key species and reactions. • An active neural network controller is constructed. [ABSTRACT FROM AUTHOR]

The electric vehicle (EV) transition is underway in the UK and many other countries worldwide, switching from fossil fuel powered internal combustion engine (ICE) road transport to EVs that can be powered by renewable electricity. Whilst the projected energy and carbon reduction impacts are well understood, we have only a partial view of the potential socio-macroeconomic effects of the EV transition, i.e. the impacts on GDP and jobs. Common energy-economy models feature only limited energy-economy integration, and only assign a small role for energy in economic growth. Thus whilst economic changes such as increases to investment can feed into macroeconomic impact assessment, the impacts of the energy system changes are potentially underestimated. In response, we use a novel macro-econometric model – MARCO-UK – to conduct a whole system analysis with two main scenarios: an ICE baseline (with no EV transition) and 100% EV transition scenario to 2050. We investigate the effects of the scenarios on the UK's energy system (efficiency, energy services, rebound) and economic system (employment, GDP, debt), under different conditions of investment, rebound and electricity prices. We find the most significant impacts stem from energy system changes, with annual economic growth rising from 1.71%/year (baseline) to 2.25%/year in the main EV scenario. In contrast, the impacts from economic investment changes are much lower in scale. Therefore, the socio-macroeconomic benefits of the EV transition may be underestimated. We also find that overall long-term economy-wide rebound in our central EV scenario is 76%, which means the energy savings from the EV transition may be less than hoped. Overall, our analysis identifies potential trade-offs regarding the labour market, levels of indebtedness, energy rebound and associated carbon emissions that should be taken into consideration. • The energy and socioeconomic impacts of the UK's EV transition are not well known. • We model energy changes to efficiency and fuel switch to electricity. • Most significant impacts stem from energy system change not investment stimulus. • The EV transition could realise an extra 0.5%/yr of GDP growth. • But economy-wide rebound effects reduce energy savings from the EV transition. [ABSTRACT FROM AUTHOR]

Today's research concerning power generation and transportation applications is focused on sustainable engine technology solutions. Conventional diesel engines could be retrofitted with Homogeneous Charge Compression Ignition (HCCI) technology to achieve the intended sustainability by effectively utilizing low-carbon/carbon-neutral biofuels. In the present research, a market-ready prototype of an HCCI engine was developed that could be operated using biofuel-gasoline blends with dynamically varying biofuel proportions from 20–60 vol.%, depending on engine load demand. A fixed quantity (6 vol.%) of commercial cetane improver was blended in fuel to prevent combustion misfiring in HCCI mode. The HCCI mode was operated at ambient intake temperature and naturally aspirated conditions without using any thermal strategy for fuel ignition control. There are problems with adopting a single specific biofuel-gasoline-fueled HCCI combustion: blend separation due to water contamination, the tendency to disrupt the food chain by pressurizing farmers to grow a specific food crop, the corrosive nature of biofuel limiting its proportion in the blend, and lesser flexibility to tune blend properties. These shortcomings were alleviated by proposing multiple biofuel-gasoline-fueled HCCI combustion, which is the novelty of the present study. A case study of the 20% acetone in gasoline blend (20AGE) was presented in which diisopropyl ether or n-butanol was added to replace gasoline, addressing the abovementioned drawbacks. Blending 40% diisopropyl ether to replace gasoline in 20AGE produced a maximum increase in the indicated thermal efficiency (ITE) by 1.8 times. It led to a maximum decrease in smoke, oxides of nitrogen, and carbon dioxide emissions by 52%, 38%, and 14%, respectively than 20AGE at the part load conditions. The Fuel Mean Effective Pressure distribution structure was established for the HCCI mode to find the sources of the energy losses impacting the ITE. The Fuel Interchangeability Index was determined for the HCCI mode, using which the interchangeable biofuel-gasoline blends could be identified, considering their crucial fuel parameters. Overall, HCCI combustion using a suitable combination of multiple biofuel-gasoline blends provides a sustainable solution to operate light-duty diesel engines. [Display omitted] • The HCCI combustion phasing was controlled through the variation in fuel composition. • The HCCI engine operated without using any thermal strategy for fuel ignition control. • The Biofuel Interchangeability Index was determined for the HCCI mode. • Fuel Mean Effective Pressure distribution structure was found for the HCCI mode. • The multiple biofuel-gasoline HCCI mode offers a sustainable engine technology. [ABSTRACT FROM AUTHOR]

