Abstract

This study uses a coupled analysis framework to analyze energy consumption, socioeconomic drivers, and energy policies in Sichuan – the most populous province of China’s rapidly growing western region. The consumption of total energy and three key energy sources over 2002-2016 is decomposed using the logarithmic mean Divisia index method to identify underlying socioeconomic drivers, which are then coupled with a systematic energy policy review to analyze energy-policy interactions. Based on this analysis we suggest the means to optimize low-carbon development in the provincial five-year plan and to integrate the various policies published by different departments. Given the ineffectiveness in provincial economic restructuring for energy reduction, an energy trading system may be more effective and efficient. Over the coming decade, Sichuan also needs to accelerate its adoption of clean energy resources, in addition to further improvements in industrial production efficiency. The trends and policy implications that have been found for Sichuan are instructive for low-carbon development in China overall, and in its expansive western region especially.

Abstract

Solar lighting is considered as a promising technique, which has huge potential to energy conservation and help to relax the mood of residents in the building. However, existing solar lighting systems used a filter to allow only visible light (shortwave) entering buildings and all the other energy contained in the longwave of the solar was released into the surrounding air, which caused the low efficiency of solar energy utilization and the high costs due to such a filter. It is not beneficial for promoting the market application of solar lighting technology. In this paper, a solar lighting-heating dual-effect system was developed which uses a hollow filter that filled by nanofluids to separate the longwave and shortwave of the solar. Based on the spectral selectivity of nanofluids, this system can utilize solar energy in different wavelengths separately. A series of tests were conducted and results suggested that the solar energy utilization efficiency of this system was much higher than traditional solar lighting systems.

Abstract

Beijing has a relative long history in new energy vehicles promotion and achieves series achievements. However, traditional fuel vehicle is still heavily outnumbered. In this paper, we build a system dynamics model to forecast Beijing’s new energy vehicles ownership from 2017 to 2022. The simulation model also helps figure out how the policy, purchase price, psychology and usage affecting private new energy vehicles ownership.

Abstract

Carbon-dioxide mitigation in residential building sector (CMRBS) has become critical for China in achieving its emission mitigation goal in the “Post Paris” period with the growing demand for household energy service in residential buildings. This is the first paper to investigate the factors that can mitigate carbon-dioxide (CO2) intensity and further assess CMRBS in China based on a household scale via decomposition analysis. Here we show that: Three types of housing economic indicators and the final emission factor significantly contributed to the decrease in CO2 intensity in the residential building sector. In addition, the CMRBS from 2001–2016 was 1816.99 MtCO2, and the average mitigation intensity during this period was 266.12 kgCO2 · (household · year)-1. Furthermore, the energy-conservation and emission-mitigation strategy caused CMRBS to effectively increase and is the key to promoting a more significant emission mitigation in the future. Overall, this paper covers the CMRBS assessment gap in China, and the proposed assessment model can be regarded as a reference for other countries and cities for measuring the retrospective CO2 mitigation effect in residential buildings.

Abstract

The model order reduction (MOR) method is to convert a large system into a small system, which can reduce the amount of data calculation and save time and cost while maintaining a certain precision. In this paper, Krylov subspace, balanced truncation and Laguerre orthogonal polynomial MORs are developed to the numerical simulation of the heat transfer characteristics of ground heat exchangers under laminar and turbulent conditions. Firstly, the finite volume method is used to discretize the two-dimensional governing equation into an ordinary differential equation with respect to the pipe length direction. Then three MOR systems are established respectively. Finally, the specific examples are calculated. The results show that for a certain length of ground heat exchangers the total time taken by the balanced truncation method is much larger than that of the direct solution method, the Krylov subspace method and the Laguerre orthogonal polynomial method. The reasonable orders of the reduced order systems by the Krylov subspace method and the Laguerre orthogonal polynomial method are both 20. At this time, their solving time is all less than 11.3% (laminar flow) and 6.2% (turbulent flow) of the direct solution method. And the relative errors under the above conditions are all less than 10-7. As the length of the calculated pipe increases, the efficiency of the two MOR methods is more prominent.

