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China has set a goal to achieve peak CO2 emissions before 2030 and carbon neutrality by 2060. To achieve the goals of carbon peak and carbon neutrality, China needs to address the challenge of the large and still growing CO2 emission base. This paper investigated the energy consumption and CO2 emission in Beijing from 2020–2035 based on the energy elasticity coefficient and contribution value of the sub-energy increment (CVSI) method. Beijing is one of the first cities in China to propose the "carbon peak" target as of 2020. From 2020 Beijing will strive to achieve the goal of carbon neutrality. The results show that in 2035 the CO2 emission in Beijing may drop to 50% of 2020. This decline would be affected by economic growth, energy efficiency and the proportion of renewable energy use. Beijing's energy supply mainly comes from outside the region. Therefore, for Beijing, in addition to increasing the proportion of renewable energy sources outside the region, its own energy acceptance also needs to be strengthened, including strengthening energy storage construction, actively researching and promoting carbon capture and utilization of gas-fired units, which are effective ways to achieve carbon neutrality target. [ABSTRACT FROM AUTHOR]

This study focuses on analyzing the provincial CO2 emission efficiency of China using data on energy consumption and carbon emissions from 2013 to 2019. Specifically, the game cross-equilibrium efficient frontier data envelopment analysis (DEA) approach, consisting of a game cross-efficiency model and a DEA fixed-sum output model, was proposed. In this method, CO2 is considered a fixed-sum undesirable output, and the decision-making units (DMUs) affect each other to achieve the efficiency result. The results show that: (1) CO2 emissions efficiency varied significantly between provinces during the study period, with Beijing performing the best and Ningxia the worst. (2) The overall national average CO2 emission efficiency showed a slow increasing trend over time. The eastern region performed best, followed by the northeastern, central, and western regions. (3) By comparing the existing DEA fixed-sum output methods, the CO2 efficiency obtained by our method, considering the DMU game relationship, is more acceptable. Based on these results, several policies and improvements were recommended to the provinces, such as reducing energy utilization in high-carbon emission industries. [ABSTRACT FROM AUTHOR]

In light of reducing train operation energy consumption while maintaining the passenger service level for creating sustainable urban rail transit systems, we address a non-parallel train timetabling problem considering regenerative braking energy utilization and the non-parallel operation of multiple trains on a metro line via a newly proposed multi-objective timetable (MOT) optimization model and an evolutionary algorithm based on NSGA-II. The optimization objectives of the MOT model are to find satisfactory energy-saving timetables on the Pareto frontier by minimizing the total travel time of passengers and minimizing the net energy consumption of trains. An improved multi-objective evolutionary algorithm based on NSGA-II is constructed to generate the optimal arrival and departure times at each station for each train running in a non-parallel operation mode. This study tests the feasibility of the proposed optimization method via an empirical case using the data collected from the Yizhuang Line of the Beijing metro systems in China. The simulation results show that the proposed optimization method satisfies both the energy utilization and passenger service levels along a Pareto front. The MOT improves the overall effectiveness of regenerative braking energy utilization by 29.88% in comparison with the original timetable; it reduces the net operation energy consumption by 44.86% relative to the travel-oriented timetable (TOT); and it reduces the total passenger travel time by 27.18% compared with the energy-oriented timetable (EOT). [ABSTRACT FROM AUTHOR]

