• Energy Research
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Abstract A great deal of heat is wasted in intensive public shower facilities, such as those in schools, barracks and natatoriums, which open up at specified time. It will contribute a lot to energy saving and environmental protection with significant economic benefits to recycle the exhaust heat. In this paper, we propose two different kinds of heat pumps (an electric heat pump and an absorption heat pump) in the heat recovery systems. In both system, the used shower water is drained through a pipe and collected in a gray water pool. When the wastewater reaches certain volume, the heat pump system will begin working and recycling heat. The wastewater is filtered and piped to the heat exchanger to exchange heat with the tap water whose temperature will increase from 12 °C to 25 °C with the wastewater temperature dropping from 30 °C to 17 °C. Then the wastewater is piped to the heat pump evaporator and the tap water is piped to the condenser for farther heating. According to the different characteristics of the electric heat pump and absorption heat pump, we also introduce the processes and control methods of different heat recovery systems in details in this paper. Based on a practical example, this paper analyzes and compares the economic and environmental benefits of three retrofitting schemes, including “exhaust heat recovery using electric heat pump”, “exhaust heat recovery using electric heat pump + gas boiler” and “exhaust heat recovery using direct-fired heat pump”. Then we find out that the heat recovery system using direct-fired absorption heat pump has lower energy consumption, less pollution, lower operating cost, and shorter payback period. And it has a promising practical application.

In order to enhance the efficiency and benefits of the sludge anaerobic digestion process, K2FeO4 was added to a sludge anaerobic digestion system, and its effects on the system were comprehensively investigated. Results showed that sludge anaerobic digestion was greatly improved by adding 500 mg/L K2FeO4. Biogas and methane productions were increased by 26.6 and 28.4%, respectively. Sludge reduction, protein removal, and the conversion efficiency of dissolved organics were all improved. The mechanism revealed that the disintegration of sludge flocs, enhancement of protease activity, and decrease of soluble sulfide toxicity on microorganisms contributed to biogas production and sludge reduction. Biogas quality was improved, benefitting from the decreasing H2S content in biogas; as additionally, the cost of biogas desulfuration was reduced. In the biogas slurry treatment, the PO43--P concentrations were decreased by 39%, which also reduced the cost of the dephosphorization processes at certain extent.

Abstract Natural gas vehicles offer the benefits of reducing oil use, CO2 emissions and air pollutants. Promoting the use of natural gas vehicles is considered as one of the most important strategies towards sustainable transportation. China made remarkable progress in promoting natural gas vehicles over recent years, and its 4.6 million natural gas vehicles in 2014 represented the world׳s largest natural gas vehicle fleet. In this paper, the development of natural gas vehicles in China is reviewed based on a triple-perspective (Fuel-Vehicle-Infrastructure) technical–economical framework. The review indicates that (a) pricing of vehicle-use Compressed Natural Gas (CNG) and Liquefied Natural Gas (LNG) is essential in determining natural gas vehicle development. A pricing principle similar to the fixed CNG/gasoline price ratio (0.75:1) should be applied to LNG/diesel price ratio; (b) for CNG passenger vehicles, the modified CNG vehicles, with ¥3000–5000 additional cost, is more attractive to consumers than originally manufactured CNG vehicles, with about ¥10,000 additional cost. Vehicle retrofit should be permitted by the government with the precondition that retrofit standards are strictly enforced; (c) for CNG/LNG transit buses, the deployment is strongly affected by local government׳s preference. In regions with sufficient natural gas supply, the government should prioritize the deployment of CNG/LNG transit buses rather than other technologies; (d) for LNG commercial vehicles, with ¥60,000–80,000 higher cost than their counterpart diesel vehicles, financial incentive is critical for their development. China׳s current vehicle subsidy scheme should be extended to cover LNG commercial vehicles; (e) regarding refueling infrastructures, interference with urban land-use planning and long-time administrative approval are the major barriers. Local governments should launch dedicated plans and strategies to support the further deployment of CNG/LNG refueling infrastructures.

A precise energy conservation and emission reduction (ECER) path in industrial sector contains two aspects: applying effective ECER measures and focusing on processes with significant ECER potential. However, most studies have investigated the ECER effects of an individual measure or only evaluated industrial-level ECER potential. Therefore, the objective of this study is to find a precise ECER path in China's iron and steel industry through quantitative analysis methods. First, this article adopts scenario analysis to simulate situations where different ECER measures are adopted and designs calculation methods to quantitatively evaluate the ECER effects in each scenario in 2020 and 2025. Second, through analysis of the application of ECER measures to certain processes, we calculate the ECER potential of different individual processes in the iron and steel industry. In addition, the conservation supply curve method and the quadrant method are used to measure the level of advanced technology application. The results show that: (1) for four types of ECER measures, the limitation of production output measure is most effective, contributing to 6.98% and 12.50% decreases in total industrial energy consumption and pollutant emissions in 2020 and 2025; moreover, the contribution of the adjustment of scale structure measure is comparatively low. (2) The sintering and ironmaking processes have strong ECER potential in 2020, while the steel making process also has high ECER potential in 2025. (3) 21 technologies are divided into 4 quadrants based on energy, popularity, and economic performance. In addition, we provide some suggestions for future ECER policies. In sum, this article provides an in-depth example of determining a precise ECER path in an important industry.

