Greenhouse gas balances of molasses based ethanol in Nepal

This paper evaluates life cycle greenhouse gas (GHG) balances in production and use of molasses-based ethanol (EtOH) in Nepal. The total life cycle emissions of EtOH is estimated at 432.5 kgCO_2eq m⁻³ ethanol (i.e. 20.4 gCO_2eq MJ⁻¹). Avoided emissions are 76.6% when conventional gasoline is replaced by molasses derived ethanol. A sensitivity analysis was performed to verify the impact of variations in material and energy flows, and allocation ratios in the GHG balances. Market prices of sugar and molasses, amount of nitrogen-fertilizers used in sugarcane production, and sugarcane yield per hectare turn out to be important parameters for the GHG balances estimation. Sales of the surplus electricity derived from bagasse could reduce emissions by replacing electricity produced in diesel power plants. Scenario analysis on two wastewater processes for treatment of effluents obtained from ethanol conversion has also been carried out. If wastewater generated from ethanol conversion unit is treated in pond stabilization (PS) treatment process, GHG emissions alarmingly increase to a level of 4032 kgCO_2eq m⁻³ ethanol. Results also show that the anaerobic digestion process (ADP) and biogas recovery without leakages can significantly avoid GHG emissions, and improve the overall emissions balance of EtOH in Nepal. At a 10% biogas leakage, life cycle emissions is 1038 kgCO_2eq m⁻³ ethanol which corresponds to 44% avoided emissions compared to gasoline. On the other hand, total emissions surpass the level of its counterpart (i.e. gasoline) when the leakage of biogas exceeds 23.4%.     

Modern Biomass Conversion Technologies

This article gives an overview of the state-of-the-art of key biomass conversion technologies currently deployed and technologies that may play a key role in the future, including possible linkage to CO₂ capture and sequestration technology (CCS). In doing so, special attention is paid to production of biofuels for the transport sector, because this is likely to become the key emerging market for large-scale sustainable biomass use. Although the actual role of bio-energy will depend on its competitiveness with fossil fuels and on agricultural policies worldwide, it seems realistic to expect that the current contribution of bio-energy of 40–55 EJ per year will increase considerably. A range from 200 to 300 EJ may be observed looking well into this century, making biomass a more important energy supply option than mineral oil today. A key issue for bio-energy is that its use should be modernized to fit into a sustainable development path. Especially promising are the production of electricity via advanced conversion concepts (i.e. gasification and state-of-the-art combustion and co-firing) and modern biomass derived fuels like methanol, hydrogen and ethanol from ligno-cellulosic biomass, which can reach competitive cost levels within 1–2 decades (partly depending on price developments with petroleum). Sugar cane based ethanol production already provides a competitive biofuel production system in tropical regions and further improvements are possible. Flexible energy systems, in which biomass and fossil fuels can be used in combination, could be the backbone for a low risk, low cost and low carbon emission energy supply system for large scale supply of fuels and power and providing a framework for the evolution of large scale biomass raw material supply systems. The gasification route offers special possibilities to combine this with low cost CO₂ capture (and storage), resulting in concepts that are both flexible with respect to primary fuel input as well as product mix and with the possibility of achieving zero or even negative carbon emissions. Prolonged RD&D efforts and biomass market development, consistent policy support and international collaboration are essential to achieve this.     

Mass-cultivation of carbohydrate rich macroalgae, a possible solution for sustainable biofuel production

Global demand for bio-fuels continues unabated. Rising concerns over environmental pollution and global warming have encouraged the movement to alternate fuels, the world ethanol market is projected to reach 86 billion litres this year. Bioethanol is currently produced from land-based crops such as corn and sugar cane. A continued use of these crops drives the food versus fuel debate. An alternate feed-stock which is abundant and carbohydrate-rich is necessary. The production of such a crop should be sustainable, and, reduce competition with production of food, feed, and industrial crops, and not be dependent on agricultural inputs (pesticides, fertilizer, farmable land, water). Marine biomass could meet these challenges, being an abundant and carbon neutral renewable resource with potential to reduce green house gas (GHG) emissions and the man-made impact on climate change. Here we examine the current cultivation technologies for marine biomass and the environmental and economic aspects of using brown seaweeds for bio-ethanol production.     

