Greenhouse gas emission inventory for Senegal, 1991

The first greenhouse gas (GHG) emission estimates for Senegal, for the year 1991, were produced according to the draft IPCC/OECD guidelines for national inventories of GHGs. Despite certain discrepancies, nonavailability of data, the quality of some of the data collected, and the methodology, the estimates provide a provisional basis for Senegal to fulfill its obligations under the UN Framework Convention on Climate Change. This inventory reveals that GHG emissions in Senegal, like those in many developing countries, can mainly be attributed to the use of biomass for energy, land-use change and forestry, and savanna burning. Taking into account the direct global warming potential of the main GHGs (CO₂, CH₄, and N₂O), Senegal's emissions are estimated at 17.6 Tg ECO₂. The major gases emitted are CO₂ (61% of GHG emissions), followed by CH₄ (35%) and N₂O (4%). Energy accounts for 45% of total emissions (12% from fossil energy and 33% from traditional biomass energy); land-use change and forests, 18%; agriculture, 24%; waste, 12%; and industry, 1%.     

Modeling biogeochemistry and forest management practices for assessing GHGs mitigation strategies in forested wetlands

Despite the importance of forested wetland in the global carbon cycle, no widely applicable ecosystem model exists for this ecosystem. This study reports the linkage between Wetland-DNDC and MIKE SHE for carbon dynamics and GHGs mitigation strategies analyses in forested wetland. Wetland-DNDC was modified by parameterizing forest management practices and refining anaerobic biogeochemical processes. Mortality due to senescence was estimated as a function of tree age or as a function of the relative biomass. We used a harvesting damage mortality coefficient as a linear function of time with three parameters: Initial mortality, Duration of the damage and Intensity of the initial harvesting. The model was validated against experimental data obtained from the GNF site near Florida. As a preliminary application, we simulated the effect of water table position and forest management practices on GHGs emissions and carbon dynamics to test the capabilities of the models for simulating seasonal and long-term carbon budget in forested wetland.     

Availability of disaggregated greenhouse gas emissions from beef cattle production: A systematic review

Agriculture is a significant source of anthropogenic greenhouse gas (GHG) emissions, and beef cattle are particularly emissions intensive. GHG emissions are typically expressed as a carbon dioxide equivalent (CO₂e) ‘carbon footprint’ per unit output. The 100-year Global Warming Potential (GWP₁₀₀) is the most commonly used CO₂e metric, but others have also been proposed, and there is no universal reason to prefer GWP₁₀₀ over alternative metrics. The weightings assigned to non-CO₂ GHGs can differ significantly depending on the metric used, and relying upon a single metric can obscure important differences in the climate impacts of different GHGs. This loss of detail is especially relevant to beef production systems, as the majority of GHG emissions (as conventionally reported) are in the form of methane (CH₄) and nitrous oxide (N₂O), rather than CO₂. This paper presents a systematic literature review of harmonised cradle to farm-gate beef carbon footprints from bottom-up studies on individual or representative systems, collecting the emissions data for each separate GHG, rather than a single CO₂e value. Disaggregated GHG emissions could not be obtained for the majority of studies, highlighting the loss of information resulting from the standard reporting of total GWP₁₀₀ CO₂e alone. Where individual GHG compositions were available, significant variation was found for all gases. A comparison of grass fed and non-grass fed beef production systems was used to illustrate dynamics that are not sufficiently captured through a single CO₂e footprint. Few clear trends emerged between the two dietary groups, but there was a non-significant indication that under GWP₁₀₀ non-grass fed systems generally appear more emissions efficient, but under an alternative metric, the 100-year global temperature potential (GTP₁₀₀), grass-fed beef had lower footprints. Despite recent focus on agricultural emissions, this review concludes there are insufficient data available to fully address important questions regarding the climate impacts of agricultural production, and calls for researchers to include separate GHG emissions in addition to aggregated CO₂e footprints.     

