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Environmental sustainability encompasses various problems, including clean air, renewable energy, climate change, safe environments, and the capacity to live in a healthy community. One possible strategy for addressing these global problems is the circular bio-economy. Cleaner and lower-carbon environments may be fostered via the production of bioenergy and biomaterials, which can also help to maintain the energy-environment connection. To improve sustainability and the state of the planet, scientists are looking at renewable energy sources like ethanol. Compared to gasoline, ethanol has a reduced carbon footprint and a greater energy density, making it a viable alternative fuel. This study gives an overview of ethanol as a possible alternative fuel for flex-powered power generators in India to meet the goals of the circular bio-economy. This paper details the results of flex-fuel testing conducted on a light-duty power generator using an ethanol-gasoline mix. The findings reveal improved thermal efficiency and lower fuel consumption rates than basic fuel. The emissions of both carbon monoxide and unburned hydrocarbons were shown to be reduced.

During  high-power  optical picosecond pumping of a thin GaAs layer, which is part of the Al x Ga 1 – x As–GaAs–Al x Ga 1 – x As heterostructure, intense stimulated picosecond emission arises in it. The exponential and then linear gains of the components at the front are determined by analyzing spectral-component pulses measured in real time. In this case, the influence of the heating of charge carriers by emission on the front of the components was found. The dependence of the component duration (FWHM) on the characteristic times of rise at the front and of relaxation at the decay (also slowed down by emission heating of carriers) of the component is determined.

Carbon dioxide is a variable gas, and has increased by about 12% every year since 1958. As the atmospheric concentration of carbon dioxide has steadily increased, it is regarded as the major cause of global warming. To reduce the emission of carbon dioxide that is the major cause of global warming, the emission characteristics of carbon dioxide need to be investigated. Especially, the carbon dioxide emission of the equipment used in the execution stage of a construction project is in some degree proportional to fuel consumption, but there exist certain factors that are not proportional to fuel consumption. The methods for calculating carbon dioxide emission include a method using chemical formulas, a method using the Intergovernmental Panel on Climate Change (IPCC) emission factors, and a direct measurement method. Among these three CO 2 calculation methods, the indirect methods have the advantage of easy calculation, but the disadvantage of low reliability, while the direct method has the advantage of accurate information, but the disadvantages of requiring a lot of time and cost and the limitations of measurement. In this study, to overcome the disadvantage of the indirect measurement methods, CO 2 emission was measured using the direct measurement method, and the CO 2 emission characteristics of equipment were analyzed. Also, by comparing them with the values calculated using the indirect methods, the differences between the direct method and the indirect methods were analyzed.

A scientific carbon accounting system can help enterprises reduce carbon emissions. This study took an enterprise in the Yangtze River basin as a case study. The accounting classification of carbon emissions in the life cycle of lime production was assessed, and the composition of the sources of carbon emission was analyzed, covering mining explosives, fuel (diesel, coal), electricity and high-temperature limestone decomposition. Using the IPCC emission factor method, a carbon life cycle emission accounting model for lime production was established. We determined that the carbon dioxide equivalent from producing one ton of quicklime ranged from 1096.68 kg CO2 equiv. to 1176.96 kg CO2 equiv. from 2019 to 2021 in the studied case. The decomposition of limestone at a high temperature was the largest carbon emission source, accounting for 64% of the total carbon emission. Coal combustion was the second major source of carbon emissions, accounting for 31% of total carbon emissions. Based upon the main sources of carbon emission for lime production, carbon emission reduction should focus on CO2 capture technology and fuel optimization. Based on the error transfer method, we calculated that the overall uncertainty of the life cycle carbon emissions of quicklime from 2019 to 2021 are 2.13%, 2.07% and 2.09%, respectively. Using our analysis of carbon emissions, the carbon emission factor of producing one unit of quicklime in the lime enterprise in the Yangtze River basin was determined. Furthermore, this research into carbon emission reduction for lime production can provide a point of reference for the promotion of carbon neutrality in the same industry.

This article presents the results of investigations carried out to evaluate the improvement in combustion, performance, and emission characteristics of a diesel engine fueled with neat petro-diesel (PD), soybean biodiesel (SB), and 50% SB blended PD (PD50SB) by using carbon nanotube (CNT) as an additive. The acid–alkaline-based transesterification process with sodium hydroxide (NaOH) as a catalyst was applied to derive the methyl ester of SB. A mass fraction of 100 ppm CNT nanoparticle was blended with base fuels by using an ultrasonicator and the physiochemical properties were measured based on EN standards. The measured physiochemical properties are in good agreement with standard limits. The experimental evaluations were carried out under varying brake mean effective pressure (BMEP) conditions in a single-cylinder, four-stroke, and natural aspirated research diesel engine at a constant speed of 1500 rpm. The results reveal that the SB and its blend promote shorter ignition delay period (IDP) that is resulting in lower in-cylinder pressure (ICP) and net heat release rate (NHR) compared to PD. The SB and its blend increase the brake specific fuel consumption (BSFC), and reduce the brake specific energy consumption (BSEC) and exhaust gas temperature (EGT), due to lower heating value, and efficient combustion, respectively. As far as the emission characteristics are concerned, the SB and its blend promote lower magnitude of hydrocarbon (HC), carbon monoxide (CO), carbon dioxide (CO 2 ), and smoke emissions compared to PD except for oxides of nitrogen (NO x ) emission. The CNT nanoparticle inclusion with base fuels significantly improves the combustion, performance, and emissions level irrespective of engine load conditions.