Abstract

By means of the de Gennes model, the magnetocaloric characteristics of Gd-R (R= Dy, Er) alloys as well as Gd, which are materials for sustainable energy, are investigated and the related theoretical and experimental results are compared. The effects of Rdoped concentrations on the Curie temperature of Gd-R alloys are revealed. Furthermore, the dependencies of temperature of the heat capacities and adiabatic temperature changes of Gd, Gd0.95Dy0.05, and Gd0.95Er0.05 under 0 and 2T applied magnetic fields are analyzed and discussed. The calculated results shows that the Curie temperatures of these materials decrease with increasing R-doped concentration; the effect of magnetization/demagnetization on the adiabatic temperature change of Gd-R alloys is weak, but on the temperature at maximum adiabatic temperature change of Gd-R alloys is relatively evident. The calculation results in the present paper may provide some references for the parametric design of room temperature magnetic refrigerators that are energy conversion devices with environmental protection and energy saving.

Abstract

In our previous work, a novel isobaric adiabatic compressed air energy storage (IA-CAES) system has been proposed on the base of volatile fluid, while large amount of waste heat should be employed to offer the energy required in the evaporation, which may restrict its applications. In this work, a novel adiabatic compressed air energy storage (A-CAES) system is proposed which is also based on the volatile fluid while without using waste heat. Carbon dioxide (CO2) is selected as the volatile fluid. The stead-state mathematical model and thermodynamic laws are employed to evaluate proposed system. The calculation results show that our proposed A-CAES system has the same round trip efficiency (RTE) with conventional one, while more than 30% additional cooling energy can be obtained and the total exergy efficiency (TEE) improves more than 2%. For a given total power generation (4 MWh), the total volume of air storage unit in proposed A-CAES is only accounts for 60.97% of that in conventional A-CAES.

Abstract

The development of renewable energy is a huge opportunity and challenge in the energy field. As the ultimate energy source, solar energy is one of the most reliable energy sources among the renewable energies. Solar water splitting for hydrogen production is one of the most promising technologies of solar energy utilization, in recent decades. As an ideal clean energy source, hydrogen has made a significant breakthrough in transportation and storage technologies and hydrogen is also of great significance for applications such as chemical synthesis and energy storage. This paper reviews the basic methods and development of hydrogen production from solar water splitting, including photovoltaic, photoelectrochemical, and photothermal methods. In view of the photothermal method-solar thermochemical hydrogen production technology, this paper analyzes the thermodynamics, summarizes its future development perspectives. Furthermore, this paper also points out some new ideas for the realization of solar-thermal water splitting for hydrogen production.

Abstract

aking methane as fuel gas, nickel oxide as oxygen carrier and calcium oxide as carbon dioxide adsorbent, a solar-driven chemical-looping hydrogen production system was established and the hydrogen production performance of the system under different reaction conditions was explored. The results showed that, if the concentrating solar energy was used as the heat source of the fuel reactor, the ratio of nickel to methane was 2.25, the ratio of water to methane was 1, the temperature of the fuel reactor was between 450 and 600 oC, the pressure of the fuel reactor was at atmospheric pressure, and the ratio of calcium oxide to methane was 1, a better system performance could be achieved. The key process experiments are carried out in the honeycomb reactor. The results show that the separation of CO2 generated in the reaction process is and significant way to improve the efficiency of chemical looping hydrogen production. Using CaO to capture and separate CO2 in the reaction process could improve the effect of hydrogen production. Also, the huge energy consumption caused by gas separation could be avoided. This study presents a method for efficiently using low-temperature solar energy for hydrogen production.

Abstract

To recover the excess exhaust steam heat of the combined heat and power plant with high back‐pressure turbine (CHP‐HBP), a novel system integrated with the steam jet pump (SJP) was proposed in this study. Compared with the conventional system, the novel system remains the same power output and all the exhaust steam can be used for district heating (DH), leading to an improvement of the maximum heat capacity by 36.78MW. Meanwhile, the total exergy loss and standard coal consumption rate of the novel system are reduced by 3MW and 7.32 g/kWh, respectively. And the novel system also has better adaptability to the change of supply/return water temperatures.