Life cycle assessment of electricity generation from bagasse in Mauritius

This paper presents the findings of a life cycle assessment (LCA) of electricity generated from the combustion of sugar cane bagasse in Mauritian sugar mills. The study arose from the identification of the need for to provide data for the development of an LCA profile for the electricity mix in Mauritius. The system is limited geographically to the island of Mauritius and is intended to be the representative of current agricultural techniques practiced and current manufacturing processes used by Mauritian sugar mills. The unit operations that make up the system are the growing and harvesting of sugar cane, the transport of the harvested cane to sugar mills, the production of bagasse as a by-product from the sugar milling process, and the combustion of bagasse to generate heat and electricity. The functional unit of the study is the generation of 1 GWh of electricity exported to the national electricity grid. The characterised data for 1 GWh of bagasse-derived electricity were compared with data for 1 GWh of coal-derived electricity, using the same set of characterisation factors. The results of this comparison indicate that bagasse-derived electricity performs well in the areas of greenhouse gas emissions, acidification, and non-renewable energy inputs, but performs poorly in relation to water consumption and eutrophication.     

Life cycle assessment as a decision support tool for landfill gas-to energy projects

The greenhouse gas (GHG) emissions from MSW landfill, and control methods to eliminate or minimize these impacts including energy recovery from landfill gas (LFG) of MSW landfill in Thailand have been evaluated. Life Cycle Assessment (LCA) is used as the analytical tool to evaluate the environmental consequences of landfilling holistically. The economic implications of the control methods are also briefly assessed. The results show that in terms of GHG emissions as well as in terms of economics, it is more advantageous to have a large centralized landfill and produce electricity from the LFG rather than having several small, localized landfills despite significantly lower transportation requirement for the latter case. Sensitivity analysis revealed that the global warming potential was sensitive to gas collection efficiency as well as methane oxidation rate in the landfill. This study shows the utility of a life cycle approach for evaluating LFG-to-energy (LFGTE) projects.     

Environmental impacts of distributed energy systems—The case of micro cogeneration

Distributed generation in micro cogeneration systems, e.g. reciprocating or Stirling engines and fuel cells, is of increasing interest in the energy market. This paper investigates environmental impacts of micro cogeneration by carrying out a detailed life cycle assessment and an analysis of local air quality impacts of micro cogeneration systems.Most micro cogeneration systems are superior, as far as the reduction of GHG emissions is concerned, not only to average electricity and heat supply, but also to state-of-the art separate production of electricity in gas power plants and heat in condensing boilers. The GHG advantages of micro cogeneration plants are comparable to district heating with CHP. Under the assumption that gas condensing boilers are the competing heat-supply technology, all technologies are within a very narrow range. Looking at the GHG reduction potential on the level of a supply object (e.g. a single-family house) by modeling the operation with a CHP optimization tool, the achievable mitigation potential is somewhat lower, because the micro cogeneration systems do not supply the whole energy demand. Here, fuel cells offer the advantage of a higher power-to-heat ratio.Environmental impacts other than those related to climate and resource protection relate more specifically to technology. In addition to investigating the emissions side, analysis of the air quality situation of a residential area supplied by reciprocating engines was carried out. The analysis shows that for the selected conditions, the additional emission of NO_x due to the engines do not create severe additional environmental impacts.     

Integration of Solid Oxide Fuel Cell in a sugar-ethanol factory: analysis of the efficiency and the environmental profile of the products

The effect of the integration of Solid Oxide Fuel Cell (SOFC) technology in a sugar-ethanol factory on the environmental profile/footprint of the products (sugar, ethanol, electricity) is evaluated. The sugarcane is the primary feedstock and sugar, ethanol and electricity are the main products of the system, where the functional unit is defined as 9.86 ton/h of sugar, 2.195 ton/h of hydrated ethanol (96% w/w) and 847 kWh of electricity. A detailed set of material and energy inputs and outputs was obtained from a local factory and was completed using simulation data by Aspen Plus^®.The environmental impacts (greenhouse gases and air pollution), exergy efficiency and a renewability parameter have been considered as indicators for the comparative assessment with conventional sugar, ethanol and electricity production technologies. The results show that the use of a SOFC technology involves a reduction of greenhouse gas emissions (52-55%) and non-renewable resources (60-64%) when compared with the conventional integrated sugar and ethanol plant. The higher renewability index (0.93) and exergy efficiency (38%) are noticed for the Solid Oxide Fuel Cell technology integrated in the sugar-ethanol factory than conventional sugar-ethanol plant.     

