中国的能源发展与应对气候变化

我国当前经济社会发展既受到资源环境的瓶颈性制约,也受到全球应对气候变化、减缓碳排放的严峻挑战.我国大力推进节能和减缓CO2排放,GDP的CO2强度下降速度为世界瞩目,但由于工业化阶段GDP快速增长,CO2排放仍呈增长快、总量大的趋势.我国把国内可持续发展与全球应对气候变化相协调,实现绿色、低碳发展.加强产业结构的战略性调整,进行产业升级,促进结构节能;大力推广节能技术,淘汰落后产能,提高能源效率;积极发展新能源和可再生能源,优化能源结构,降低能源结构的含碳率,中近期以大幅度降低GDP的能源强度和CO2强度为主要目标,到2030年前后要努力使CO2排放达到峰值,到2050年再有较大幅度的下降,以适应全球控制温升不超过2℃长期减排目标下国际合作应对气候变化的进程和形势.“十二五”期间将进一步强化措施,进行能源消费总量控制,建立CO2排放统计、核算和考核体系,积极推进碳交易市场机制,这也将成为加快转变经济发展方式的重要着力点.     

城镇化过程中的碳排放来源

改革开放以来,我国城镇化呈现快速发展趋势。2013年城镇化率达到53.7%,年均增长3.10%,是建国至改革开放之前城镇化年均增长率(1.75%)的近2倍。与此同时,碳排放总量增长至35年前的6.2倍,人均碳排放增长至35年前的4.4倍。城镇化过程伴随着高碳排放,增长速率高于城镇化发展速度。这预示着我国未来城镇化发展将面临巨大的高碳排放压力。如何降低城镇化过程中的碳排放成为亟待解决的问题。本文将城镇化过程中导致高碳排放的各因素归纳为经济、政治两项因素,对我国城镇化过程中工业、建筑、交通、地方政府等导致高碳排放结果的行为加以区分。研究发现,城镇化过程中的工业高碳排放、建筑面积扩张与其使用效率的背离、交通出行需求量的持续上升、居民生活水平提高带来的消费力增加,城市低密度扩张以及其背后地方政府官员考核机制与地方财税制度的弊端,是我国目前城镇化呈现高碳发展状态的主要原因。由此可见,过去的城镇化发展模式非低碳、非持续是有其深刻的经济与政治原因的。中长期的低碳转型只有把经济手段和制度调整结合,低碳发展理念才有可能实现。     

中国资源型城市CO_2排放比较研究

城市,特别是资源型城市,作为践行国家应对气候变化战略行动的重要主体,在绿色发展转型以及生态文明建设进程中正面临诸多现实挑战。资源型城市能否实现低碳发展转型,关乎我国在国际社会上承诺的中长期碳减排目标能否最终实现。为此,本研究基于中国高空间分辨率网格数据(CHRED),综合运用DPSIR(驱动力-压力-状态-影响-响应)、分类比较研究和情景分析等方法,对我国126个资源型城市的CO_2排放特征进行了系统分析,揭示了这些城市在能源结构和产业结构方面面临的诸多挑战,分析了这些城市未来碳排放趋势和碳减排潜力。研究结果显示:在正常达峰情景下,2030年126个资源型城市将以72.65亿t的CO_2排放量达峰,约占当年全国CO_2排放总量的60%;在提前达峰情景下,资源型城市将在2025年以53.78亿t的CO_2排放量达峰,约占当年全国CO_2排放总量的45%左右。最后,针对我国资源型城市的绿色低碳发展转型以及碳排放达峰管理提出几点建议:一是加强能源统计工作,促进资源型城市碳排放信息化管理平台建设;二是加强体制机制建设,健全资源型城市绿色低碳转型制度体系;三是改善以煤炭等化石燃料为主导的能源消费结构,提高清洁燃料利用的比重;四是加快绿色低碳技术发展,推动产业优化升级和碳排放强度明显下降。     

Is pork trade good for China's greenhouse gas emissions?

China produces the largest amount of pork in the world, which emits the largest amount of greenhouse gases (GHGs). This paper calculates GHG emissions from China’s hog production at the provincial level using newly published emission factors. Empirical results show that GHG emissions from China’s hog production mainly respond to the scale intensity. Capital abundance and income contribute positively to GHG emissions from hog production. Pork trade increases GHG emissions from China’s hog production with a significantly direct effect, reduces GHG emissions through indirect technique effects.     

Responses of CH(4), CO(2) and N(2)O fluxes to increasing nitrogen deposition in alpine grassland of the Tianshan Mountains

To assess the effects of nitrogen (N) deposition on greenhouse gas (GHG) fluxes in alpine grassland of the Tianshan Mountains in central Asia, CH₄, CO₂ and N₂O fluxes were measured from June 2010 to May 2011. Nitrogen deposition tended to significantly increase CH₄ uptake, CO₂ and N₂O emissions at sites receiving N addition compared with those at site without N addition during the growing season, but no significant differences were found for all sites outside the growing season. Air temperature, soil temperature and water content were the important factors that influence CO₂ and N₂O emissions at year-round scale, indicating that increased temperature and precipitation in the future will exert greater impacts on CO₂ and N₂O emissions in the alpine grassland. In addition, plant coverage in July was also positively correlated with CO₂ and N₂O emissions under elevated N deposition rates. The present study will deepen our understanding of N deposition impacts on GHG balance in the alpine grassland ecosystem, and help us assess the global N effects, parameterize Earth System models and inform decision makers.     