[Display omitted] • Taxis with failed TWC are super emitters with 30 – 70 times more EFs than normal vehicles. • Failure of TWC is much more important than fuel substitution regarding organic emissions. • IVOCs are proportionally concentrated after TWC failure. Vehicle exhaust is one of the major organic sources in urban areas. Old taxis equipped with failed three-way catalysts (TWCs) have been regarded as "super emitters". Compressed natural gas (CNG) is a regular substitution fuel for gasoline in taxis. The relative effect of fuel substitution and TWC failure has not been thoroughly investigated. In this work, vehicle exhausts from gasoline and CNG taxis with optimally functioning and malfunctioning TWCs are sampled by Tenax TA tubes and then analyzed by a comprehensive two-dimensional gas chromatography-mass spectrometer (GC×GC–MS). A total of 216 organics are quantified, including 80 volatile organic compounds (VOCs) and 132 intermediate volatility organic compounds (IVOCs). Failure of TWC introduces super emitters with 30 – 70 times emission factors (EFs), 60 – 112 times ozone formation potentials (OFPs), and 34 – 92 times secondary organic aerosols (SOAs) more than normal vehicles. Specifically, for the taxi with failed TWC, the total organic EF of CNG is 16 times that of gasoline, indicating that the failure of TWC exceeds the emission reduction achieved by CNG-gasoline substitution. A significant but unbalanced reduction of ozone and SOA is observed after TWC, whereas a notable "enrichment" in IVOCs was observed. Naphthalene is a typical IVOC component strongly associated with CNG-gasoline substitution and TWC failure, which is lacking in current VOC measurement. We especially emphasize that there is an urgent need to scrap vehicles with failed TWCs in order to significantly reduce air pollution. [ABSTRACT FROM AUTHOR]

Multifuel compression ignition (CI) engines have been proven to be useful for the aviation industry, especially for powering unmanned aerial vehicles (UAVs). To operate multifuel UAVs at desired operating conditions, an appropriate control strategy is needed that can adapt based on changing fuel properties. Therefore, having knowledge of fuel properties at all times is critical. However, the challenge comes in identifying fuel property in real-time when fuel switching happens during engine operation. The current work proposes a novel data-driven control algorithm for estimating fuel property (cetane number) and adapting the control strategy in real-time. Gaussian process regression (GPR) is used for modeling the multifuel CI engine, and feedforward control is developed to correct the control inputs based on the estimated fuel cetane property. For feedforward control development, model inversion of data-driven GPR is performed. Based on the estimated fuel property and using the feedforward table, the control strategy gets adjusted in real-time within one combustion cycle to avoid the system performance from drifting away beyond specified bounds. The entire approach was implemented and validated on an engine test bed. Fuel switching is performed in real time, and the results demonstrated the capability of the algorithm to maintain the desired performance. • A novel fuel cetane (CN) estimation algorithm is proposed using data-driven model. • The proposed algorithm estimates fuel CN in real-time during actual engine operation. • A feedforward control is developed in conjunction with the CN estimation algorithm. • The CN estimation and control are validated with fuel switching in real-time. • Results demonstrate the algorithm's efficacy in operating multifuel engines. [ABSTRACT FROM AUTHOR]

As a developing country, South Africa faces the risk of having to undertake disruptive actions to meet its internationally pledged emission reduction targets. It has become necessary to find alternative measures for South Africa to meet its climate targets without such a disruptive and aggressive transformation of its energy sector. To truly reach net-zero CO 2 emissions, South Africa must ensure that residual emissions from its recalcitrant sectors are equally compensated by carbon dioxide removal (CDR). Given the potential for CDR technologies to delay the need for rapid emissions cuts, we leverage this characteristic to explore their role in helping South Africa achieve its climate targets on time, but through a less disruptive and overly aggressive pace of energy system decarbonization. Using an integrated assessment model, we show that while reaching its emission reduction targets, the presence of novel CDR (nCDR) approaches could significantly reduce South Africa's mitigation costs to $155-240/tCO 2 instead of $190–590/tCO 2 by 2050 in the absence of nCDR. Furthermore, the availability of nCDR may allow for a more gradual transition towards renewable and nuclear power generation compared to scenarios without nCDR. Importantly, we reveal that nCDR could help avoid asset stranding of up to 4–6 GW and $15–25 billion in associated costs between 2016 and 2050. However, this comes at the cost of higher residual greenhouse gas emissions due to the continued reliance on fossil fuels under nCDR availability. Overall, South Africa's priority must remain on decarbonization, especially in sectors where fuel switching and energy efficiency are feasible. Nonetheless, the complementary role of nCDR must not be underestimated, and South Africa should begin investing in these emerging technologies to support its ambitious climate goals. • Study employs GCAM to model South Africa's net-zero ambitions. • Role of carbon removal technologies explored. • Coal power generation quickly phases down in the absence of CO 2 removal technologies. • The presence of CO 2 removal technologies reduces stranded investments and capacities. • Carbon removal reduces disruptive and over-aggressive energy transition. [ABSTRACT FROM AUTHOR]