Greenhouse gas mitigation with scarce land: The potential contribution of increased nitrogen input

Agricultural lands have been identified to mitigate greenhouse gas (GHG) emissions primarily by production of energy crops and substituting fossil energy resources and through carbon sequestration in soils. Increased fertilizer input resulting in increased yields may reduce the area needed for crop production. The surplus area could be used for energy production without affecting the land use necessary for food and feed production. We built a model to investigate the effect of changing nitrogen (N) fertilizer rates on cropping area required for a given amount of crops. We found that an increase in nitrogen fertilizer supply is only justified if GHG mitigation with additional land is higher than 9–15 t carbon dioxide equivalents per hectare (CO₂-eq._./ha). The mitigation potential of bioenergy production from energy crops is most often not in this range. Hence, from a GHG abatement point of view land should rather be used to produce crops at moderate fertilizer rate than to produce energy crops. This may change if farmers are forced to reduce their N input due to taxes or governmental regulations as it is the case in Denmark. However, with a fertilizer rate 10 % below the economical optimum a reduction of N input is still more effective than the production of bioenergy unless mitigation effect of the bioenergy production exceeds 7 t carbon dioxide (CO₂)-eq._./ha. An intensification of land use in terms of N supply to provide more land for bioenergy production can only in exceptional cases be justified to mitigate GHG emissions with bioenergy under current frame conditions in Germany and Denmark.     

城市废弃物处理温室气体排放研究:以厦门市为例

城市废弃物处理是城市人为活动产生温室气体的来源之一.参考IPCC国家温室气体清单指南2006推荐的方法建立了厦门市废弃物处理的温室气体排放计算模型,对厦门市2005～2010年废弃物处理的温室气体排放情况进行了估算,包括固体废弃物填埋、焚烧以及污水处理等过程.结果表明,2005年温室气体总排放量折合二氧化碳当量(CO2e)为406.3 kt,2010年温室气体总排放量(以CO2e计)达到704.6 kt,随着废水处理工艺的提高和城市生活垃圾量的迅速增长,主要排放源由废水处理转变为固体废弃物填埋.2005年填埋产生的温室气体排放占固体废弃物处理排放量的90%左右,2010年所占比例下降到75%.厦门市废水处理温室气体排放量2007年最高,以CO2e计达到325.5 kt,化学原料及化学品制造业从2005～2010年一直是厦门市CH4排放量最高的产业,占工业废水处理CH4排放总量的55%以上.     

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%.      

Greenhouse gas emissions,life-cycle inventory and cost-efficiency of using laminated wood instead of steel construction.: Case: beams at Gardermoen airport

This article compares the use of glulam beams at the new airport outside Oslo with an alternative solution in steel in order to (1) make an inventory of greenhouse gas (GHG) emissions and energy use over the life cycle of glulam and of steel, (2) calculate the avoided GHG emissions and the cost of the substitution, and (3) analyse which factors have the strongest influence on the results. Compared to previous analyses of substitution between steel and glulam related to greenhouse gas emissions, this article brings in three new methodological elements: combining traditional life-cycle analysis with economic costs, considering explicitly the emissions’ points in time, and using discounted global warming potential (DGWP).The total energy consumption in manufacturing of steel beams is two to three times higher and the use of fossil fuel 6–12 times higher than in the manufacturing of glulam beams. Manufacturing of steel in the most likely scenario gives five times higher GHG emissions compared to manufacturing of glulam beams. Waste handling of glulam can either be very favourable or unfavourable compared to steel depending on the glulam being landfilled or used for energy production. Other assumptions that substantially affect the results over the life cycle are carbon fixation on the forest land that is regenerated after harvesting, whether the steel production is scrap-based or ore-based, and which energy sources are used for producing the electricity used by the steel industry. The uncertainty in the inventory data for glulam do not influence the results much compared to changes in these main assumptions. The glulam construction cannot be more than 1–6% more expensive than steel before the price per ton avoided greenhouse gas emissions becomes high compared to the present Norwegian CO₂-tax on gasoline. In the most likely scenario, and not including carbon fixation on forest land, 0.24–0.31 tons of CO₂-equivalents per cubic metre input of sawn wood in glulam production is avoided by using glulam instead of steel, whereas this figure increases to 0.40–0.97 t/m³ if carbon fixation on forest land is included. Using DGWP does not influence the results of the analysis significantly.     