The Kyoto Protocol and non-CO2 Greenhouse Gases and Carbon Sinks

Many trace constituents other than carbon dioxide affect the radiative budget of the atmosphere. The existing international agreement to limit greenhouse gases, the Kyoto Protocol, includes carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF₆) and credit for some carbon sinks. We investigate technological options for reducing emissions of these gases and the economic implications of including other greenhouse gases and sinks in the climate change control policy. We conduct an integreated assessment of costs using the MIT Emissions Prediction and Policy Analysis (EPPA) model combined with estimates of abatement costs for non-CO₂ greenhouse gases and sinks. We find that failure to take advantage of the other gas and sink flexibility would nearly double aggregate Annex B costs. Including all the GHGs and sinks is actually cheaper than if only CO₂ had been included in the Protocol and their inclusion achieves greater overall abatement. There remains considerable uncertainty in these estimates, the magnitude of the savings depends heavily on reference projections of emissions, for example, but these uncertainties do not change the overall conclusion that non-CO₂ GHGs are an important part of a climate control policy.     

北京市废弃物处理温室气体排放特征

基于《2006年IPCC国家温室气体清单指南》推荐的方法,结合《省级温室气体清单编制指南（试行）》和《城市温室气体核算工具指南》的部分数据与核算范围,针对固体废弃物填埋、焚烧和废水处理等过程,核算了北京市2005-2014年废弃物处理过程中温室气体总排放量。结果表明：2005-2014年北京市废弃物处理过程温室气体总排放量呈逐渐上升趋势,2014年温室气体总排放量比2005年增长98%。10年间,固体废弃物填埋过程一直是最主要的温室气体排放源,到2014年排放量达到最大,为416.3×10⁴t二氧化碳当量（CO₂e）。废弃物填埋、废水处理和废弃物焚烧过程占总排放量的比例分别为78.5%（CO₂e质量分数,下同）、13.5%和8%。结合已有研究,系统优化国内7个典型城市废弃物处理温室气体排放因子,核算7个城市排放情况,并对比分析了北京市排放情况。     

基于卫星遥感的中国东部地区NO2减排成效验证

基于Aura卫星臭氧监测仪（OMI）数据，分析了2011—2018年中国东部地区对流层NO₂柱浓度的时空分布规律，以广泛而客观地验证NO₂减排成效。结果表明：进入"十二五"以来，中国东部地区对流层NO₂柱浓度快速下降，高值区域范围快速收缩甚至消失；华北平原、长江中下游平原污染相对严重，同时这些地区污染程度正在得到较快速的缓解；京津冀、长三角、珠三角是中国东部地区对流层NO₂柱浓度相对最高、下降速度最快的典型区域；中国东部地区NO₂减排取得的成效与产业转型升级、能源结构调整及严控移动源排放等政策措施密不可分。     

Modelling and assessing inter-regional trade of CO2 emission reduction units

A cost-efficient way to allocate carbon dioxide (CO₂) emission reductions among countries or regions is to harmonise their marginal reduction costs. This could be achieved by a market of emission reduction units (ERUs). To model such a market, we use a multi-regional MARKAL-MACRO model. It gives insights into the consequences of co-ordinating CO₂ abatement on regional energy systems and economies. As a numerical application, we assess the establishment of a market of ERUs among three European countries for curbing their CO₂ emissions.     

电力跨区域调配隐含的污染转移效应

为研究中国30个省/自治区/直辖市之间电力区域调配的污染物转移效应,构建了电力传输的污染转移模型,并以SO_2和NO_x为例对2006、2015年数据进行测算。结果表明,2015年电力行业SO_2、NO_x排放强度分别由2006年的4.03、2.18 g/(kW·h)下降到0.69、0.77 g/(kW·h)。2015年,16个电力净输入区通过电力跨区域传输的SO_2、NO_x转移量分别为47.8×10~4、53.0×10~4t,占这些地区电力行业SO_2、NO_x排放量的24.1%、24.2%;14个电力净输出区通过电力跨区域传输的SO_2、NO_x转移量分别为-54.6×10~4、-52.1×10~4t,占这些地区电力行业SO_2、NO_x排放量的26.5%、22.8%。研究结果对于分析区域物质流动所隐含的污染流动,全面认识区域污染物排放格局,制定合理的区域污染减排目标具有一定借鉴意义。     

Marginal Abatement Costs and Marginal Welfare Costs for Greenhouse Gas Emissions Reductions: Results from the EPPA Model