• Six alternative or low-carbon fuels are evaluated for the cement sector. • Average long-term marginal abatement costs range from −70 to 138 CAD/tCO 2 e. • Up to 21% of emissions to 2050 can be eliminated with negative abatement costs. • Energy prices are the primary factor driving scenario cost performance. Limiting global warming and the pursuit of a net-zero global society by 2050 emphasizes the need to transform the hard-to-abate industrial sectors. The cement sector is the second-largest source of global industrial emissions, accounting for 8% of worldwide greenhouse gas emissions. Fuel switching in the cement sector is a decarbonization pathway that has not been explored in detail; previous studies involving fuel switching in the sector either view it from an energy efficiency lens or focus on a single technology. In this study, a framework is developed to evaluate and directly compare six fuel switching options (including hydrogen, biomass, municipal solid waste, and natural gas) from 2020 to 2050. Capital costs, non-energy operating costs, energy costs, and carbon costs are used to calculate marginal abatement costs and emulate cost based-market decisions. The developed framework is used to conduct a case study for Canada, using the LEAP-Canada model. This study shows that cumulative energy-related greenhouse gas emissions can be reduced by up to 21% between 2020 and 2050 with negative marginal abatement costs. Multiple fuel switching decarbonization pathways were established, reducing the likelihood that locality prevents meaningful emissions reduction and suggesting that, with low-carbon fuel and electricity policies, the sector can take significant steps towards emissions reduction. The developed framework can be applied to jurisdictions around the world for decision making, as nations move towards eliminating emissions from cement production. [ABSTRACT FROM AUTHOR]

Many countries, industries, companies and end consumers have actively switched from fuel cars to electric vehicles (EV) to combat global warming via emission control. However, given cost and research and development uncertainties, refrigerated truck manufacturers (RTMs) and cold-chain logistics enterprises (CCLEs) are hesitant to update and employ electric refrigerated trucks (ERTs). Government support, notably subsidies, is vital in the ERT promotion. Thus, this study investigates the optimal two-sided support policies of the government (i.e. subsidies for CCLEs and RTMs) to explore how it achieves the best incentive for ERT promotion in the cold-chain logistics with limited resources. The study develops an evolutionary game model to analyse the influence of multiple factors on ERT upgrade and penetration strategies, clarify dynamic subsidy policy adjustment measures based on industrial evolution under multiple-factor interactions, and discuss the dynamic adjustment priority of the two-sided subsidy policies. The results indicate that the two-sided hierarchical subsidy policy can improve the promotion of ERTs and stimulate the electrification development of the cold-chain transportation industry. Finally, the decision-making preferences of RTMs and CCLEs in multiple scenarios are discussed and feasible management suggestions for government and enterprises are proposed accordingly. • The study develops an evolutionary game model to analyse the EV promotion in the cold-chain logistics. • We clarify dynamic subsidy policy based on industrial evolution under multiple-factor interactions. • Two-sided hierarchical subsidy policy can improve the use of NERTs in the cold-chain logistics. • The decision-making preferences of RTMs and CCLEs in multiple scenarios are discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Singapore kept its stale policy while targeting a zero-waste Circular Economy plan. • In 2019, Shanghai enhanced household waste segregation and recycling at the source. • Differences were assessed in strategy, environmental, economic and social perspectives. • New policies and digitalisation improved waste management in Shanghai in 2019. • Digitalisation, market reshaping and COVID-19 triggered challenges and opportunities. Due to rapid economic development and urbanisation, emerging megacities with dense populations have witnessed a significant increase in waste generation. Megacities face challenges in developing sustainable waste management systems. Considerable heterogeneity exists across megacities in management strategies. The two selected emerging megacities, Singapore (a city-state) and Shanghai, have similar developmental characteristics, but their waste management modes differ strikingly. This study assessed the two modes in terms of management strategies, environmental effects, economic costs, and social outcomes. Environmental footprint analysis and cost quantification were employed for the assessment based on public data. The research results would permit a deeper understanding of the long-term sustainability of each mode while considering the feasibility of implementation across different contexts. It was found that the waste management system in Singapore had a relatively lower environmental impact than Shanghai before Shanghai's new waste segregation and recycling policy in 2019. However, when the effect of fossil fuel substitution is taken into account, the environmental burden in Shanghai can be lowered more substantially than the one in Singapore. Although Shanghai had more economic burden for the waste segregation at source, it tended to implement the circular economy principles (e.g., reduce, reuse, and recycling) better and improve its sense of community significantly. Based on the practical experiences from the two representative megacities, suggestions for better waste management practices were provided for Singapore, Shanghai, and other emerging megacities with similar circumstances. In addition, challenges and opportunities related to household waste segregation and recycling were identified to guide future practices in emerging megacities. [ABSTRACT FROM AUTHOR]