Greenhouse gas emissions from production and use of used cooking oil methyl ester as transport fuel in Thailand

Biodiesel, produced from various vegetable and/or animal oils, is one of the most promising alternative fuels for transportation in Thailand. Currently, the waste oils after use in cooking are not disposed adequately. Such oils could serve as a feedstock for biodiesel which would also address the waste disposal issue. This study compares the life cycle greenhouse gas (GHG) emissions from used cooking oil methyl ester (UCOME) and conventional diesel used in transport. The functional unit (FU) is 100 km transportation by light duty diesel vehicle (LDDV) under identical driving conditions. Life cycle GHG emissions from conventional diesel are about 32.57 kg CO₂-eq/FU whereas those from UCOME are 2.35 kg CO₂-eq/FU. The GHG emissions from the life cycle of UCOME are 93% less than those of conventional diesel production and use. Hence, a fuel switch from conventional diesel to UCOME will contribute greatly to a reduction in global warming potential. This will also support the Thai Government's policy to promote the use of indigenous and renewable sources for transportation fuels.     

Comparative Life Cycle Assessment of four alternatives for using by-products of cane sugar production

Cane sugar production by-products can be considered either as waste, affecting the environment, or as a resource when an appropriate valorization technology is implemented.This study is made with the objective of identifying and quantifying the aspects which have the largest environmental impact of four alternatives for using by-products and wastes from the cane sugar process and suggest improvements in the systems.For this analysis a cane sugar mill was chosen in Cuba and four alternatives were designed for the by-product valorization. The first alternative represents the conventional sugar production; its main characteristics are the use of synthetic fertilizers, pesticides, the bagasse combustion and the usage of molasses and agricultural wastes as animal food. Other wastes constitute emissions to the environment. Alternatives II, III and IV incorporate more use of by-products and wastes. Alternative II considers the use of wastewater, filter cake and ashes for the substitution of synthetic fertilizers. In Alternative III, the filter cake and wastewater are used for biogas production and Alternative IV integrates alcohol and biogas production into the sugar production process.The assessment is done by means of Life Cycle Assessment, according to the ISO 14040 series by using the SimaPro 6.0 LCA software, Ecoinvent database and the Eco-indicator 99 methodology. As a functional unit the daily sugar production of the mill was defined (216 t/d). The sugar was selected as main product and all the by-products were assumed to substitute other products on the market, avoided products.For the four alternatives, the agricultural stage shows the greatest impact due to land use, fuel and agrochemicals consumption. In the industrial stage, the electricity cogeneration with bagasse has the highest impact as to respiratory effects due to the emission of tiny particle material into the atmosphere. The major difference between the alternatives is found in the resource impact category. The advantage of producing alcohol, biogas, animal food and fertilizers from the by-products is made obvious through the comparative study for resource savings.     

Quantifying and managing regional greenhouse gas emissions：Waste sector of Daejeon, Korea

A credible accounting of national and regional inventories for the greenhouse gas （GHG） reduction has emerged as one of the most significant current discussions. This article assessed the regional GHG emissions by three categories of the waste sector in Daejeon Metropolitan City （DMC）, Korea, examined the potential for DMC to reduce GHG emission, and discussed the methodology modified from Intergovernmental Panel on Climate Change and Korea national guidelines. During the last five years, DMC＇s overall GHG emissions were 239 thousand tons C02 eq./year from eleven public environmental infrastructure facilities, with a population of 1.52 million. Of the three categories, solid waste treatment/disposal contributes 68%, whilst wastewater treatment and others contribute 22% and 10% respectively. Among GHG unit emissions per ton of waste treatment, the biggest contributor was waste incineration of 694 kg CO2 eq./ton, followed by waste disposal of 483 kg CO2 eq./ton, biological treatment of solid waste of 209 kg CO2 eq./ton, wastewater treatment of 0.241 kg CO2 eq./m3, and public water supplies of 0.067 kg CO2 eq./m3. Furthermore, it is suggested that the potential in reducing GHG emissions from landfill process can be as high as 47.5% by increasing landfill gas recovery up to 50%. Therefore, it is apparent that reduction strategies for the main contributors of GHG emissions should take precedence over minor contributors and lead to the best practice for managing GHGs abatement.     