In recent years, China has been vigorously carrying out the construction and development of a sponge city. To prove that the material and energy consumption involved in the implementation of a sponge city is much less than that of the integrated urban drainage system (IUDS) in addition to saved energy and reduced carbon in the sponge city, it was important to calculate the corresponding carbon source and sink and analyze its key influence factors. The emission factor method was used to calculate carbon emissions. In view of this, based on the Intergovernmental Panel on Climate Change (IPCC) guidelines and life cycle assessment (LCA), this research established a systematic accounting method for carbon emissions from the IUDS and the sponge city, which focused on improving the calculation method of the carbon sink stage. A case study was conducted in Beijing, China, and the carbon emission reduction effect of the construction of the sponge city was discussed. The results showed that the carbon emission reduction potential (CRP) of sponge facilities in this project for 50 years was 612.45 tons of CO2 equivalent after the renovation. Compared with IUDS, sponge city construction had a positive effect on carbon emission reduction and reduced carbon emissions by 87.08% on average. For the IUDS and the sponge city, the stormwater pipe network had the largest contribution of carbon emission, and its material, transportation, pipeline laying, and maintenance of stormwater pipe networks had important influences. Morris global analysis method was used to analyze the sensitivity of LCA results and obtained that the influence degree of sensitivity factors on carbon emissions in the life cycle was in the order of annual rainfall > carbon sequestration rate of green space > high-density polyethylene (HDPE) > transport distance > fertilization and insecticide. This study can provide a positive contribution to the construction of a sponge city and planning the low-carbon development of the city in the future in China. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes the development of a forecasting model, named the emergy-based urban dynamic model capable of accurately simulating the observed resource consumption, economic growth and environmental impact of Beijing. This model differs from previous urban emergy models by monitoring the negative effects to human well-being and ecosystem integrity in the developing urban system. A fresh perspective focuses on urban comprehensive performance linking such impacts to a supply-side environmental cost evaluation (including ecological service supply, ecological and economic losses and investment for treatment). In this introductory paper, we present the conceptual considerations of the most important components of the emergy-based urban dynamic model: the urban assets, lands, capitals, population, water resources, economic and environmental loss. Each subsystem in this model will enrich the feedback dynamics, policy levers and post-scenario analyses. Statistical Information and calibration are also considered in this dynamic emergy accounting. This study advances the temporal dynamic principles of emergy accounting through integrating upstream and downstream evaluation methods to quantify the environmental impact by addressing specific damages to human health and ecosystem''s integrity and by linking such impacts to a supply-side environmental cost evaluation. [Copyright &y& Elsevier]

The establishment of low-carbon cities has been suggested all over the World, since cities are key drivers of energy usage and the associated carbon emissions. This paper presents a scenario analysis of future energy consumption and carbon emissions for the city of Beijing. The Long-range Energy Alternatives Planning (LEAP) model is used to simulate a range of pathways and to analyze how these would change energy consumption and carbon emissions from 2007 to 2030. Three scenarios have been designed to describe future energy strategies in relation to the development of Beijing city, namely a reference scenario (RS), control scenario (CS), and integrated scenario (IS). The results show that under the IS the total energy demand in Beijing is expected to reach 88.61 million tonnes coal equivalent (Mtce) by 2030 (59.32 Mtce in 2007), 55.82% and 32.72% lower than the values under the RS and the CS, respectively. The total carbon emissions in 2030 under the IS, although higher than the 2007 level, will be 62.22% and 40.27% lower than under the RS and the CS, respectively, with emissions peaking in 2026 and declining afterwards. In terms of the potential for reduction of energy consumption and carbon emissions, the industrial sector will continue to act as the largest contributor under the IS and CS compared with the RS, while the building and transport sectors are identified as promising fields for achieving effective control of energy consumption and carbon emissions over the next two decades. The calculation results show that an integrated package of measures is the most effective in terms of energy savings and carbon emissions mitigation, although it also faces the largest challenge to achieve the related targets. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we give an overview of the situation of CO2 emissions in both Beijing and Tokyo and discuss and compare the causes for their emission changes according to decomposition based on both social activities and fuel varieties. We find that in order to enjoy a sustainable development, Beijing needs to learn from Tokyo especially in energy consumption area. At the end of the paper, the cooperation between these two metropolises is summarized. [Copyright &y& Elsevier]

