10 results
Search Results
2. Transition metal molybdenum (tungsten) carbide as catalysts for dry reforming of methane: A mini-review.
- Author
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Shanshan Duan and Yongkang Lv
- Subjects
- *
GREENHOUSE gas mitigation , *TRANSITION metal carbides , *STEAM reforming , *TRANSITION metals , *TRANSITION metal catalysts , *CATALYST supports - Abstract
Reducing greenhouse gas emissions or collecting and converting existing greenhouse gases has become a global concern. One of the most effective methods of utilizing CH4 and CO2 resources is the dry reforming of methane (DRM). Transition metal carbide catalysts have attracted wide attention because of their excellent catalysis performance and carbon deposition resistance. However, pure-phase carbides are easily oxidized and deactivated at atmospheric pressure in DRM reactions. There is a problem of poor dispersion (Mo2C 17 m² /g). Therefore, this paper summarizes the effects of adding active sites and supported carbides on the DRM reaction, discusses the role of active sites and supports in the catalyst, and introduces the different preparation methods of transition metal carbides. This paper also reviews the catalyst mechanism of transition metal carbides in DRM reactions. Nevertheless, the current research in this field needs to be deepened. Therefore, it is necessary to strengthen the exploration of various catalyst preparation methods and mechanisms, so as to realize future improvement in this field. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
3. Investigating the environmental Kuznets curve hypothesis for CO2 emissions in Nordic countries.
- Author
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Kar, Ashim Kumar
- Subjects
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KUZNETS curve , *CARBON dioxide , *ECONOMIC expansion , *CROSS-sectional method , *HETEROGENEITY - Abstract
This paper examines the environmental Kuznets curve (EKC) hypothesis in Nordic countries (Denmark, Finland, Iceland, Norway and Sweden) over the period 1981–2018. The link between economic growth and carbon dioxide (CO2) emissions is analysed. The study includes causality analysis and controls for cross-sectional dependence (CSD), slope heterogeneity, stationarity and cointegration patterns. Estimations validate the EKC hypothesis for Denmark and Iceland, but not for Norway and Sweden. Finland data show no significantly visible trend. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
4. Effects of regional freight structure and energy intensity on CO2 emission of transport—a case study in Yangtze River Delta.
- Author
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Yin, Chuanzhong, Wang, Chenjiahui, Wang, Qing, and Ge, Ying-en
- Subjects
- *
CARBON emissions , *CARBON dioxide , *TRANSPORTATION industry , *INDEPENDENT variables - Abstract
Taking the Yangtze River Delta (YRD) of China as the research area, this paper studies the influence of freight structure adjustment and energy intensity on carbon dioxide (CO2) emission from the transportation industry. Sample data from 1990 to 2019 are selected, and co-integration analysis is performed using three independent variables: energy intensity, turnover ratio of railway to highway (R/H), and turnover ratio of railway to waterway (R/W). Then, an autoregressive distribution lag-error correction model (ARDL-ECM) is established to estimate the long-run and short-run relationships among the variables through unit root test, autoregressive distributed lag (ARDL) boundary test, and Granger test. The results show that in the long run, the growth of energy intensity leads to the long-term growth of CO2 emission in the transportation sector of the YRD, and R/W and R/H have a suppressive effect on CO2 emission. Granger causality indicates that there is a bidirectional causal relationship between energy intensity and CO2 emission. This work can be a reference for government departments to formulate policies related to carbon emissions in the transportation industry. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