Bioenergy and the forest industry in Finland after the adoption of the Kyoto protocol

In Finland the percentage of biomass fuels of total primary energy supply is relatively high, close to 17%. The share of biomass in the total electricity generation is as much as 10%. This high share in Finland is mainly due to the cogeneration of electricity and heat within forest industry using biomass-based by-products and wastes as fuels. Forest industry is also a large user of fossil-based energy. About 28% of total primary energy consumption in Finland takes place in forest industry, causing about 16% of the total fossil carbon dioxide emissions.The Kyoto protocol limits the fossil CO₂ and other greenhouse gas emissions and provides some incentives to the Finnish forest sector. There are trade-offs among the raw-material, energy and carbon sink uses of the forests. Fossil emissions can be reduced e.g. by using more wood and producing chemical pulp instead of mechanical one. According to the calculation rules of the Kyoto protocol Finnish forests in 2008–2012 are estimated to form a carbon source of 0.36 Tg C a⁻¹ due to land use changes. Factually the forest biomass will still be a net carbon sink between 3.5 and 8.8 Tg C a⁻¹. Because the carbon sinks of existing forests are not counted in the protocol, there is an incentive to increase wood use in those and to decrease the real net carbon sink. Also the criteria for sustainable forestry could still simultaneously be met.     

Utilization of Bagasse Energy in Thailand

Bagasse, a biomass fuel, is the waste generated by the sugar-making process from sugar cane. Sugar making is one of the most important agricultural-produce processing industries for developing countries in Southeast Asia, Latin America and Africa. As sugar producing plants need electric power and process steam, co-generation using bagasse as an alternate fuel for petroleum has been in use for some time. Thailand recently became one of the largest sugar exporters by enlarging plant capacities and improving equipment, thus reducing its production cost. In addition, the Thai government promotes power generation using bagasse as a means to combat global warming by raising the purchase price of the surplus power. The industry is in the process of further raising the plant capacity, and improving the power-generating efficiency. This will enable a plant to generate more electric power than its in-plant need so that the surplus power can be sold to the commercial grid. It also plans to become a local power supplier during off-season of sugar making by adding a condensing turbine generator. A typical Thai sugar plant of the latest design generates steam of 4Mpa at the bagasse boiler outlet with the temperature of 400°C at 84% boiler efficiency. With the bagasse LHV of 7,540 kJ/kg and that of fuel oil 41, 840 kJ/kg, and taking 90%as oil-burning boiler efficiency, 5.95 kg of bagasse would replace 1 kg of oil. The Kyoto Mechanism defines CO₂ generation by fuel oil as 2.65 kg per liter. Using 0.85for the specific gravity of fuel oil, the amount of CO₂ generation will be 3.12 kg-CO₂/kg. Therefore, CO₂reduction per ton of bagasse in terms of fuel oil will be: 3.12/5.95 =0.524 kg-CO₂/kg-bagasse. As 1 kg of bagasse generates 2 kg of steam, the CO₂reduction of a 100t/h steam boiler will be112,660 ton/year for an annual operation of4,300 hours, as follows. 0.524 × 100/2 = 26.2 t-CO₂/h, 26.2 × 4,300 =112,660 t-CO₂/year. This revised version was published online in August 2006 with corrections to the Cover Date.     