Marginal abatement cost (MAC) curves, relationships between tonnes of emissions abated and the CO₂ (or greenhouse gas (GHG)) price, have been widely used as pedagogic devices to illustrate simple economic concepts such as the benefits of emissions trading. They have also been used to produce reduced-form models to examine situations where solving the more complex model underlying the MAC is difficult. Some important issues arise in such applications: (1) Are MAC relationships independent of what happens in other regions?, (2) are MACs stable through time regardless of what policies have been implemented in the past?, and (3) can one approximate welfare costs from MACs? This paper explores the basic characteristics of MAC and marginal welfare cost (MWC) curves, deriving them using the MIT Emissions Prediction and Policy Analysis model. We find that, depending on the method used to construct them, MACs are affected by policies abroad. They are also dependent on policies in place in the past and depend on whether they are CO₂-only or include all GHGs. Further, we find that MACs are, in general, not closely related to MWCs and therefore should not be used to derive estimates of welfare change. We also show that, as commonly constructed, MACs may be unreliable in replicating results of the parent model when used to simulate GHG policies. This is especially true if the policy simulations differ from the conditions under which the MACs were simulated.     

Organic Liquids Storage Tanks Volatile Organic Compounds (VOCS) Emissions Dispersion and Risk Assessment in Developing Countries: The Case of Dar-Es-Salaam City, Tanzania

The emission estimation of nine volatile organic compounds (VOCs) from eight organic liquids storage tanks companies in Dar-es-Salaam City Tanzania has been done by using US EPA standard regulatory storage tanks emission model (TANKS 4.9b). Total VOCs atmospheric emission has been established to be 853.20 metric tones/yr. It has been established further that petrol storage tanks contribute about 87% of total VOCs emitted, while tanks for other refined products and crude oil were emitting 10% and 3% of VOCs respectively. Of the eight sources (companies), the highest emission value from a single source was 233,222.94 kg/yr and the lowest single source emission value was 6881.87 kg/yr. The total VOCs emissions estimated for each of the eight sources were found to be higher than the standard level of 40,000 kg/yr per source for minor source according to US EPA except for two sources, which were emitting VOCs below the standard level. The annual emissions per single source for each of the VOCs were found to be below the US EPA emissions standard which is 2,000~kg/yr in all companies except the emission of hexane from company F1 which was slightly higher than the standard. The type of tanks used seems to significantly influence the emission rate. Vertical fixed roof tanks (VFRT) emit a lot more than externally floating roof tanks (EFRT) and internally floating roof tanks (IFRT). The use of IFRT and EFRT should be encouraged especially for storage of petrol which had highest atmospheric emission contribution. Model predicted atmospheric emissions are less than annual losses measured by companies in all the eight sources. It is possible that there are other routes for losses beside atmospheric emissions. It is therefore important that waste reduction efforts in these companies are directed not only to reducing atmospheric emissions, but also prevention of the spillage and leakage of stored liquid and curbing of the frequently reported illegal siphoning of stored products. Emission rates for benzene, toluene, and xylene were used as input to CALPUFF air dispersion model for the calculation of spatial downwind concentrations from area sources. By using global positioning system (GPS) and geographical information system (GIS) the spatial benzene concentration contributed by organic liquid storage tanks has been mapped for Dar-es-Salaam City. Highest concentrations for all the three toxic pollutants were observed at Kigamboni area, possibly because the area is located at the wind prevailing direction from the locations of the storage tanks. The model predicted concentrations downwind from the sources were below tolerable concentrations by WHO and US-OSHA. The highest 24 hrs averaging time benzene concentration was used for risk assessment in order to determine maximum carcinogenic risk amongst the population exposed at downwind. Established risk for adult and children at 2.9×10^-3 and 1.9×10^-3 respectively, are higher than the acceptable US-EPA risk of 1×10^-6. It is very likely that the actual VOCs concentrations in some urban areas in Tanzania including Dar-es-Salaam City are much higher than the levels reported in this study when other sources such as petrol stations and motor vehicles on the roads are considered. Tanzania Government therefore need to put in place: an air quality policy and legislation, establish air quality guidelines and acquire facilities which will enable the implementation of air quality monitoring and management programmes.     

Can buildings sector achieve the carbon mitigation ambitious goal: Case study for a low-carbon demonstration city in China?