Abstract: Energy consumption is a technical issue or a spatial structure issue? Aim of this paper is to study the impact of population density and energy consuming density to space together on energy consuming with urban districts of Beijing. The author of this paper puts two kinds of factors including economic and technological ones, and urban space context factors with energy consuming together into a model. LMDI method will be employed to do the analysis. It is concluded that non-economic and non-technological factors were also significant to reduce energy consumption. Even population density did not contribute to reduction of energy consuming, when it was combined with energy consuming density to space together, the contribution was efficient. It indicates that compacted urban space with low-carbon city is the most efficient way to reduce energy consuming in urban areas. © 2011 Published by Elsevier Ltd. Selection and peer-review under responsibility of RIUDS [Copyright &y& Elsevier]

The impact of environmental motivations on the individual's decisions regarding investments in energy efficiency and the adoption of energy-saving habits are analyzed for a representative sample of Chinese inhabitants from the larger Beijing area, replicating a comparative study on Western Europe. For the considered type of energy efficiency investments and daily energy-saving activities similarities and discrepancies between the two regions are discussed in regard to their sociocultural background as well as governmental regulations. The study provides empirical evidence that for Chinese environmental issues if all only play a tertiary role after monetary and regulatory incentives. The findings could suggest that in China policy programs aimed at raising environmental awareness and forming pro-environmental motivations might not lead to an increase in energy efficiency investments and daily energy-saving activities and the Chinese government's interests in this regard might be better served by implementing corresponding incentives via regulations. In the long-term. However, social peer pressure might affect a change in the Chinese mentality. [ABSTRACT FROM AUTHOR]

Abstract: In order to further study the realization of carbon intensity target, find the key influencing factors of CO2 emissions, and explore the path of developing low-carbon economy, this paper empirically studied the influences of urbanization level, economic level, industry proportion, tertiary industry proportion, energy intensity and R&D output on CO2 emissions in Beijing using improved STIRPAT (stochastic impacts by regression on population, affluence and technology) model. The model is examined using partial least square regression. Results show that urbanization level, economic level and industry proportion positively influence the CO2 emissions, while tertiary industry proportion, energy intensity and R&D output negatively do. Urbanization level is the main driving factor of CO2 emissions, and tertiary industry proportion is the main inhibiting factor. In addition, along with the growth of per capita GDP, the increase of CO2 emissions does not follow the Environmental Kuznets Curve model. Based on these empirical findings and the specific circumstances of Beijing, we provide some policy recommendations on how to reduce carbon intensity. Beijing should pay more attention to tertiary industry and residential energy consumption for carbon emission reduction. It is necessary to establish a comprehensive evaluation index of social development. Investing more capital on carbon emission reduction science and technology, and promoting R&D output is also an efficient way to reduce CO2 emissions. [Copyright &y& Elsevier]

Abstract: External wall insulation plays an important role in building energy consumption through affecting cooling and heating energy uses. In this paper, a study on the effects of external wall insulation thickness on annual cooling and heating energy uses under different Chinese climates is reported. Firstly, two indexes: Energy Gain Ratio (EGR) and Relative Variation Ratio (RVR) of the sum of annual cooling and heating energy uses, to assess the effects of external wall insulation thickness on energy saving potential are introduced. Secondly, a model space having four different exterior zones facing four different orientations in an office building is presented and the settings of the model space described. Lastly, the simulated annual cooling and heating energy uses for the four different exterior zones at different external wall insulation thicknesses under three different climates in China, Guangzhou, Shanghai and Beijing, are reported. The results suggested that energy saving was significant by increasing the external wall insulation thickness in exterior zones facing all orientations under Beijing’s climate, since the heating energy use was dominant and can be reduced remarkably with the increase in insulation thickness. Under Shanghai’s climate, increasing external wall insulation thickness to over 26mm would not reduce the sum of annual heating and cooling energy uses in the south-facing exterior zone, but would help save energy in exterior zones facing the other three orientations. For all exterior zones under Guangzhou’s climate, it was, however, hardly possible to reduce the sum of annual heating and cooling energy uses by increasing the external wall insulation thickness. [Copyright &y& Elsevier]

