生活垃圾制备衍生燃料(RDF-5)——以重庆市为例

以重庆市生活垃圾为例,通过分选、破碎和干燥预处理后,得到以塑料、纸类、竹木、织物和厨余为主要成分的制备衍生燃料(RDF-5)的原料,测试了不同含水率和成型压力条件下制得的RDF-5的理化性质.结果表明,原料含水率为8%,成型压力为10 MPa时,RDF-5的延展率和耐性指数良好,便于贮存和运输.燃烧试验表明,RDF-5燃烧后灰渣的热灼减率满足《生活垃圾焚烧污染控制标准》(GB 18485—2014)的要求(5%).另外,根据2006 IPCC国家温室气体名录导则和生命周期评价(LCA),制备RDF-5对温室气体排放贡献为455.92 g·kg-1RDF-5(以CO2当量计).     

我国生活垃圾焚烧发电过程中温室气体排放及影响因素 ——以上海某城市生活垃圾焚烧发电厂为例

以上海某城市生活垃圾焚烧发电厂为例,采用上游-操作-下游(UOD)表格法,分析了生活垃圾焚烧发电过程中不同环节的温室气体排放贡献,及影响其排放的主要因素.结果表明,目前我国生活垃圾焚烧发电过程是温室气体排放源,以吨垃圾净CO2排放量计,达166~212kg.生活垃圾中自含化石碳对温室气体排放的贡献最大,CO2排放量为257kg/t;因焚烧发电上网而获得的净减排量为120kg/t;垃圾收运、辅助物料消耗及焚烧灰渣处理等引起的排放量总计为27~45kg/t.生活垃圾沥出渗滤液后续处理过程的温室气体排放量为7.7kg/t.节省焚烧过程辅助物料使用和改变焚烧灰渣处置方式能够减少温室气体排放量,但是减排效果有限.我国各地区电能基准线排放因子存在差异,对焚烧过程温室气体排放的影响为0~13%.降低生活垃圾含水率、提高垃圾可发电量是我国生活垃圾焚烧发电过程温室气体排放源汇转换的关键途径.     

黄花和脱水污泥厌氧消化的温室气体减排研究

采用联合国政府间气候委员会(IPCC)推荐的方法,对植物加拿大一枝黄花和污泥生物质厌氧消化产沼气的环境和能量影响进行了评估.环境影响评估重点关注温室气体(GHG)减排,将加拿大一枝黄花和脱水污泥的中温小试厌氧消化的甲烷产率数据运用于GHG减排潜质的计算;能量评估包括污泥贮存及传播、消化液的沼气逃逸,及化学肥料和化学药剂的投加几个过程中的直接和间接的能量输入.结果表明,一枝黄花和脱水污泥联合厌氧消化净GHG排放量随着SRT的缩短和黄花添加比例的增加而逐渐下降,在二者以挥发性固体(VS)比例1:1混合,停留时间为20d时的能量效率较高,GHG减排量较大,与基础方案相比,添加黄花可以实现78%的净GHG减排.     

氮肥管理措施对黑土玉米田温室气体排放的影响

采用静态箱-气相色谱法研究了不同氮肥管理措施(农民常规施肥、减氮20%、添加硝化抑制剂、施用控释肥)对黑土玉米田温室气体排放的影响.结果表明:黑土玉米田施肥(基肥和追肥)后1~3d出现N2O排放峰,施肥后16d内N2O排放量占生育期总排放量的28.8%~41.9%.减施氮肥20%显著降低土壤N2O排放,生育期内的N2O累积排放量减少了17.6%~46.1%,综合温室效应降低30.7%~67.8%,温室气体排放强度降低29.1%~67.0%.等氮量投入时,添加吡啶抑制剂土壤N2O排放量、综合温室效应和温室气体排放强度最低.玉米拔节~乳熟期出现了较强的土壤CO2排放,黑土玉米田是大气中CH4的一个较弱的“汇”,施氮和添加硝化抑制剂对黑土玉米田CO2排放和CH4吸收没有显著影响.添加硝化抑制剂和施用控释肥不影响玉米产量.在本试验条件下,减氮20%并添加吡啶抑制剂在保证玉米产量的同时, 减排增收效果优于其他施肥措施,适宜在黑土区玉米种植中推广使用.     

广东电力生产的温室气体排放趋势和演变特征

通过文献调研收集广东电力生产最新的能源消费数据和排放因子,采用“自上而下”方法估算1995—2011年广东电力行业的直接和间接GHG(温室气体)排放量,量化直接排放量的不确定性,绘制GHG排放流向图,并且根据GHG排放特征提出减排建议. 结果表明:①虽然受经济、环境和能源政策的影响,与1995年相比,2011年广东电力生产的GHG总排放量仍增长438%,达3.44×108 t,其中直接排放量达2.78×108 t,不确定性为±11%. ②从发电能源结构角度考虑,燃煤发电是电力生产的最大GHG排放源,2011年其排放量占总排放量的76%;而从用电终端考虑,工业用电是最大的GHG排放源,2011年其排放量占电力生产GHG总排放量的66%. ③1995—2011年,用电终端总体电力GHG排放强度下降了16%,居民用电人均GHG排放量上升了260%,单位综合发电量的GHG排放系数微升了1%. ④发电能源结构和终端产业结构的低碳化以及控制居民用电的GHG排放量等措施可减排2011年广东电力生产GHG总排放量的44%.      