Carbon dioxide (CO2) and methane (CH4) emissions from freshwater ecosystems are predicted to increase under climate warming. However, freshwater ecosystems in glacierized regions differ critically from those in non-glacierized regions. The potential emissions of CO2 and CH4 from glacierized environments in the Tibetan Plateau (TP) were only recently recognized. Here, the first direct measurement of CO2 and CH4 emission fluxes and isotopic composition during the spring of 2022 in 13 glacial lakes of the TP revealed that glacial lakes were the previously overlooked CO2 sinks due to chemical weathering in glacierized regions. The daily average CO2 flux was −5.1 ± 4.4 mmol m−2 d−1, and the CO2 consumption could reach 38.9 Gg C-CO2 yr−1 by all glacial lakes in the TP. This consumption might be larger during summer when glaciers experience intensive melting, highlighting the importance of CO2 uptake by glacial lakes on the global carbon cycle. However, the studied glacial lakes were CH4 sources with total emission flux ranging from 4.4 ± 3.3 to 4082.5 ± 795.6 μmol m−2 d−1. The large CH4 range was attributed to ebullition found in three of the glacial lakes. Low dissolved organic carbon concentrations and CH4 oxidation might be responsible for the low CH4 diffusive fluxes of glacial lakes without ebullition. In addition, groundwater input could alter CO2 and CH4 emissions from glacial lakes. CH4 in glacial lakes probably had a thermogenic source; whereas CO2 was influenced mainly by atmospheric input, as well as organic matter remineralization and CH4 oxidation. Overall, glacial lakes in the TP play an important role in the global carbon cycle and budget, and more detailed isotopic and microbial studies are needed to constrain the contributions of different pathways to CO2 and CH4 production, consumption and emissions.

Fossil fuels are the main source of energy for transportation operations around the world. However, fossil fuels cause extremely negative impacts on the environment, as well as uneven distribution across countries, increasing energy insecurity. Biodiesel is one of the potential and feasible options in recent years to solve energy problems. Biodiesel is a renewable, low-carbon fuel source that is increasingly being used as a replacement for traditional fossil fuels, particularly in diesel engines. Biodiesel has several potential benefits such as reducing greenhouse gas emissions, improving air quality, and energy independence. However, there are also several challenges associated with the use of biodiesel including the compatibility of biodiesel with existing engine technologies and infrastructure as well as the cost of production, which can vary depending on factors such as location, climate, and competing uses for the feedstocks. Meanwhile, studies aimed at comprehensively assessing the impact of biodiesel on engine power, performance, and emissions are lacking. This becomes a major barrier to the dissemination of this potential energy source. Therefore, this study will provide a comprehensive view of the physicochemical properties of biodiesel that affect the performance and emission properties of the engine, as well as discuss the difficulties and opportunities of this potential fuel source.

AbstractThe objective of the present study is to scrutinize the influence of a binary blend of diesel–safflower oil biodiesel and ternary blends of diesel–biodiesel–pentanol on performance, emission and combustion characteristics of a diesel power generator. The test fuels were prepared on volume basis by splash blending and named as follows: B20, B20P5, B20P10, B20P15, and B20P20. The tests were carried out on a single-cylinder, four-stroke, naturally aspirated, and direct-injection diesel engine at four engine loads with a constant engine speed of 3000 rpm. According to the results, ternary blends vaguely reduced BTE while increased BSFC up to 13.90% as compared to diesel. In addition, an increase in pentanol concentration has a considerable effect on the decrease in NOX emissions. It is noted that the addition of pentanol to diesel–biodiesel blend caused to lower emissions (CO, HC, and smoke), whereas CO2 emission increased noticeably thanks to the more complete combustion due to the excess oxygen content. Reviewing combustion analysis results, pentanol addition led to decrease heat release rate and lower ignition delay up to 15% blend ratio compared to diesel. Based on the present study, pentanol can be evaluated as a promising type of higher alcohol for the compression ignition engines in the near future.Graphic abstract

In this study, the characteristics of diesel engines were tested with in-house produced mahua biodiesel blended with diesel and copper oxide nanoparticles (CuO NP) catalyst. The preliminary investigation used mahua biodiesel-diesel blends (M10, M20, and M30) among them M20 outperformed. Further M20 and CuO NP with concentrations of 25, 50, and 75 ppm are studied. Finally, the response surface methodology (RSM) was used to determine the appropriate NP concentration for M20. The findings showed that the blend of M20 with 60 ppm NP at 80% load had the highest desirability (0.9740), and the developed RSM model predicted engine responses with a mean absolute percentage error (MAPE) of 3.0962% to the confirmation test confirming the model’s accuracy. The optimized M20NP60 blend demonstrated superior combustion, performance and emission characteristics.

We conducted laboratory direct shear tests on two parallel coplanar intermittently jointed rock to investigate the effect of joint roughness and loading conditions on the shear behavior and acoustic emission characteristics. Experimental results show that the joint roughness, shear rate, and normal stress positively correlate with the peak shear strength of intermittently jointed rock. For intermittently jointed specimens with different roughness on both sides, the roughness significantly influences the mechanical properties of the jointed rock. The stress concentration at the loading end mainly affects the accumulative acoustic emission (AE) energy before the peak strength and the growth rate of the peak shear strength. In the residual stage, the influence of normal stress on the residual shear strength is greater than that of the shear rate. The damage rate of intermittently jointed rock shows an increasing trend with the increase in roughness, shear rate, and normal stress. However, the effect of roughness on the damage rate is less than that of the shear rate and normal stress.HighlightsThe influence of joint roughness and loading conditions on shear behavior and acoustic emission characteristics of two parallel coplanar intermittently jointed rock is studied by direct shear tests.The roughness, shear rate, and normal stress significantly affect the mechanical properties of intermittently jointed rock.Apply the acoustic emission (AE) to investigate the relationship between roughness, shear rate and normal stress on the AE signal.The effect of joint roughness, shear rate and normal stress on shear failure characteristics of rough discontinuous jointed rock mass were investigated.