Indoor humidity directly impacts the health of indoor populations. In arid and semi-arid cities, the buildings indoor humidity is typically higher than outdoors, and the presence of water vapor results from water dissipation inside the buildings. Few studies have explored indoor humidity features and vapor distribution or evaluated water dissipation inside buildings. This study examined temperature and relative humidity (RH) changes in typical residential and office buildings. The results indicate a relatively stable temperature with vary range of ±1°C and a fluctuation RH trend which is similarly to that of water use. We proposed the concept of building water dissipation to describe the transformation of liquid water into gaseous water during water consumption and to develop a building water dissipation model that involves two main parameters: indoor population and total floor area. The simulated values were verified by measuring water consumption and water drainage, and the resulting simulation errors were lower for residential than for office buildings. The results indicate that bathroom vapor accounts for 70% of water dissipation in residential buildings. We conclude that indoor humidity was largely a result of water dissipation indoors, and building water dissipation should be considered in urban hydrological cycles.

Net anthropogenic emissions of carbon dioxide (CO2) must approach zero by mid-century (2050) in order to stabilize the global mean temperature at the level targeted by international efforts1-5. Yet continued expansion of fossil-fuel-burning energy infrastructure implies already 'committed' future CO2 emissions6-13. Here we use detailed datasets of existing fossil-fuel energy infrastructure in 2018 to estimate regional and sectoral patterns of committed CO2 emissions, the sensitivity of such emissions to assumed operating lifetimes and schedules, and the economic value of the associated infrastructure. We estimate that, if operated as historically, existing infrastructure will cumulatively emit about 658 gigatonnes of CO2 (with a range of 226 to 1,479 gigatonnes CO2, depending on the lifetimes and utilization rates assumed). More than half of these emissions are predicted to come from the electricity sector; infrastructure in China, the USA and the 28 member states of the European Union represents approximately 41 per cent, 9 per cent and 7 per cent of the total, respectively. If built, proposed power plants (planned, permitted or under construction) would emit roughly an extra 188 (range 37-427) gigatonnes CO2. Committed emissions from existing and proposed energy infrastructure (about 846 gigatonnes CO2) thus represent more than the entire carbon budget that remains if mean warming is to be limited to 1.5 degrees Celsius (°C) with a probability of 66 to 50 per cent (420-580 gigatonnes CO2)5, and perhaps two-thirds of the remaining carbon budget if mean warming is to be limited to less than 2 °C (1,170-1,500 gigatonnes CO2)5. The remaining carbon budget estimates are varied and nuanced14,15, and depend on the climate target and the availability of large-scale negative emissions16. Nevertheless, our estimates suggest that little or no new CO2-emitting infrastructure can be commissioned, and that existing infrastructure may need to be retired early (or be retrofitted with carbon capture and storage technology) in order to meet the Paris Agreement climate goals17. Given the asset value per tonne of committed emissions, we suggest that the most cost-effective premature infrastructure retirements will be in the electricity and industry sectors, if non-emitting alternatives are available and affordable4,18.

This research examines the role of poverty and logistical operations under the circumstance of environmental deterioration with panel data of ASEAN states from 2007 to 2017. The system-generalized method of moments (GMM) was adopted due to the presence of endogeneity. The results indicate that poverty and logistical operations have significant and positive relationship with greater environmental degradation. Because poor people are not skilled, they have to consume natural resources in original and unsustainable way for their survival and profits, which results in greater level of deforestation. On another hand, lacking fuel-efficient/green vehicles and green practices in logistical operations of ASEAN countries, logistics activities mainly depend on fossil fuel consumption, which generates greater carbon emission, methane, and greenhouse emissions that can directly damage the environment and become a primary source of climate change. Therefore, reduction in environmental degradation can be achieved through reduction in poverty and encouraging renewable energy and green practices in logistical operations. In addition, this study also provides detailed policy implications to regulatory bodies and corporate sector in order to improve environmental sustainability through adoption of green practices and reduction in poverty.

Changes in climate patterns not only affect precipitation and precipitation patterns, but also cause the spatiotemporal redistribution of precipitation and runoff, affecting hydrogeneration in turn. Based on the coupling relationship between the Coupled Model Intercomparison Project 5 (CMIP5) climate change model and surface runoff in China, a database of China’s major hydropower stations was constructed in this study and the Water Evaluation and Planning model was applied to analyze the impacts of climate change on hydropower generation in China by region and basin under the Representative Concentration Pathway (RCP)4.5 and RCP8.5 scenarios. During the forecast period, national power generation compared with base year first decreased in the 2030s and then increased in the 2070s, while a risk of excessive hydropower generation was concentrated in the southwestern provinces, Yangtze River Basin, and giant hydropower stations. During the 2030s, hydropower generation may face a risk of electricity generation decrease which will limit its contribution to the Nationally Determined Contribution target.