Abstract: A novel solar building cooling heating and power (BCHP) system driven by solar energy and natural gas is proposed in this paper. The performance of the presented system is greatly dependent upon the operation strategy. The primary energy consumption (PEC) and pollutant emissions of the solar BCHP system in following the electricity loads (FEL) and following the thermal loads (FTL) operation strategies are estimated based on life cycle assessment (LCA). Furthermore, three most important energy-related environment problems and human health issues, global warming, acid precipitation and respiratory effects, are considered to assess the environmental impacts of the system. In order to evaluate the comprehensive benefits achieved by the solar BCHP system in different operation modes, grey relation theory is employed to integrate the energetic benefits with environmental performances. Finally, a numerical case of the solar BCHP system for a commercial office building in Beijing, China is applied to compare the integrated performance in the FEL operation strategy with that of the FTL operation strategy. The results indicate that the energy saving and pollutant emissions reduction potentials of the FTL operation mode are the better than that of the FEL mode. [Copyright &y& Elsevier]

Abstract: The groundwater heat pump (GWHP) system utilizes groundwater as alternative renewable and clean energy source for space heating and cooling, which is an open-loop system that withdraws water from a production well, passes it through a heat exchanger and discharges the water into an injection well. By utilizing the relatively stable temperature of groundwater, GWHP system can work with a higher coefficient of performance. It is necessary to evaluate the aquifer capacity for the proper design and application of GWHP. In this paper, a numerical method of underground heat transfer, energy balance method and thermal storage method were presented to calculate the load capacity of a unit area of shallow aquifer. The model results indicate that the numerical method, which is based on performance efficiency of groundwater heat pump, reflects the behavior of groundwater pumping and recharging processes, and better than energy balance method and thermal storage method, additionally it has the advantages of energy saving and environmental protect. The capacity is positively related to aquifer thickness. The final results show that it is easy for ground water recharging in alluvial and pluvial fan located at the piedmont, while load capacity is relatively smaller. In contrast, it is difficult for groundwater recharging in south-east plain where a larger load capacity is obtained. [Copyright &y& Elsevier]

Abstract: Operation mode of combined cooling heating and power (CCHP) system determines its energetic and environmental performances. This paper analyzes the energy flows of CCHP system and separated production (SP) system. The fuel energy consumptions of CCHP system following electrical demand management (EDM) and thermal demand management (TDM) are deduced respectively. Three indicators: primary energy saving, exergy efficiency and CO2 emission reduction, are employed to evaluate the performances of CCHP system for a commercial building in Beijing, China. The feasibility analysis shows that the performance of CCHP system is strictly dependent upon building energy demands. The selection of CCHP operation modes is systemically based on building loads, CCHP system and local SP system. The calculation results conclude that CCHP system in winter under EDM achieves more benefits than in summer. The sensitivity discussion indicates that the coefficient of performance for cooling and the efficiency of electricity generation are the most sensitive variables to the energetic and environmental performances of CCHP system. [Copyright &y& Elsevier]

Abstract: In the near future, energy conservation and pollution reduction became two of the most significant factors in economic development and social circulate. For analyzing the issue, several models were applied involving the fields of mathematical optimization, economics theory, dynamics model and industrial management. Specifically, they are MARKAL model, Input-Output model, LEAP model and Systemic Dynamics model. In the paper, a collaborative distributed database and an integrated simulation were developed for the Economics-Energy-Environment (3E) system, especially four models were firstly synthesize in a unique way which achieve securities economically, environmentally, as well as in a sense of energy source. The integrated matrix inherits the advantages of all methodologies mentioned above. At last, a flawless integration of the 3E-Safety system was presented and applied in a practical manner in the case of low-carbon development. [Copyright &y& Elsevier]