中国核电能源链的生命周期温室气体排放研究

应用全能源链分析(PCA)和生命周期分析(LCA)方法,采用第一手调查数据和一些新的参数,对我国核电能源链的生命周期温室气体排放进行评价计算.结果表明,现阶段我国核电能源链(包括核燃料循环前段、核电站)的实际温室气体排放量为6.2g CO2,eq/(k W·h),若考虑核燃料循环后段(乏燃料后处理与废物处置)则总的温室气体排放量为11.9g CO2,eq/(k W·h).核电是低碳能源,发展核电代替一定规模的煤电提供一次能源,每1k W·h电力生产能够减排大约1kg二氧化碳.推进核电产业链的技术升级和持续节能降耗,鼓励材料再循环再利用,核电能源链的温室气体排放仍有进一步降低的空间.     

Water and wastewater eco-efficiency indicators for the sugar cane industry

The consumption of large volumes of water and the generation of organic compounds as liquid effluents are major environmental problems in sugar cane processing industry. The volume of freshwater required by this industry can be significantly reduced by recovering the intrinsic water present in sugar cane. This amount of freshwater will depend on the process technology. Three new indices for sugar cane plants are introduced in this work: WIN, which indicates the efficiency of water use, and EIN1 and EIN2, which quantify Chemical Oxygen Demand of wastewater. Selected case studies illustrate the advantages of employing these indices as guides for the selection among process design alternatives that account for environmental performance.     

Global warming contributions from wheat,sheep meat and wool production in Victoria,Australia – a life cycle assessment

This paper compares the life cycle global warming potential of three of Australia’s important agricultural production activities – the production of wheat, meat and wool in grazed subterranean clover (sub-clover) dominant pasture and mixed pasture (perennial ryegrass/phalaris/sub-clover/grass and cape weed) systems. Two major stages are presented in this life cycle assessment (LCA) analysis: pre-farm, and on-farm. The pre-farm stage includes greenhouse gas (GHG) emissions from agricultural machinery, fertilizer, and pesticide production and the emissions from the transportation of these inputs to paddock. The on-farm stage includes GHG emissions due to diesel use in on-farm transport and processing (e.g. seeding, spraying, harvesting, topdressing, sheep shearing), and non-CO₂ (nitrous oxide (N₂O), and methane (CH₄)) emissions from pastures and crop grazing of lambs.The functional unit of this life cycle analysis is the GHG emissions (carbon dioxide equivalents – CO₂ -e) from 1 kg of wheat, sheep meat and wool produced from sub-clover, wheat and mixed pasture plots. The GHG emissions (e.g. CO₂, N₂O and CH₄ emission) from the production, transportation and use of inputs (e.g. fertilizer, pesticide, farm machinery operation) during pre-farm and on-farm stages are also included. The life cycle GHG emissions of 1 kg of wool is significantly higher than that of wheat and sheep meat. The LCA analysis identified that the on-farm stage contributed the most significant portion of total GHG emissions from the production of wheat, sheep meat and wool. This LCA analysis also identified that CH₄ emissions from enteric methane production and from the decomposition of manure accounted for a significant portion of the total emissions from sub-clover and mixed pasture production, whilst N₂O emissions from the soil have been found to be the major source of GHG emissions from wheat production.     

基于投入产出法的北京能源消耗温室气体排放清单分析

城市是一个巨大能源物资消耗体和温室气体排放体,相关研究受到广泛关注.本文以2007年为例基于投入产出法研究北京市能源消耗的温室气体排放量,计算得出CH4和N2O这两种常规温室气体排放量.结果表明,北京市2007年能源消耗温室气体排放量为3531.72万tCO2当量,其中CO2排放量为3514.40万t,CH4排放量为1734.32t,N2O排放量为435.83t.北京市工业部门仍然是主要的温室气体排放部门,其排放的温室气体占CO2总量的98.96%,CH4总量的88.48%和N2O总量的98.99%.不同最终使用部门中,政府部门消费产生的温室气体排放量超过总量的15%,高于城镇消费和农村消费之和;调出和出口部门的碳排放量超过总量的40%,所占比例最大.贸易中,隐含在调出和出口部门中温室气体排放量是隐含在调入和进口部门的十几倍.北京市不同行业的温室气体排放强度略优于全国水平.降低北京市温室气体排放量可从进一步优化产业结构,发挥科技减排的作用,提高不同产业的能源利用率等方面采取措施.