Reducing greenhouse gas emissions from magnesium die casting

The U.S. magnesium industry uses sulfur hexafluoride (SF₆) as a cover gas to prevent the rapid and hazardous oxidation of molten magnesium. While this gas is considered to be safe and effective in this application, it is one of the most potent and persistent greenhouse gases (GHG) found in the atmosphere. The U.S. Environmental Protection Agency (EPA) launched a collaborative initiative called the SF₆ Emission Reduction Partnership for the Magnesium Industry in 1999 to identify and implement practical technologies for improving the industry's environmental profile. EPA's Partners, joined by the International Magnesium Association (IMA), have voluntarily committed to eliminate the use of SF₆ by 2010. The Partnership and IMA's commitment sent a clear signal to industry suppliers and has precipitated the exploration of alternate cover gases that are just as effective as SF₆ but greatly reduce the process's climate impact. The focus of this study is to assess byproducts, degradation levels, and GHG emission factors for three different fluorinated cover gases (SF₆, AM-cover™, and Novec™ 612) in cold chamber die casting applications. The results of this study are used to describe two approaches that modify current Intergovernmental Panel on Climate Change (IPCC) Good Practice Guidance for estimating cover gas emissions from the magnesium industry.     

Reduction of urban heat island and associated greenhouse gas emissions

Mitigation and Adaptation Strategies for Global Change - The reduction of urban heat island (UHI) and carbon emission is of great importance for thermal environment of urban residential areas. This...     

Opportunities to reduce greenhouse gas emissions from households in Nigeria

Efforts to mitigate climate threats should not exclude the household as the household is a major driver of greenhouse gas (GHG) emissions through its consumption patterns. This paper derives an emission index that could be used to estimate inventories of carbon dioxide (CO₂) emissions from kerosene combustion for lighting in Nigeria and also looks at the implications of solar pv lighting replacing kerosene lamp in Nigeria. Findings indicate that (1) average CO₂ emissions from kerosene combustion for lighting in Nigeria is about 0.06 kg per hour per lamp, which can be taken as the kerosene lamp CO₂ emission index for Nigeria. (2) about 3 × 10W_p solar pv will be required to replace a kerosene lamp, while about 0.124 tonnes of CO₂ will be avoided per lamp per year, operating at 6 h daily. At the national level, under the kerosene lamp replacement projection assumptions made, between 0.4 and 1.0 million tonnes of CO₂ will be avoided per year. The household investment required to owe a solar pv, including the capital cost of switching from kerosene lamp, is about US356, while the national capital investment outlay is between 1,138.265 and US356, while the national capital investment outlay is between 1,138.265 and US2,848 million. (3) Certified Emission Reduction (CER) units, assuming CO₂ is traded, will generate significant annual revenues on the order of 6.96 to almost US17.4 million per year, while earnings from unspent household kerosene fuel could amount to between 2,520 and US17.4 million per year, while earnings from unspent household kerosene fuel could amount to between 2,520 and US6,300 million over the life span of the solar pv. The micro-economic assessment carried out indicates the non-attractiveness of solar pv use at the household level, and (4) to promote solar pv use, both long and short term policy measures that aim at cost reduction were suggested. The paper concludes that, factoring the suggested measures into the climate, energy, and financial policy decision discourse in Nigeria could empower the households to play a significant role in achieving global CO₂ emission reduction, but at the local level.     