This study aims to develop a model for the integrated evaluation of woody biomass heat utilization considering the environment, economy, and society. Herein, a woody biomass heat utilization business was virtually operated at Mt. Rokko, Kobe, Japan. In the societal impact assessment, a questionnaire survey was conducted to clarify tourist opinions regarding the hypothetical hot bath facility, and its societal value was estimated using the contingent valuation method. The total benefit estimated based on the willingness to pay was 5.92 million USD. In the economic evaluation, an economic model was constructed using life cycle cost. If kerosene was added to the wood chips, the optimum scale of the wood chip boiler installed was 687 kW, and the fossil fuel substitution rate reached 95.9%. The difference between the annual cost was −126.74–100.12 thousand USD. In the environmental impact assessment, a life cycle assessment was conducted to clarify how the use of woody biomass heat may change the environmental impact of the hypothesized hot bath facility. The net greenhouse gas emissions per 1 GJ were −69.9 kg-CO 2eq /GJ in kerosene. [ABSTRACT FROM AUTHOR]

[Display omitted] • A fast transition to an almost fossil-free future is expected. • The transition will have profound implications on catalysis. • Develop a new catalysis, indicated as reactive, is required for this transition. • A science and technology gap exists to pass from thermal to reactive catalysis. • The case study of solar ammonia (NRR) is discussed to illustrate the need of this change. The substitution of fossil fuels requires redesigning chemical processes and this has major implications on catalysis. In this viewpoint, after analyzing the motivations why this transition to an almost fossil-free future will likely occur faster than often indicated, it is remarked the presence of a science and technology gap to pass from today catalysis to that dominant in the future scenario indicated with the term "reactive" catalysis. It defines catalysis operating in the presence of the highly reactive species generated either i) by application of a potential and electrical current or ii) by light absorption with creation of charge separation, or iii) by activation of the reactant molecules when generating a non-thermal plasma. It requires a different conceptual approach from "thermal" catalysis, where heat is the energy form provided to overcome the activation barrier. Reactive catalysis is not just an extension of that in use (thermal catalysis), but requires to redesign materials and related concepts, including in terms of fundamental science and technology aspects to understand and improve their behavior. The case study of solar ammonia (direct synthesis from N 2 , i.e., nitrogen reduction reaction - NRR) was used to illustrate the need of this change and some of the open questions to solve. [ABSTRACT FROM AUTHOR]

Future asteroid landing and sample return missions will seek for landing sites with high scientific value, such as hazardous terrains, which means that the spacecraft needs the ability of autonomous hazard avoidance. Nowadays, the guidance algorithm based on artificial potential function plays an increasingly important role in hazard avoidance, but the local minimum problem makes that the spacecraft cannot reach the desired target landing point in some complex terrains. In this paper, a novel hazard avoidance guidance method which improves the traditional artificial potential function is developed. This method focuses on the impact zone analysis of hazards and defines anti-collision zone. In addition, a new repulsive potential function in logarithmic form is designed with continuity and fast numerical change rate in the anti-collision zone on this basis, and the problem of spacecraft falling into local minimum zone in complex terrains can be effectively avoided. Considering the practical application of constant thrust engine, the hazard avoidance control law with constant thrust sliding mode is designed to reduce switching frequency and fuel consumption. The performance of the proposed guidance law is verified through a set of simulations, as well as the global stability of the control system under uncertainty and perturbation conditions. • A novel hazard avoidance guidance for asteroid landing with constant thrust is proposed. • The concept of anti-collision zone is presented based on the impact zone analysis of hazards. • A new potential function in logarithmic form is established to avoid local minimum problem. • The constant thrust sliding mode control law is developed to reduce fuel consumption. [ABSTRACT FROM AUTHOR]