5. Towards an energy management system based on a multi-agent architecture and LSTM networks.
- Author
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Bouziane, Seif Eddine and Khadir, Mohamed Tarek
- Subjects
- *
ENERGY management , *RENEWABLE energy sources , *MULTIAGENT systems , *HYBRID systems , *CLEAN energy , *ENERGY consumption - Abstract
Energy generation and pollutant emissions are two faces of the same coin, as the current energy sources i.e., fossil energy, are still considered to be major sources of greenhouse gases (GHG). Therefore, shifting to cleaner energy sources imposes itself as an inevitable solution to reduce this environmental cost. In this paper, a hybrid system based on the multi-agent approach and Long Short-Term Memory (LSTM) neural networks to forecast the energy production and its carbon dioxide (CO2) emissions and simulate the potential emission reduction in case of switching to renewable energy sources is presented. The proposed system's architecture consists of combining LSTM models with the agent-based technology, where multiple LSTM forecasting models were trained to forecast the production of each type of the studied energies and then estimate the equivalent emitted CO2 and calculate the influence of the renewable energy inputs on the carbon emissions and the fossil fuels consumption. The simulation process consists of two phases: firstly, each forecasting agent uses a specific LSTM model to forecast short-term energy production. Secondly, these agents send the forecasted values to the coordination agent who is responsible for calculating the total CO2 emissions and the benefits of the renewable energy inputs. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
6. Study on separation of CO2 condensation from natural gas based on cellular automaton method.
- Author
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Haiqin Wang, Qi Lu, Zubin Zhang, Jianyang Lin, and Qishen Wu
- Subjects
- *
CELLULAR automata , *NATURAL gas , *SUPERSATURATION , *CONDENSATION , *MOLE fraction , *PHASE transitions , *CARBON dioxide - Abstract
The CO2-containing natural gas is increasing, and there is an urgent need for green treatment of natural gas containing CO2 to realize the utilization of natural gas. Conventional natural gas decarbonization methods have drawbacks such as non-environmental friendliness, and the low-temperature condensation separation of carbon dioxide (snowing-separation) method as a green method of carbon capture is proposed in this paper. Aiming at the characteristics of CO2 condensation in the snowing-separation process, the growth process of CO2 crystals is obtained by simulation using the CA (Cellular Automata) method and finds that the effect of supersaturation on the growth of CO2 crystals is exponential. The snowing-separation process at .5 MPa is analyzed, and it is found that the condensation range is 158.51 K–173.86 K, the upper limit of CO2 mole fraction in natural gas is 10.1%, and the minimum separation time is 8.65 × 10−8s. Analyzing the influencing factors of CO2 separation efficiency, combining the simulation results with the experimental results, the maximum relative error is 13.93%, which can better predict the snowingseparation technology of CO2 in natural gas, and then promote the development of efficient low-temperature carbon capture process. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
7. The undesirable impact of China's "national sustainable development plan of resource-based cities" on CO2 intensity.
- Author
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Dong, Daxin and Wang, Jiaxin
- Subjects
CITIES & towns ,CARBON dioxide mitigation ,SUSTAINABLE development ,SUSTAINABLE urban development ,REGIONAL development ,CARBON dioxide - Abstract
China's numerous resource-based cities have confronted severe environmental and economic problems, which were substantial impediments to the regional sustainable development. In 2013, China started to implement its 'National Sustainable Development Plan of Resource-Based Cities', in order to transform the previous development patterns. This study employs the difference-in-differences (DID) method to evaluate the policy's impact on the city-level carbon dioxide (CO
2 ) emission intensity. CO2 intensity is defined as the scale of CO2 emitted per unit of GDP. The research sample covers 326 Chinese cities during 2008—2017. Research results indicate that the policy significantly increased the CO2 intensity in resource-based cities. Moreover, it is found that the policy dampened resource-based cities' innovation levels and these cities did not strengthen their environmental regulations, which can be provided as the explanations of why the policy effect on carbon intensity was positive. Furthermore, this study reports the discrepancies in policy effects when cities have different development stages, spatial locations and marketization levels. Overall, this research discovers an undesirable policy effect. More actions should be taken to reduce the carbon intensity during the structural transformation in resource-based cities. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
8. Solar energy-assisted CCHP cycles for dairy applications in rural sector with effect assessment of reheating on novel CO2 working fluid.
- Author
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Vutukuru, Ravindra, Giri, Jayant, Amir, Mohammad, Chadge, Rajkumar, and Sathish, T.
