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Abstract: This paper is based on dynamic optimization methodology to investigate the economic energy efficiency issues in developing countries. The paper introduces some definitions about energy efficiency both in economics and physics, and establishes a quantitative way for measuring the economic energy efficiency. The linkage between economic energy efficiency, energy consumption and other macroeconomic variables is demonstrated primarily. Using the methodology of dynamic optimization, a maximum problem of economic energy efficiency over time, which is subjected to the extended Solow growth model and instantaneous investment rate, is modelled. In this model, the energy consumption is set as a control variable and the capital is regarded as a state variable. The analytic solutions can be derived and the diagrammatic analysis provides saddle-point equilibrium. A numerical simulation based on China is also presented; meanwhile, the optimal paths of investment and energy consumption can be drawn. The dynamic optimization encourages governments in developing countries to pursue higher economic energy efficiency by controlling the energy consumption and regulating the investment state as it can conserve energy without influencing the achievement of steady state in terms of Solow model. If that, a sustainable development will be achieved. [Copyright &y& Elsevier]

Abstract: The three-dimensional energy resources demand-supply system is established for two regions of China, in which determination of unknown parameters is significant for the real energy resources demand-supply system. In this paper, based on Shanghai’s energy statistic data (1999–2005), the parameters of the energy resources demand-supply system can be identified by using the neural network method, and an energy resources demand-supply system reflecting the real energy resources demand-supply relationship in Shanghai is obtained. The dynamical behavior of this system is also analyzed. Theoretical analysis and numerical simulation indicate that the obtained energy resources demand-supply system has the capacity of self-regulation and demonstrates a steady state. Finally, to ensure the steady development of the energy resources demand-supply system, corresponding measures are proposed. [Copyright &y& Elsevier]

Abstract: China is a large developing country with high carbon intensity. It is likely that China will have to face the challenge of CBTA (carbon motivated border tax adjustments) in future. Meanwhile, CBTA would create price gap between CBTA users and target countries, and change the competitiveness of different producers. Under such circumstances, this paper seeks to contribute to the debate on CBTA by focusing on the potential impacts of CBTA on different regions of China from a perspective of competitiveness. We adopt two geographical divides in China (eastern–central–western zones, high-trade-openness to low-trade-openness regions), and simulate the potential impacts across regions through a general equilibrium model. Our simulation results show that CBTA would affect competitiveness of different producers, their comparative advantages, relative trade shares, outputs and emissions. CBTA would induce structure change of the economy, and result in a shift of industrial output toward non-industrial output. There are significant differences in the effects of CBTA among different regions in China. CBTA would result in a relocation of outputs across regions in China. Therefore, CBTA would also have impact on China’s regional development policy. [Copyright &y& Elsevier]

In data centers, a large number of IT sever racks with different heat dissipation rates are arranged in multiple rows, leading to much higher per-unit heat release and therefore more uneven temperature distribution than in general buildings. This paper chooses a small-scale data center located in China to analyze the thermal environment for the operation of these critical equipments. The wind speed and temperature in the data center were measured, and a corresponding computer room model was established via computational fluid dynamics (CFD) simulation software. Based on it, the characteristics of flow field and temperature field of the data center were analyzed. The optimization methods for problem of uneven temperature distribution and chaotic air supply in the data center were proposed and verified by evaluation index. Furthermore, the return temperature index(RHI) increased from 0.918 to 0.93, the return heat index(RTI) increased from 0.222 to 0.342. • The thermal environment of a small-scale data center in Wuhan, China was measured. • The data center model was established via numerical simulation software. • The optimized schemes for the thermal environment in the data center were proposed. • Optimization of data center can provide reference for construction and operation. [ABSTRACT FROM AUTHOR]

In northern China, transmission power system and district heating systems (DHSs) are directly connected by large-capacity combined heat and power (CHP) units, which composes the wide-area integrated power and heat system (IPHS). For better wind power accommodation, it is crucial to explore the operational flexibility of each local DHS in the wide-area IPHS. This paper investigates the available electric flexibility from the DHS through the CHP units and the heat-to-power devices. A flexibility region method is proposed to accurately formulate the DHS's flexibility in terms of power capacity and energy capacity, with a special emphasis on the temporal-coupling feature which is usually oversimplified in the existing studies. Then, solving algorithm is discussed to construct the polytope-form flexibility region, which provides an explicit and concise description of the electric flexibility from the DHS. Flexibility indicators are also developed for flexibility potential quantification. Further, a practical IPHS dispatch scheme is designed, which performs the wide-area power dispatch and the local-area heat dispatch hierarchically. Numerical simulation demonstrates the effectiveness of the flexibility region method in assessing the DHS's electric flexibility and performing the IPHS dispatch, as well as the benefit of coordinating the flexibility from multiple DHSs for wide-area wind power accommodation. • The temporal-coupling feature of the heating system's flexibility is illustrated. • Flexibility region is proposed to model the electric flexibility of heating system. • Indicators are proposed to assess heating system's flexibility potential. • A wide-area integrated heat and power dispatch scheme is developed hierarchically. • Heating system provides considerable time-series flexibility for power system. [ABSTRACT FROM AUTHOR]