Abstract: Gas-to-liquids (GTL) as an alternative to diesel is considered to be one of the technical options to reduce petroleum consumption in the on-road transportation sector. Between May and August 2007, a joint demonstration program by Tsinghua University, Beijing Transit, Cummins Corporation and Shell Corporation was carried out in Beijing. The program focused on the supply systems and vehicle use of GTL fuel. The demonstration fleet was formed by four transit buses fueled with GTL and four with diesel. It was demonstrated that GTL has good compatibility with diesel in terms of fuel supply system and vehicle use. This paper compares the energy consumption and GHG emissions of diesel and GTL fuel supply chains by life cycle analysis based on demonstration results. The results indicate GTL’s large range (reported 54–70%) in synthesis efficiency, as the key factor in determining energy consumption and GHG emissions within the GTL fuel supply chain. For the probable case (GTL synthesis efficiency: 65%), the life cycle energy consumption and GHG emissions of GTL fuel are 42.5% and 12.6% higher than that of diesel. For two sensitivity analysis cases (GTL synthesis efficiency: 54% and70%), energy consumptions are 74.2% and 31.2% higher and GHG emissions are 27.3% and 7.4% higher than that of the diesel fuel supply chain. If the efficiency of the GTL synthesis process is improved to 75%, then the GHG emissions level of the GTL fuel supply chain can be reduced to the same level as the diesel fuel supply chain. [Copyright &y& Elsevier]

Electrifying transportation in the form of the large-scale development of electric vehicles (EVs) plays a pivotal role in reducing urban atmospheric pollution and alleviating fossil fuel dependence. However, the rising scale of EV deployment is exposing problems that were previously hidden in small-scale EV applications, and the lack of large-scale EV operating data deters relevant explorations. Here, we report several issues related to the battery utilization and energy consumption of urban-scale EVs by connecting three unique datasets of real-world operating states of over 3 million Chinese EVs, operational data, and vehicle feature data. Meanwhile, by incorporating climatic data and EV data outside China, we extend our models to several metropolitan areas worldwide. We find that blindly increasing the battery energy of urban EVs could be detrimental to sustainable development. The impact of changes in the energy consumption of EVs would be exacerbated in large-scale EV utilization, especially during seasonal shifts. For instance, even with a constant monthly driving demand, the average energy consumption of Beijing light-duty EVs would change by up to 21% during winter-spring shifts. Our results may also prove useful for research on battery resources, urban power supply, environmental impacts, and policymaking. [ABSTRACT FROM AUTHOR]

Megacities are places with intensive human activity and energy consumption. To reduce air pollution, many megacities have relocated energy supplies and polluted industries to their outer regions. However, regional transport then becomes an important source of air pollution in megacities. To improve air quality before and during the 2008 Beijing Olympics, a wide range of control strategies were implemented, including the relocation of polluting industries. High sulfur dioxide (SO2) concentrations were occasionally observed during this period. Potential sources from southern regions of Beijing were indicated by backward trajectories model and urban/rural stationary measurements, but direct evidence was lacking. Here we used a mobile laboratory to characterize the spatial distribution and regional transport of SO2 to Beijing during the Campaign for Air Quality Research in Beijing and the Surrounding Region (CAREBEIJING)-2008. Among the five days chosen for the case studies during the Olympic air pollution control period, four had high SO2 concentrations (6, 20 August and 3, 4 September 2008) while one had low SO2 concentration (11 September 2008). The average values of SO2 during the low SO2 concentration day were 3.9 ppb, much lower than during the high concentration days (7.8 ppb). This result implied an impact by regional transport from outside Beijing. During these days, we captured transport events of SO2 from areas south of Beijing, with a clear decrease in SO2 concentrations southeast of the 6th to 4th Ring Roads around Beijing and along the 140 km highway from Tianjin to Beijing. The influx of SO2 through the 4th to 6th Ring Roads ranged from 2.1 to 4.6 kg s-1 on 4 September and 0.2 to 1.6 kg s-1 on 20 August 2008. The differences of influx in days were due to the variations of emission changes, transport directions and dilutions. Locally emitted SO2 from a source located along Jingshi Highway outside the southwest section of the 5th Ring Road of Beijing was identified using wind field data generated by the Weather Research and Forecasting model and the measured particle size distribution, with an estimated flux of 0.1 kg s-1 to Beijing. Estimated uncertainties for SO2 influx were approximately 31%. [ABSTRACT FROM AUTHOR]