• Energy Research
• 7. Clean energy close
• Chinese Academy of Sciences close

Abstract The coal gasification process is one of the main exergy destruction contributors in polygeneration systems and has considerable energy saving potential. In the present study, for improving the performance of the polygeneration system, the coal-steam gasification method was employed to integrate a novel methanol-electricity polygeneration system. The results indicated that the energy efficiency of the novel system was 63.3% with a chemical-to-power output ratio of 8.4, while the energy efficiency of the traditional system is 51.3% at the optimal unreacted syngas recycling ratio. Exergy analysis results revealed that the system exergy destruction in the coal–steam gasification process is 7.5% smaller than that in the GE gasification process, and eliminating the air separation unit can reduce the exergy destruction of the system by 4.3%. Additionally, the energy saving contributions of gasification process improvement and system integration were quantitatively evaluated. When the chemical-to-power output ratio increased from 1.9 to 11.9, the energy saving contributions of the system integration and gasification process improvement ranged from 9.8% to 15.1% and 11.9% to 12.9%, respectively.

AbstractThis article describes the application of cryogens in liquid fluid energy storage systems and compares liquid fluid energy storage systems with conventional compressed air energy storage systems. The study focuses on the thermodynamic characteristics of different cryogens used in liquid fluid energy storage systems. It is found that liquid fluid energy storage systems have competitive factors like high energy density and no geographical limitation. A comparative analysis is conducted to present the advantages and disadvantages of different cryogens. The results show that liquid fluid energy storage systems have a promising future in large scale energy storage.

AbstractFree cooling is one of the most potential ways of reducing the energy consumption of data centers. Thermosyphon has superior heat transferability thus it is suitable for application in free cooling. However, a separate thermosyphon free cooling system usually cannot provide sufficient cooling capacity in warm seasons. In order to overcome this weakness and avoid two sets of equipment, hybrid system of thermosyphon free cooling and vapor compression refrigeration for data centers has been developed by researchers. The cooling performance of this kind of system depends greatly on the climate outside therefore its applicability in different time and zones needs to be studied. In this paper, the climate data from five cities of different climate zones in China is collected. The performance model of the hybrid system is built up. Based on the climate data and performance model, the annual energy consumption is then calculated and compared with traditional air conditioner. The result shows that the energy-saving potential of the hybrid system varies in different climate zones, and when the mode switching temperature is relatively high, it is distinct in most climate zones of China.

Abstract The hydrothermal geothermal heating depends heavily on the existence of hot water reservoir and the shallow ground source heat pump occupies large area. Here a single well geothermal heating (SWGH) technology is shown, which does not depend on the existence of hot water reservoir. An experimental research on SWGH is carried out and a mathematical model describing the heat transfer through surrounding rock to well tube as well as inside the geothermal well is developed. The mathematical model validated by experimental data is then used to predict the performance of SWGH. It is found that the average extracted thermal output is respectively 448.49 and 413.63 kW in the first and tenth heating seasons. By changing the injection water temperature and velocity, SWGH system can meet the requirement of building heating load varying with the outdoor air temperature and adjust the imbalance of the extracted thermal output among different heating seasons. Understanding these will enable us to better apply SWGH technology.

Citrus wastes disposal is a problem faced by many juice plants due to high disposal costs. However, the citrus peel wastes (CPW) biomass, as bulk bioresources from the agro-industrial waste, is a good source of pectin. Present study aimed to utilize these CPW biomass by engineered yeast strain fermentation with an inexpensive method to produce oligogalacturonides (OGs). The results showed that the engineered yeast strain fermentation can produce significant amounts of OGs with the degree of polymerization ranged from 2 to 7 from the CPW bioresources. Under the optimized conditions using the response surface methodology, the best OGs yield were 26.1%. The present work is the first to use the engineered yeast strain for direct CPW biomass fermentation produced the OGs. We thereby paved a new way to utilize the pectin-rich bioresources.

In this paper, petroleum product (mainly petrol and diesel) consumption in the transportation sector of China is analyzed. This was based on the Bayesian linear regression theory and Markov Chain Monte Carlo method (MCMC), establishing a demand-forecast model of petrol and diesel consumption introduced into the analytical framework with explanatory variables of urbanization level, per capita GDP, turnover of passengers (freight) in aggregate (TPA, TFA), and civilian vehicle number (CVN) and explained variables of petrol and diesel consumption. Furthermore, we forecast the future consumer demand for oil products during “The 12th Five Year Plan” (2011–2015) based on the historical data covering from 1985 to 2009, finding that urbanization is the most sensitive factor, with a strong marginal effect on petrol and diesel consumption in this sector. From the viewpoint of prediction interval value, urbanization expresses the lower limit of the predicted results, and CVN the upper limit of the predicted results. Predicted value from other independent variables is in the range of predicted values which display a validation range and reference standard being much more credible for policy makers. Finally, a comparison between the predicted results from autoregressive integrated moving average models (ARIMA) and others is made to assess our task.

Abstract Accurate installed capacity forecasting can provide effective decision-making support for planning development strategies and establishing national electricity policies. First, considering the data limitation in quantity and accuracy, this paper proposes a multi-factor installed capacity forecasting framework combining the fuzzy time series method and support vector regression. Compared with four benchmark models, the proposed model shows advantages in installed capacity prediction. Second, the predictability dynamics of national installed capacity are explored from the perspective of country clusters. It is revealed that highly predictable countries usually obtain high forecasting accuracy with all forecasting models and are less sensitive to forecasting models. Using the k-means clustering method, this paper divides 136 sample countries into four categories according to the predictability. Third, based on the mean impact value analysis, this paper differentiates and ranks the importance of input variables on installed capacity development. The two most important factors influencing installed capacity are installed capacity development in the previous period and population. Overall, these results are of practical value to the operating decisions of electric power enterprises and the electricity plans of governments.

Abstract The development of the regional economy in China is unbalanced. Interregional "carbon leakage" and "carbon transfer" have a significant impact on the realization of carbon emission mitigation targets and the allocation of responsibility. Using China's interregional input-output tables and the corresponding carbon emission data for 2007 and 2010, this paper proposes an interregional Ghosh input-output model and estimates the amount of interprovincial carbon emission transfer from the supply-side perspective. We find that the main direction of supply-side carbon emission transfer is from resource-intensive provinces in the central and western regions to developed provinces in the eastern coastal regions. Further analysis shows that the transfer is mainly concentrated in the production and distribution of electricity and heat, nonmetallic mineral products, and basic metals, whose carbon emissions account for approximately 70% of all sectors’ carbon emissions. The differences between the supply side and the demand side of China's provinces are mainly reflected in the transfer out of carbon emissions.