China is committed to peaking its carbon emissions by 2030 and become a carbon-neutral society by 2060. The building sector that accounts for over one-third of the total carbon emissions is expected to face a great challenge in helping China achieve this goal. Shenzhen, as a low-carbon pilot city, whether its low-carbon work of urban buildings reaches the target is crucial. An attempt has been made in this study to assess the intensity of carbon emissions and associated reduction efficiency of urban buildings (operation stage) in Shenzhen by using the life cycle assessment method. The results show that the total carbon emissions generated from the buildings' operation stage have increased from 22 million metric tons (Mt) CO₂eq in 2005 to 42 (±13%) Mt. CO₂eq in 2019. Carbon emissions mainly result from the buildings' electricity use (79%), followed by refrigerant release emissions (12%). The energy conservation and carbon emissions reduction intensity in Shenzhen is at the middle level in China, and there is considerable space for improvement. According to scenario-based analysis, the carbon emission of the buildings sector can probably reach its peak by 2025 with the implementation of suitable policies – 5 years earlier than national target by 2030. Overall, this study makes a systemic analysis of the characteristics of urban buildings energy consumption and carbon emissions reduction, which can provide supportings for justifying the effectiveness of low-carbon activities in Shenzhen and beyond.     

G20峰会期间长三角区域臭氧变化及管控效果评估

为了研究2016年二十国集团领导人峰会(G20峰会)期间长三角区域臭氧(O3)变化特征,评估管控措施对O3浓度的影响,利用2016年8月10日至9月20日杭州及周边地区的空气质量监测数据、气象数据以及排放清单数据,分析了O3和NO2浓度及气象条件的时空分布特征,研究了不同管控区域不同保障时期O3浓度的时空变化和O3敏感控制区的改变。结果表明:峰会保障期间对于一次排放污染物和细颗粒物的管控措施效果明显,但核心区的O3质量浓度高于严控区和管控区,分别高出11. 2、9. 2μg/m^3。日间的NOx管控导致O3日变化幅度增高接近50μg/m^3。在峰会保障期间,卫星数据和站点观测结果显示核心区O3由VOCs控制区转为NOx-VOCs协同控制区,整个长三角区域的O3生成对于NOx排放量更为敏感。管控措施越强,核心区的O3生成对于NOx排放越敏感,且O3浓度与NOx浓度的相关性越强。对NOx和VOCs的协同控制降低排放,是关系O3浓度管控的一项重要工作。     

Reduction of SO2 Emissions by Ammonia Gas During Staged Combustion

To reduce SO2 emissions, ammonia gas was injected into a coal-fired fluidized-bed combustor under staged commbustion condition. The combustor was 2 m high with a 30 cm static bed height and a freeboard height of 170 cm. The ammonia gas was injected at 52 cm and 65 cm above the distributor, which had a temperature of ca. 700 °C, by an uncooled stainless-steel tube injector. The experiments investigated the effects of ammonia gas injection on sulphur dioxide emissions at staged conditions, varying the: (i) excess air level, (ii) secondary air ratio, (iii) fluidizing velocity, (iv) ammonia injection position, and (v) the ammonia : sulphur dioxide molar ratio.A maximum reduction of 66% in SO2 emissions was found at 40% excess air, 65 : 35 staging, 1.5 m/s fluidizing velocity, 65 cm injection height, and an NH3 : SO2 molar ratio of 1.2. The onset of SO2 reduction occurred at an NH3 : SO2 ratio of 0.5. The fluidizing velocity, excess air, level of staging, and ammonia injection height all have a significant influence on SO2 reduction.It is difficult to determine how the SO2 reduction varies with the operating conditions when ammonia is injected in the high temperature zone of the combustor. As sulphur oxides-ammonia reactions are low temperature reactions, the findings confirm the occurrence of reactions above the freeboard or near the exit to the cyclone.     