Mitigation of greenhouse gas emissions by anaerobic digestion of cattle slurry

Biogas treatment of animal manures is an upcoming technology because it is a way of producing renewable energy (biogas). However, little is known about effects of this management strategy on greenhouse gas (GHG) emissions during fermentation, storage, and field application of the substrates compared to untreated slurries. In this study, we compared cattle slurry and cattle slurry with potato starch as additive during the process of fermentation, during storage and after field application. The addition of potato starch strongly enhanced CH₄ production from 4230 l CH₄ m⁻³ to 8625 l CH₄ m⁻³ in the fermenter at a hydraulic retention time (HRT) of 29 days. Extending the HRT to 56 days had only a small effect on the CH₄ production. Methane emissions from stored slurry depended on storage temperature and were highest from unfermented slurry followed by the slurry/starch mixture. Gas emissions from untreated and fermented slurry during storage were further analyzed in a pilot-scale experiment with different levels of covering such as straw cover, a wooden lid and no cover. Emissions of greenhouse gases (CH₄, N₂O, NH₃) were in the range of 14.3–17.1 kg CO₂ eq. m⁻³ during winter (100 day storage period) and 40.5–90.5 kg CO₂ eq. m⁻³ during summer (140 day storage period). A straw cover reduced NH₃ losses, but not overall GHG emissions, whereas a solid cover reduced CH₄ and NH₃ emissions. After field application, there were no significant differences between slurry types in GHG emissions (4.15–8.12 kg CO₂ eq. m⁻³ a⁻¹). GHG emissions from slurry stores were more important than emissions after field application. Co-digestion of slurry with additives such as starch has a large potential to substitute fossil energy by biogas. On a biogas plant, slurry stores should be covered gas-tight in order to eliminate GHG emissions and collect CH₄ for electricity production.     

Integrated scenario modelling of energy,greenhouse gas emissions and forestry

Preventing dangerous climate change requires actions on several sectors. Mitigation strategies have focused primarily on energy, because fossil fuels are the main source of global anthropogenic greenhouse gas emissions. Another important sector recently gaining more attention is the forest sector. Deforestation is responsible for approximately one fifth of the global emissions, while growing forests sequester and store significant amounts of carbon. Because energy and forest sectors and climate change are highly interlinked, their interactions need to be analysed in an integrated framework in order to better understand the consequences of different actions and policies, and find the most effective means to reduce emissions. This paper presents a model, which integrates energy use, forests and greenhouse gas emissions and describes the most important linkages between them. The model is applied for the case of Finland, where integrated analyses are of particular importance due to the abundant forest resources, major forest carbon sink and strong linkage with the energy sector. However, the results and their implications are discussed in a broader perspective. The results demonstrate how full integration of all net emissions into climate policy could increase the economic efficiency of climate change mitigation. Our numerical scenarios showed that enhancing forest carbon sinks would be a more cost-efficient mitigation strategy than using forests for bioenergy production, which would imply a lower sink. However, as forest carbon stock projections involve large uncertainties, their full integration to emission targets can introduce new and notable risks for mitigation strategies.     

High-resolution spatial distribution of greenhouse gas emissions in the residential sector

The development of high-resolution greenhouse gas (GHG) inventories is an important step towards emission reduction in different sectors. However, most of the spatially explicit approaches that have been developed to date produce outputs at a coarse resolution or do not disaggregate the data by sector. In this study, we present a methodology for assessing GHG emissions from the residential sector by settlements at a fine spatial resolution. In many countries, statistical data about fossil fuel consumption is only available at the regional or country levels. For this reason, we assess energy demand for cooking and water and space heating for each settlement, which we use as a proxy to disaggregate regional fossil fuel consumption data. As energy demand for space heating depends heavily on climatic conditions, we use the heating degree day method to account for this phenomenon. We also take the availability of energy sources and differences in consumption patterns between urban and rural areas into account. Based on the disaggregated data, we assess GHG emissions at the settlement level using country and regional specific coefficients for Poland and Ukraine, two neighboring countries with different energy usage patterns. In addition, we estimate uncertainties in the results using a Monte Carlo method, which takes uncertainties in the statistical data, calorific values, and emission factors into account. We use detailed data on natural gas consumption in Poland and biomass consumption for several regions in Ukraine to validate our approach. We also compare our results to data from the EDGAR (Emissions Database for Global Atmospheric Research), which shows high agreement in places but also demonstrates the advantage of a higher resolution GHG inventory. Overall, the results show that the approach developed here is universal and can be applied to other countries using their statistical information.