温室气体减排项目评价方法研究

阐述了温室气体减排技术选择的准则与优先领域,以及温室气体减排项目评价应包括的主要内容;对3类主要的温室气体减排项目——节能技术改造项目、新建提高能源转换或利用效率项目及能源替代项目,分别探讨了基准线的确定方法、减排量和增量减排成本的计算方法在这3个项目评价中的难点;介绍了温室气体间接减排项目评价方法;最后以张北风电场二期风电项目为例对全球环境效益进行评价。      

Energy Embodied in Goods in International Trade of China: Calculation and Policy Implications

Abstract

In recent years, China’s energy demand and Greenhouse gas (GHG) emissions have grown very fast, quite an amount of which was exported as energy embodied in goods in international trade rather than consumed domestically. Starting from the concept of embodied energy, based on input-output energy analysis approach, in this paper the energy embodied in goods in international trade of China during the period from 2001 to 2006 is calculated. The results show that although China has become a net importer of petroleum since 1993, China is a net exporter of embodied energy due to international trade in goods. In 2002, the total amount of energy embodied in exported goods was about 410 million tce (ton of coal equivalent, hereinafter referred to as “tce”). Eliminating the amount of energy embodied in imported goods of about 170 million tce, the net export of embodied energy was about 240 million tce, accounting for 16% of the aggregate primary energy consumption of that very year in China, and the net export of embodied emissions was about 150 million tons of carbon. With the rapid growth of China’s international trade, assuming no structural input-output changes of among sectors, in 2006 the net export of embodied energy went up to about 630 million tce, an increase of 162 % over 2002. In addition, this paper also analyzes the possible sources of error in calculation, and also discusses the policy implications according to the result of the calculation.     

Greenhouse gas emissions from landfill leachate treatment plants: A comparison of young and aged landfill

With limited assessment, leachate treatment of a specified landfill is considered to be a significant source of greenhouse gas (GHG) emissions. In our study, the cumulative GHG emitted from the storage ponds and process configurations that manage fresh or aged landfill leachate were investigated. Our results showed that strong CH₄ emissions were observed from the fresh leachate storage pond, with the fluxes values (2219–26,489 mg C m^?2 h^?1) extremely higher than those of N₂O (0.028–0.41 mg N m^?2 h^?1). In contrast, the emission values for both CH₄ and N₂O were low for the aged leachate tank. N₂O emissions became dominant once the leachate entered the treatment plants of both systems, accounting for 8–12% of the removal of N-species gases. Per capita, the N₂O emission based on both leachate treatment systems was estimated to be 7.99 g N₂O–N capita^?1 yr^?1. An increase of 80% in N₂O emissions was observed when the bioreactor pH decreased by approximately 1 pH unit. The vast majority of carbon was removed in the form of CO₂, with a small portion as CH₄ (<0.3%) during both treatment processes. The cumulative GHG emissions for fresh leachate storage ponds, fresh leachate treatment system and aged leachate treatment system were 19.10, 10.62 and 3.63 Gg CO₂ eq yr^?1, respectively, for a total that could be transformed to 9.09 kg CO₂ eq capita^?1 yr^?1.     

Achieving the Kyoto Protocol in the U.S.: How Great are the Needed Changes?

The Kyoto Protocol requires the U.S.to reduce the rate of emissions of six greenhousegases (GHG) to 93% of their 1990 rate and to achievethis target by the 2008 to 2012 commitment period. This study assesses the magnitude of change needed inthe U.S. economy and, specifically, in the U.S. energysector, to achieve and maintain the target establishedby the Kyoto Protocol. A simple carbon (C)emissions-energy model is explained in this analysisusing four key variables. Current and future trendsin C emissions are explained by: the carbon/energy(C/E) ratio, Gross Domestic Product growth, energyprices and an energy trend variable. Potential GHGmitigation policy actions affect C emissionsindirectly by affecting at least one of these keyvariables. The analysis concludes that reducingfossil energy use in the U.S. to meet the Kyoto GHGemissions reduction target would be very costly. Technological progress that reduces C emissions wouldnot be fully sufficient without prematurely abandoningproductive capital equipment. Energy price increasesof about 14% per year, or declines in economic growthof almost 5% per year, could reduce energy demand andassociated C emissions enough to achieve the terms ofthe Kyoto Protocol.     

No-policy greenhouse gas emission scenarios: revisiting IPCC 1992

A new set of no-policy global greenhouse gas (GHG) emission scenarios was developed using the atmospheric stabilization framework, the same modeling tool that was used to generate the IS92 emission scenarios for the Intergovernmental Panel on Climate Change. Revised assumptions about population and economic growth, combined with updated information on changes in renewable energy supply, the efficiency of energy generation and other factors resulted in changes in GHG emission profiles over the next century, which led to an increase in the estimated global average temperature change as compared to the IS92 scenarios. Model results indicate that the largest increase in emissions, which led to a temperature increase of about 3.4°C by 2100 (relative to 1990), can be expected when a rapid increase in the GNP per capita levels of the non-OECD countries is combined with a low availability of solar/wind and biomass energy resources and slow energy efficiency improvements. The smallest increase in emissions and temperature by 2100 (about 2.5°C) occurred when a relatively slow increase in the GNP per capita in the non-OECD countries was combined with a high availability of renewable energy resources and rapid energy efficiency improvements.