Despite the massive electrification of the energy sector, combustion-based technologies will continue to play a key role for decades to come. Therefore , to meet the ambitious target of decarbonization of the energy sector, adapting current technologies to alternative energy sources, like biofuels, is a must. The proposed work aims at investigating the role of biomass producer gas in compression ignition (CI) engines, as a substitute of diesel fuel. A micro combined heat and power generation system (CHP) consisting of an open-top downdraft gasifier, a single-cylinder water-cooled CI engine and a waste heat recovery circuit have been set-up with the aim to investigate emissions and performance at several Diesel Substitution Rates (DSR), up to 50 %. Maximum substitution levels – which occur due to knocking limitations and combustion instabilities - have been also identified. The main results show: i) a decrease of thermal and electrical efficiencies in the range of 10–30 %; ii) strong NO x and smoke opacity reductions (with peaks close to 80 %); iii) an increase of CO emissions (above 50 %); iv) the assessment of a decreasing maximum DSR as the power load increase (98 % at the lowest load, up to 46 % at full load). Such findings offer quantitative results through which multi-objective optimization procedures could be implemented. Moreover, experimental results indicate the need for a diesel injection timing optimization strategy to mitigate CO emissions. • Dual fuel combustion (producer gas/diesel) is realized in a direct coupled system. • Smoke opacity and NOx emissions are strongly reduced thanks to producer gas addition. • CO critical levels need optimization strategies. • Knocking phenomena and combustion instabilities limit the diesel substitution. [ABSTRACT FROM AUTHOR]

Alternative fuels and stocks like biomass or chemical and refinery waste, may potentially be used in gas turbines and industrial applications after gasification. Thus, understanding the role of hydrogen in these fuels is critical to the broader aim of utilising alternative fuels for power generation. In this work, the interaction between the flame and the flow field was studied in a quarl-stabilised swirl non-premixed flame burning CH 4 and H 2 –enriched CH 4. Simultaneous high-speed OH-PLIF/PIV imaging at 5 kHz was carried out on these flames to explore the flame-flow interaction. The instantaneous flow fields in the CH 4 or CH 4 +H 2 flames showed a small scale vortical structure near the shear layers, which were not apparent in the time-averaged flow fields. Increasing H 2 % in the fuel jet was observed to dampen the velocity fluctuations. The fuel composition affected the spatial location of the reaction zone; in the CH 4 flames, the axial position of the reaction zone is seen to track the relatively large-magnitude axial velocity fluctuations while remaining in locally low-speed regions of the flow. In contrast, in H 2 -enriched flames, where the flame is more robust, the reaction zone was able to survive longer, in terms of axial distance, in the vicinity of high swirling jet velocity, with less sensitivity to velocity fluctuations. With increasing the H 2 %, the reaction zone steadily leaves the IRZ towards the swirling jet flow and localised between its outer and inner vortices. This acts as a stabilisation factor where the internal vortices convect hot product towards the fresh mixture. Moreover, the flame curvatures, the vorticity and compressive strain fields interactions with the reaction zone are presented and discussed. This article outlines results that yield more in-depth insight into hydrogen-enriched hydrocarbon non-premixed swirling flames' combustion, which is essential to accelerate the fuel switching from hydrocarbons to hydrogen. [Display omitted] • Decarbonisation of the energy sector is a complex process that includes different approaches to a low carbon energy future. • Thus, there is a considerable promise of using hydrogen-blended fuels in different power generation systems. • Three swirling flames are studied in the current work, differing only in the H 2 % associated with the methane jet. • High-speed OH-PLIF/PIV imaging was carried out on these flames to explore the flame-flow interaction. • The reaction zone for the pure methane flames resides mainly in the regions of low-axial velocity fluid. • In the H 2 -enriched flames, the reaction zone is sustained in the vicinity of high swirling jet velocity. [ABSTRACT FROM AUTHOR]