     

Modelling greenhouse gas emissions from European conventional and organic dairy farms

Agriculture is an important contributor to global emissions of greenhouse gases (GHG), in particular for methane (CH₄) and nitrous oxide (N₂O). Emissions from farms with a stock of ruminant animals are particularly high due to CH₄ emissions from enteric fermentation and manure handling, and due to the intensive nitrogen (N) cycle on such farms leading to direct and indirect N₂O emissions. The whole-farm model, FarmGHG, was designed to quantify the flows of carbon (C) and nitrogen (N) on dairy farms. The aim of the model was to allow quantification of effects of management practices and mitigation options on GHG emissions. The model provides assessments of emissions from both the production unit and the pre-chains. However, the model does not quantify changes in soil C storage.Model dairy farms were defined within five European agro-ecological zones for both organic and conventional systems. The model farms were all defined to have the same utilised agricultural area (50 ha). Cows on conventional and organic model farms were defined to achieve the same milk yield, so the basic difference between conventional and organic farms was expressed in the livestock density. The organic farms were defined to be 100% self-sufficient with respect to feed. The conventional farms, on the other hand, import concentrates as supplementary feed and their livestock density was defined to be 75% higher than the organic farm density. Regional differences between farms were expressed in the milk yield, the crop rotations, and the cow housing system and manure management method most common to each region.The model results showed that the emissions at farm level could be related to either the farm N surplus or the farm N efficiency. The farm N surplus appeared to be a good proxy for GHG emissions per unit of land area. The GHG emissions increased from 3.0 Mg CO₂-eq ha⁻¹ year⁻¹ at a N surplus of 56 kg N ha⁻¹ year⁻¹ to 15.9 Mg CO₂-eq ha⁻¹ year⁻¹ at a N surplus of 319 kg N ha⁻¹ year⁻¹. The farm N surplus can relatively easily be determined on practical farms from the farm records of imports and exports and the composition of the crop rotation. The GHG emissions per product unit (milk or metabolic energy) were quite closely related to the farm N efficiency, and a doubling of the N efficiency from 12.5 to 25% reduced the emissions per product unit by ca. 50%. The farm N efficiency may therefore be used as a proxy for comparing the efficiencies of farms with respect to supplying products with a low GHG emission.     

Livestock-related greenhouse gas emissions: impacts and options for policy makers

Research shows that livestock account for a significant proportion of greenhouse gas (GHG) emissions and global consumption of livestock products is growing rapidly. This paper reviews the life cycle analysis (LCA) approach to quantifying these emissions and argues that, given the dynamic complexity of our food system, it offers a limited understanding of livestock's GHG impacts. It is argued that LCA's conclusions need rather to be considered within a broader conceptual framework that incorporates three key additional perspectives. The first is an understanding of the indirect second order effects of livestock production on land use change and associated CO₂ emissions. The second compares the opportunity cost of using land and resources to rear animals with their use for other food or non-food purposes. The third perspective is need—the paper considers how far people need livestock products at all. These perspectives are used as lenses through which to explore both the impacts of livestock production and the mitigation approaches that are being proposed. The discussion is then broadened to consider whether it is possible to substantially reduce livestock emissions through technological measures alone, or whether reductions in livestock consumption will additionally be required. The paper argues for policy strategies that explicitly combine GHG mitigation with measures to improve food security and concludes with suggestions for further research.     

Estimation of greenhouse gas emissions in China and the abatement measures

The major emission sources of carbon dioxide, methane, nitrous oxide and CFCs in China have been identified, and the emission trends has been estimated. Besides fossil fuel combustion, human respiration and biomass burning are important sources. Some feasible abatement measures on energy conservation, afforestation and biomass recycling have been discussed.     

中国温室气体排放增长的结构分解分析

利用结构分解分析(SDA)的加权平均分解法分析了4类增长因素对1992~2007年中国温室气体排放变化的影响.结果表明:总体上,最终需求规模扩大是引起排放增长的主要因素,其次是投入产出结构的改变,温室气体排放强度降低是减缓排放量的主要因素,最终需求结构改变对排放量变化的影响不明显.从部门角度看,建筑业和机械、电气、电子设备制造业是隐含温室气体排放增加的主要来源.从变化趋势看,2002~2007年温室气体排放增幅明显高于其他时期,出口和固定资本形成的大幅增长是推动这一时期排放增长的主要原因.     

