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Abstract China's carbon emissions have been ranking first in the world. This study filled in the gaps in research, decomposed carbon intensity from the perspective of time, space and industry. A decoupling effort model based on factor decomposition models was constructed to analyze the driving factors of carbon emissions and economic decoupling, which builded a foundation for achieving sustainable economic development. Using the Logarithmic Mean Divisia Index method (LMDI), the paper measured the carbon emission intensity of 29 provinces and cities in China from 1998 to 2019, and decomposed the decoupling effect between GDP and carbon emission on the basis of factor decomposition by tapio. The results showed that: (1) Carbon intensity declined first, then rise lightly, and finally declined steadily. For the primary industry and the tertiary industry, the carbon intensity declined steadily, while the carbon intensity increased accordingly to the overall carbon intensity. In terms of spatial evolution, the regional differences between different provinces decreased correspondingly. (2) The cumulative contribution rates of these three effects, i.e., technological progress, industrial structure and regional scale were 106.3299%, −15.1486% and 8.8188%, respectively. There were obvious differences of these cumulative contribution rates of carbon intensity among different provinces. (3) From the perspective of industrial, technological progress effect is the largest contribution for carbon intensity in the secondary industry. The Industrial structure effect mainly affects the primary and tertiary industries; and no significant difference in regional scale effect. (4) The decoupling effect gradually improved, and technological progress has played an absolute leading role in promoting the decoupling effect. Based on the research results, the key policy recommendation are put forward as follows: (1) Further improve the technological level and support clean technology enterprises. (2) Promote industrial upgrading in backward industrial provinces (3) Promote regional assistance and the introduction of high-quality foreign investment.

Abstract Propane (C3H8) is being considered as an alternative refrigerant, besides being used as an alternative fuel, because of its low Global Warming Potential and zero Ozone Depletion Potential. Using blends of C3H8 with CO2 as refrigerants, diminishes the fire safety concerns in case of accidental leak of this flammable substance in refrigeration applications. This paper reports on the effects of CO2 on laminar burning speed and flame instability of C3H8/air blends at elevated temperatures and pressures. The flame structures were investigated in a Schlieren system. The laminar burning speeds of C3H8/CO2/air mixtures were measured in a spherical chamber and were fitted by a power-law mathematical correlation. The one-dimensional flame code from Cantera with kinetic model was also used to predict laminar burning speed. The high-speed photography showed that CO2 inhibits the flame instability because of its hydrodynamic and diffusional-thermal effects. Results showed that the laminar burning speed decreased with increasing CO2 mole fraction in the mixtures and that CO2 promotes the flame stability. The high temperature C3H8 oxidation was governed by the reaction of H + O 2 = O + OH . The effects of CO2 on laminar burning speed were mainly determined by the reaction of CO 2 + H = CO + OH and the high energy capacity (specific heat) of CO2.

Abstract Owing to the high penetration of renewable energy sources, power systems require more flexibility to respond to the fluctuation of variable renewable energy sources. However, flexibility provision by distributed energy resources (DERs) installed on the demand side is a cost-effective measure. In this study, we proposed a scheme that utilizes time-of-use (TOU) electricity rates as an incentive to encourage residential prosumers to provide more flexibility by controlling the DERs. In particular, we developed an energy management system model that applies model predictive control. The TOU rates were designed by an aggregator who traded with markets and prosumers. The DERs of residential prosumers were fuel cells with combined heat and power, CO2 heat pump water heaters, or batteries. Numerical simulations using measured energy demand and insolation data were performed to evaluate the performance of the developed model. According to the results, the developed model could integrate prediction errors and provide flexibility to the grid. Finally, the economies of the aggregator and prosumers were also evaluated.

In this paper, an experimental and numerical study on the flow evolution and energy extraction performance of a flapping-airfoil power generator is conducted, and wide ranges of motion parameters are considered. PIV (Particle image velocimetry) method is used for flow visualization around the flapping airfoil, and numerical simulations predicting the flow field and power generation process are also conducted and compared with the test results. It is found that the computed flow field basically agrees well with the experimental results, and the power generation ability of the power generator is validated. At a fixed plunging amplitude H0, both the decreasing reduced frequency k at a fixed pitching amplitude θ0, and the increasing θ0 at a fixed k lead to larger sizes of flow separation. For the flapping motion studied, both plunging contribution and pitching contribution play important roles in the energy extraction, which is very different from the traditionally imposed flapping profile. Besides, at a fixed k, the increasing H0 induces a slight increase in pitching contribution, and the increasing θ0 is beneficial to power generation enhancement. Moreover, the increasing H0 induces a notable increase in output power at relatively low k, while it has little effect on efficiency enhancement.

Abstract Distribution systems such as the Rural Electric Cooperatives (RECs) in the U.S. obtain power largely through purchases. Supply is often guaranteed through long-term contracts, and prices may be less sensitive in the short run to increases in fuel costs. The development of a model to capture some of the unique features of the RECs cost structures is discussed. The use of such a model in forecasting the growth of the cooperatives is presented; three scenarios of alternative assumptions regarding the growth of fuel prices are analyzed. Based on these scenarios, it is concluded that the annual load growths of RECs will range between 3.6 and 5.9% to the year 2000.