Analysis of acidic components, heavy metals and PAHS of particulate in the Changwon–Masan area of Korea

This study is an analysis of the concentrations and components of heavy metals in PM_2.5 and the total suspended particulate (TSP) collected at a mechanical industrial complex (IC) site in Changwon and at a residential site in Masan, Korea. Particulate was collected during two sampling periods, from the late summer to the early fall and from the middle to late fall, at the IC site and one sampling period, from the middle fall to the early winter, at the residential site. PM_2.5 and TSP samples were taken by an annular denuder system and a hi-volume air sampler, respectively. The authors also identified the concentrations and components of heavy metals extracted from the PM_2.5 and TSP filters, the acidic components extracted from the PM_2.5 filters, and the polycyclic aromatic hydrocarbons (PAHs) extracted from polyurethane foam (PUF) plug. The average concentrations of the PM_2.5 collected at the IC and residential sites were very similar. Major sources of PM_2.5 at the study sites, however, were air emissions from vehicles and industry as well as emissions from residential heating and soil origins, respectively. The higher concentrations of the TSP at the IC site, as compared to those at the residential site, were due to either increased suspended dust from vehicle emissions or re-suspended road dust because of increased vehicle speeds near the IC site. Heavy metal concentrations in the TSPs were higher than those in the PM_2.5. The heavy metal concentrations in the PM_2.5 and TSP at the IC site with heavy traffic were substantially greater than those at the residential site. The concentrations of TSP and heavy metals and PAHs in PM during the period of the middle to late fall was much higher than those during the period of the late summer to early fall at the IC site. This is because of the difference in meteorological characteristics and energy uses between two periods. The residential site also showed higher concentrations of acidic anions while the IC site showed higher concentrations of acidic cation. Secondary aerosols or particulates, such as ammonium nitrate or ammonium nitrite, might have been important constituents of the PM_2.5 at the residential site. The PAHs in the TSP collected at the IC site was greatly affected by traffic and industry emissions consisting mostly of high molecular weight PAHs with two to four rings. PAHs in the TSP at the site, however, were affected by residential heating and air emissions from small chemical plants having higher concentrations of low molecular weight PAHs with five to six rings.     

Estimating the mitigation potential of the Chinese service sector using embodied carbon emissions accounting

It is universally recognized that direct carbon emissions based on energy consumption and industrial production lead to carbon leakage and inequality. This paper employs input–output analysis (IOA) and the hypothetical extraction method (HEM) to establish an embodied carbon analysis framework to resolve the above externalities. As a typical downstream consumption industry, the service sector has had very little work examining its embodied carbon transfer structure and related climate policies. In this paper, carbon flows of China's service sector between 1997 and 2015 are mapped and a scenario analysis is conducted that accounts for the service sector development plan and carbon emissions reduction targets. The results demonstrate that 13–19% of carbon flows in the Chinese economy are caused by the service sector's demand of other sectors. Controlling the industry scale and carbon intensity of its upstream industries effectively mitigates the dramatic growth of embodied carbon emissions in the service sector. The embodied carbon emissions accounting framework might provide new insights for the definition of emissions reduction responsibility on both a regional and sectoral scale. The further exploration of the service industry from this novel perspective will be helpful in realizing China's overall carbon emissions reduction goals.     

Assessment of the Health Impacts of Particulates from the Redevelopment of Kings Cross

The Kings Cross/St. Pancras area has been a rail transport hub from Central London to the Midlands and North Eastern England since the middle of the nineteenth century and dust from the Kings Cross railway lands was even described by Charles Dickens.¹ The Channel Tunnel high speed Rail Link (CTRL) is being constructed between 2001 and 2007 to connect continental Europe to Central London. The CTRL and associated development will help regenerate an area that is surrounded by deprived high density housing estates. London Borough of Camden has set up an extensive particulate monitoring programme to determine if there are any health impacts on local residents from emissions from the demolition and construction work. This article assesses the results from particulate measurements in 2003–2004 and compares this to baseline conditions before the redevelopment work began. The evidence suggests that although 2003 had higher than average pollution levels in the UK as a whole, even higher levels of particulates in the size range PM₁₀–PM_2.5 (defined as PM_coarse) were measured in Kings Cross. Due to the size of these particulates, they tend to be released from construction works rather than transport or secondary particulate sources. Concentrations in 2004 were lower than 2003, but this was primarily due to meteorological conditions. The paper also looks at the health of the local population and discusses whether these elevated levels are creating a problem and legally constitute a statutory nuisance. The Council continues to work with the contractors to try and ensure best practical means to minimise dust emissions and their effect on local residents. ¹Our Mutual Friend     

Current status and perspectives of accelerated carbonation processes on municipal waste combustion residues