内地与香港燃煤电厂大气污染物排放控制政策与标准比较

香港特区与广东省政府联合成立粤港持续发展与环保合作小组,并发表《改善珠江三角洲空气质量的联合声明》（简称＂减排联合声明＂）,同意制定合理的减排方案,共同执行管理计划。总结分析了粤、港地区在治理燃煤电厂大气污染物方面的控制政策,并对大陆与香港特区燃煤电厂大气污染物的排放标准进行比较。     

Evaluation of methods for the physical characterization of the fine particle emissions from two residential wood combustion appliances

The fine particle emissions from a U. S. certified non-catalytic wood stove and a zero-clearance fireplace burning Quercus rubra L. (northern red oak) and Pseudotsuga menziesii (Douglas fir) cordwood each at two different moisture levels were determined. Emission testing was performed using both time-integrated and continuous instrumentation for total particle mass, particle number, particle size distribution, and fixed combustion gases using an atmospheric wind tunnel, full-flow laboratory dilution tunnel, and dilution stack sampler with a comparison made between the three dilution systems and two sampling filter types. The total mass emission factors (EFs) for all dilution systems and filter media are extremely variable ranging from <1 to 55 g kg⁻¹ of dry wood depending on the combination of appliance type, wood species and moisture content, filter medium, and dilution system. For Teflon filter sampling of stove emissions in the wind tunnel, the total mass EFs varied from 2 to 8 g kg⁻¹ of dry fuel depending on wood type whereas the equivalent fireplace emissions burning wet oak averaged 11 g kg⁻¹. A substantial number of ultrafine particles in the accumulation size range were also observed during all tests as determined by an Electrical Low Pressure Impactor (ELPI) and Scanning Mobility Particle Sizer. The PM-2.5 (particles ≤2.5 μm in aerodynamic diameter) fractions determined from the ELPI electrometer data ranged from 93 to 98% (mass) depending on appliance type as reported previously by Hays et al. (Aerosol Science, 34, 1061, 2003).     

Environmental evaluation of transfer and treatment of excess pig slurry by life cycle assessment

Slurry management is a central topic in the agronomic and environmental analysis of intensive livestock production systems. The objective of this study is to compare the environmental performance of two scenarios of collective slurry management for the disposal of excess nitrogen from animal manure. The scenarios are the transfer of slurry and its injection to crop land, and the treatment of slurry in a collective biological treatment station. The study is based on a real case in the West of France, where a group of farmers is developing a collective plan for the disposal of almost 7000 m(3) of excess pig slurry. The evaluation is carried out by Life Cycle Assessment, where emissions and resource consumption are quantified and aggregated into four environmental impact categories: eutrophication, acidification, climate change, and non-renewable energy use. Ammonia emitted is the most important contributor to acidification and eutrophication, while methane contributes most to climate change. Both ammonia and methane are mostly emitted during the storage of slurry and, in the case of the treatment scenario, also during composting the solid fraction of the slurry. The two management strategies are similar with respect to climate change, whereas eutrophication and acidification are twice as large for treatment relative to transfer. Electricity needed for the treatment process is the main contributor to non-renewable energy use for the treatment scenario, while the transfer scenario represents a net energy saving, as energy saved by the reduction of mineral fertiliser use more than compensates for the energy needed for transport and injection of slurry. The overall environmental performance of transfer is better than that of treatment, as it involves less acidification, eutrophication and non-renewable energy use. The method employed and the results obtained in this study can provide elements for a transparent discussion of the advantages and disadvantages of contrasting excess slurry management scenarios as well as the identification of the main aspects determining their environmental performance.     

Responses of herbaceous plants to urban air pollution: Effects on growth, phenology and leaf surface characteristics

Vehicle exhaust emissions are a dominant feature of urban environments and are widely believed to have detrimental effects on plants. The effects of diesel exhaust emissions on 12 herbaceous species were studied with respect to growth, flower development, leaf senescence and leaf surface wax characteristics. A diesel generator was used to produce concentrations of nitrogen oxides (NO_x) representative of urban conditions, in solardome chambers. Annual mean NO_x concentrations ranged from 77 nl l^−l to 98 nl l⁻¹, with NO:NO₂ ratios of 1.4-2.2, providing a good experimental simulation of polluted roadside environments. Pollutant exposure resulted in species-specific changes in growth and phenology, with a consistent trend for accelerated senescence and delayed flowering. Leaf surface characteristics were also affected; contact angle measurements indicated changes in surface wax structure following pollutant exposure. The study demonstrated clearly the potential for realistic levels of vehicle exhaust pollution to have direct adverse effects on urban vegetation.     

Determination of urine-derived odorous compounds in a source separation sanitation system

Source separation sanitation systems have attracted more and more attention recently.However, separate urine collection and treatment could induce odor issues, especially in large scale application. In order to avoid such issues, it is necessary to monitor the odor related compounds that might be generated during urine storage. This study investigated the odorous compounds that emitted from source-separated human urine under different hydrolysis conditions. Batch experiments were conducted to investigate the effect of temperature, stale/fresh urine ratio and urine dilution on odor emissions. It was found that ammonia, dimethyl disulfide, allyl methyl sulfide and 4-heptanone were the main odorous compounds generated from human urine, with headspace concentrations hundreds of times higher than their respective odor thresholds. Furthermore, the high temperature accelerated urine hydrolysis and liquid–gas mass transfer, resulting a remarkable increase of odor emissions from the urine solution. The addition of stale urine enhanced urine hydrolysis and expedited odor emissions. On the contrary, diluted urine emitted less odorous compounds ascribed to reduced concentrations of odorant precursors. In addition,this study quantified the odor emissions and revealed the constraints of urine source separation in real-world applications. To address the odor issue, several control strategies are recommended for odor mitigation or elimination from an engineering perspective.