As the transport sector is ought to be decarbonized, fuel-cell-powered trains are a viable zero-tailpipe technology alternative to the widely employed diesel multiple units in regional railway service on non-electrified tracks. Carbon-free hydrogen can be provided by water-electrolysis from renewable energies. In this study we introduce an approach to assess the potential of wind-based hydrogen for use in adjacent regional rail transport by applying a GIS approach in conjunction with a site-level cost model. In Brandenburg about 10.1 million train-km annually could be switched to fuel cell electric train operation. This relates to a diesel consumption of appr. 9.5 million liters today. If fuel cell trains would be employed, that translated to 2198 annual tons hydrogen annually. At favorable sites hydrogen costs of approx. 6.40 €/kg - including costs of hydrogen refueling stations - could be achieved. Making excess hydrogen available for other consumers, would further decrease hydrogen production costs. • Geocost-model to assess local wind hydrogen production for fuel cell powered trains. • Sufficient track-adjacent windmills in Brandenburg to provide FC train operation. • Minimum costs of 6,4 €/kg H 2 for on-site electrolysis hydrogen for the study region. [ABSTRACT FROM AUTHOR]

[Display omitted] • Methanol synthesis via carbon dioxide hydrogenation is reviewed. • Up to date review on high yield catalysts for methanol synthesis are discussed. • Catalytic performance parameters (temperature, Pressure, Support) are reviewed. • Policy framework towards renewable energy for China is extensively reviewed. • The catalytic mechanism and the role of promoters, bi-metallic catalyst is also discussed. A unified treatment of the renewable portfolio standards is given concerning direct methanol fuel. The current mechanism of electrocatalysis of methanol oxidation on platinum and non-platinum-containing alloys is summarized for the systematic improvement of the rate of electro-oxidation of methanol are discussed. Policy realignment under the five-year plan is discussed in length to demonstrate how policy, markets, and engineering designs contribute towards the development of model direct methanol fuel cells operational enhancement, and factors that affect critical performance parameters for commercial exploitation are summarized for catalytic formulations and cell design within the context of why this investment in technology, education, and finances is required within the global context of sustainable energy and energy independence as exposed by thirteenth the five-year plan. The prolog focuses on the way, whereas the section on methanol fuel cells on the how and the post log on what is expected post-COVID-19 era in science and technology as China pivots to a post-fossil fuel economy. China's industrial growth has been through internal market reforms and supplies side economics from the Chinese markets for fossil fuels except for petroleum. The latest renewable portfolio standards adopted have common elements as adopted from North American and the United Kingdom in terms of adaptation of obligation in terms of renewable portfolio standards as well as a realization that the necessity for renewables standards for the thirteen five year plan (from 2016 to 2020) need to less rigorously implemented due to performance targets that were met during the eleventh (06–10) and twelfth five-year plans (11–15) in terms of utilization of small coal-ire power plants, development of newer standards, led to an improvement of energy efficiency of 15 %, reduction of SO x /NO x by an average of 90 % and PM2.5 by 96 % over the last two five-year plans. The current phase of the plan has a focus on energy generation from coal and a slowing down of renewables or Renewable energy curtailment of approximately 400 T Wh renewables including 300 T Wh of non-hydro power, principally from Guangdong, and Jiangsu for transfer of hydropower and Zhejiang, Tianjin, Henan for non-hydro power transfer with Beijing and Shanghai playing important roles in renewables energy curtailment and realignment using an integrated approach to optimize each provinces energy portfolio. The realignment of the renewable energy portfolio indicates that the newly installed capacity in Sichuan, Yunnan, Inner Mongolia, and Zhejiang will account for less than 20 % of the current renewable energy portfolio but with the NO x SO x and PM 2.5 savings already accrued. The catalytic reduction of carbon dioxide to methanol (70 / 110 million metric tons from all sources in 2019 for China/world) is one technological approach to reduce global carbon dioxide emissions and suggests that catalytic methanol synthesis by CO 2 hydrogenation may be a plausible approach, even if it is more expensive economically than methanol synthesis by the syngas approach. This is because the CO 2 emissions of the synthesis are lower than other synthesis methodologies. The Chinese government has placed a premium on cleaner air and water and may view such an approach as solving the dual issues of fuel substitution and reduction of CO 2. Thus, the coupling of hydrogen generation from sustainable energies sources (Solar 175 / 509 GW) or wind (211/591.5 GW in 2019) may be an attractive approach, as this requires slightly less water than coal gasification. Due to the thermodynamic requirement of lower operating pressure and higher operating pressure, currently, there is no single operational approach, although some practice approaches (220 °C at 48 atm using copper) and zinc oxide/alumina are suggested for optimal performance. [ABSTRACT FROM AUTHOR]