The increasing volumes of municipal solid waste produced worldwide are encouraging the development of processes to reduce the environmental impact of this waste stream. Combustion technology can facilitate volume reduction of up to 90%, with the inorganic contaminants being captured in furnace bottom ash, and fly ash/APC residues. The disposal or reuse of these residues is however governed by the potential release of constituent contaminants into the environment. Accelerated carbonation has been shown to have a potential for improving the chemical stability and leaching behaviour of both bottom ash and fly ash/APC residues. However, the efficacy of carbonation depends on whether the method of gas application is direct or indirect. Also important are the mineralogy, chemistry and physical properties of the fresh ash, the carbonation reaction conditions such as temperature, contact time, CO₂ partial pressure and relative humidity. This paper reviews the main issues pertaining to the application of accelerated carbonation to municipal waste combustion residues to elucidate the potential benefits on the stabilization of such residues and for reducing CO₂ emissions. In particular, the modification of ash properties that occur upon carbonation and the CO₂ sequestration potential possible under different conditions are discussed. Although accelerated carbonation is a developing technology, it could be introduced in new incinerator facilities as a “finishing step” for both ash treatment and reduction of CO₂ emissions.     

重点区域生活垃圾焚烧行业实施大气污染物超低排放的可行性技术路线研究

随着中国城镇化建设进程的不断加快,生活垃圾焚烧行业迅猛发展。在钢铁、焦化以及燃煤电厂等行业已实施超低排放的情况下,推行生活垃圾焚烧行业超低排放,对进一步改善大气环境具有积极意义。国内一些省份和城市已经或者正在制定生活垃圾焚烧行业地方标准,积极推动行业污染物超低排放。笔者结合各地经验,探讨了4种不同技术方式、不同运行成本的超低排放可行性技术路线,为重点区域垃圾焚烧实施超低排放提供参考和依据。     

大气14CO2的加速器质谱分析技术研究进展

利用加速器质谱技术测定大气¹⁴CO₂以示踪大气化石源CO₂成为当前减污降碳工作的热点。该文从加速器质谱¹⁴C分析基础出发,系统介绍了加速器质谱的工作原理、大气样品的采集及纯化、石墨化样品的制备和测定,阐述了大气碳监测领域14 CO₂测试的研究进展。随着加速器质谱技术的不断发展,大气¹⁴CO₂的研究将会更加广泛和深入,有助于进一步认识大气化石源CO₂的来源,更有针对性地开展减污降碳工作。未来应统一制定¹⁴CO₂监测方法标准,规范操作流程和质控手段,完善实验仪器配套设施,加快提升监测能力和水平。     

A comparison of emission calculations using different modeled indicators with 1-year online measurements

The overall measurement of farm level greenhouse gas (GHG) emissions in dairy production is not feasible, from either an engineering or administrative point of view. Instead, computational model systems are used to generate emission inventories, demanding a validation by measurement data. This paper tests the GHG calculation of the dairy farm-level optimization model DAIRYDYN, including methane (CH₄) from enteric fermentation and managed manure. The model involves four emission calculation procedures (indicators), differing in the aggregation level of relevant input variables. The corresponding emission factors used by the indicators range from default per cow (activity level) emissions up to emission factors based on feed intake, manure amount, and milk production intensity. For validation of the CH₄ accounting of the model, 1-year CH₄ measurements of an experimental free-stall dairy farm in Germany are compared to model simulation results. An advantage of this interdisciplinary study is given by the correspondence of the model parameterization and simulation horizon with the experimental farm’s characteristics and measurement period. The results clarify that modeled emission inventories (2,898, 4,637, 4,247, and 3,600 kg CO₂-eq. cow^?1 year^?1) lead to more or less good approximations of online measurements (average 3,845 kg CO₂-eq. cow^?1 year^?1 (±275 owing to manure management)) depending on the indicator utilized. The more farm-specific characteristics are used by the GHG indicator; the lower is the bias of the modeled emissions. Results underline that an accurate emission calculation procedure should capture differences in energy intake, owing to milk production intensity as well as manure storage time. Despite the differences between indicator estimates, the deviation of modeled GHGs using detailed indicators in DAIRYDYN from on-farm measurements is relatively low (between ?6.4 % and 10.5 %), compared with findings from the literature.