- Subjects
ELECTRIC power ,WORKING fluids ,PASTEURIZATION of milk ,CARBON dioxide ,DAIRY farms ,DAIRY processing - Abstract
This study investigates two configurations of novel solar energy-assisted combined cooling, heating and power (CCHP) systems suitable for the dairy industry. The system uses carbon dioxide (CO
2 ) as the working fluid. The cooling and heating outputs were used for the simultaneous chilling and pasteurization of milk. The electrical power produced in the turbine is used to run the compressor and cater to the miscellaneous electrical demands of the dairy farm, thereby achieving grid independence. A detailed thermodynamic analysis was performed on the two configurations (with and without reheating) to identify the impact of various independent parameters on system performance. In addition, an irreversibility analysis was performed on the components in both configurations to obtain an idea of the losses occurring in the system. It is observed that the addition of the reheater provides a better specific net power output by approximately 4% over a variation of 6000 kPa in the cycle maximum pressure. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
9. New measurement of the diffusion of carbon dioxide on non-porous amorphous solid water.
- Author
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He, Jiao, Pérez Rickert, Paula Caroline, Suhasaria, Tushar, Sohier, Orianne, Bäcker, Tia, Demertzi, Dimitra, Vidali, Gianfranco, and Henning, Thomas K.
- Subjects
DIFFUSION measurements ,AMORPHOUS substances ,CARBON dioxide ,INTERSTELLAR molecules ,ICE sheets - Abstract
The diffusion of molecules on interstellar grain surfaces is one of the most important driving forces for the molecular complexity in the interstellar medium. Due to the lack of laboratory measurements, astrochemical modeling of grain surface processes usually assumes a constant ratio between the diffusion energy barrier and the desorption energy. This over-simplification inevitably causes large uncertainty in model predictions. We present a new measurement of the diffusion of CO $ _2 $ 2 molecules on the surface of non-porous amorphous solid water (np-ASW), an analog of the ice mantle that covers cosmic dust grains. A small coverage of CO $ _2 $ 2 was deposited onto an np-ASW surface at 40 K, the subsequent warming of the ice activated the diffusion of CO $ _2 $ 2 molecules, and a transition from isolated CO $ _2 $ 2 to CO $ _2 $ 2 clusters was seen in the infrared spectra. To obtain the diffusion energy barrier and pre-exponential factor simultaneously, a set of isothermal experiments were carried out. The values for the diffusion energy barrier and pre-exponential factor were found to be $ 1300\pm 110 $ 1300 ± 110 K and $ 10^{7.6\pm 0.8} $ 10 7.6 ± 0.8 s $ ^{-1} $ − 1 . A comparison with prior laboratory measurements on diffusion is discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
10. The Effect of Denim Fabric as a Feedstock in Large Scale Composting of Manure/Bedding and Food Scraps.
- Author
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Schwarz, Mary, Alwala, Wendy, Perju, Antonia, Bonhotal, Jean, Frey, Margaret, Pires, Steven, Ankeny, Mary, and Daystar, Jesse
- Subjects
COMPOSTING ,DENIM ,MANURES ,CIRCULAR economy ,FEEDSTOCK ,CARBON dioxide ,ECOLOGICAL impact - Abstract
This study provides scientific evidence for the process of denim biodegradation and the viability of including denim waste in large scale composting facility feedstock streams. Fourteen samples of denim using different dyes and dye processes provided by Cotton Incorporated as well as worn and unworn whole and scrap denim fabric were incorporated into a manure/bedding and food scrap windrow at the Cornell composting facility and in a bench scale laboratory trial. Grab samples of compost were analyzed for compost parameters, metals and PFAS. Visual observation of decomposition of denim showed polyester blended denim degraded at a slower rate than non-blended denim. However, after four months of hot composting, most of the denim had decomposed into organic matter, leaving only small pieces of the polyester thread, labels, and pockets. Bench scale degradation, tracked by carbon dioxide evolution and mass difference showed significant degradation at the macro and microscopic levels at day 75. Composting denim fabric has no detrimental effect on the composting process, nor on the quality of the resulting compost and thus can be used to grow cotton and other crops, reducing the carbon footprint, and contributing to the circular economy. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
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