Mitigation of greenhouse gas emissions in European conventional and organic dairy farming

Dairy farming is the largest agricultural source of the greenhouse gases methane (CH₄) and nitrous oxide (N₂O) in Europe. A whole-farm modeling approach was used to investigate promising mitigation measures. The effects of potential mitigation measures were modeled to obtain estimates of net greenhouse gas (GHG) emissions from representative dairy model farms in five European regions. The potential to reduce farm GHG emissions was calculated per kg milk to compare organic and conventional production systems and to investigate region and system specific differences. An optimized lifetime efficiency of dairy cows reduced GHG emissions by up to 13% compared to baseline model farms. The evaluation of frequent removal of manure from animal housing into outside covered storage reduced farm GHG emissions by up to 7.1%. Scraping of fouled surfaces per se was not an effective option since the reduction in GHG emissions from animal housing was more than out-weighed by increased emissions from the storage and after field application. Manure application by trail hose and injection, respectively, was found to reduce farm GHG emissions on average by 0.7 and 3.2% compared to broadcasting. The calculated model scenarios for anaerobic digestion demonstrated that biogas production could be a very efficient and cost-effective option to reduce GHG emissions. The efficiency of this mitigation measure depends on the amount and quality of organic matter used for co-digestion, and how much of the thermal energy produced is exploited. A reduction of GHG emissions by up to 96% was observed when all thermal energy produced was used to substitute fossil fuels. Potential measures and strategies were scaled up to the level of European regions to estimate their overall mitigation potential. The mitigation potential of different strategies based on a combination of measures ranged from −25 up to −105% compared to baseline model farms. A full implementation of the most effective strategy could result in a total GHG emission reduction of about 50 Mt of carbon dioxide (CO₂) equivalents per year for conventional dairy farms of EU(15) comparable to the defined model farms.     

我国饮食结构变化对农业温室气体排放的影响

从食物消费端入手,研究饮食结构变化对农业温室气体排放的影响.研究显示我国食物消费呈现出动物性食物替代粮食消费的趋势,动物性食物的温室气体排放系数是植物性食物的7倍以上.1990~2010年人均食物消费相关的温室气体排放增长了39%,肉类消费已成为食物消费中最大的温室气体排放来源,且还将持续增长.当我国人均收入达到2010年美国水平时,世界平均肉类消费水平、高肉类消费水平、低肉类消费水平和营养均衡消费水平四种情景下,人均肉类消费的温室气体排放将比2010年分别增长47.8%、119.9%、4.8%、-29.6%.我国食物消费应当提倡在保障均衡营养摄入的前提下,适当减少肉类消费,达到温室气体减排、资源节约、污染减排的协同效应.     

Does the Swedish consumer's choice of food influence greenhouse gas emissions?

Consumer's choice of food can influence the environment. In Sweden, in common with many other countries, consumers need to be given information so they can make environmentally informed shopping choices. However, what is the most advantageous dietary choice to lower greenhouse emissions? This study investigates the greenhouse gas emissions associated with food production for food consumed in Sweden annually. Specifically, this study compares greenhouse gas emissions associated with a nutritionally and environmentally sustainable diet with the average consumption of food in Sweden 1999. The study concludes that the change in energy use and greenhouse gas emission associated with this change of diet is negligible. Lowering greenhouse gas emissions by changing food production processes results in more profound changes than teaching consumers to make environmentally correct choices. There is a basic need for a reduction or a replacement of the use of fossil fuels to produce and distribute our food in order to reach any significant reduction in the emission of greenhouse gases. Swedish agricultural policy does not provide ways to reduce greenhouse gas emissions. In Sweden therefore there is an immediate need to design policy instruments with the primary aim of reducing the greenhouse effect.     

Earth observations for estimating greenhouse gas emissions from deforestation in developing countries

In response to the United Nations Framework Convention on Climate Change (UNFCCC) process investigating the technical issues surrounding the ability to reduce greenhouse gas (GHG) emissions from deforestation in developing countries, this paper reviews technical capabilities for monitoring deforestation and estimating emissions. Implementation of policies to reduce emissions from deforestation require effective deforestation monitoring systems that are reproducible, provide consistent results, meet standards for mapping accuracy, and can be implemented at the national level. Remotely sensed data supported by ground observations are key to effective monitoring. Capacity in developing countries for deforestation monitoring is well-advanced in a few countries and is a feasible goal in most others. Data sources exist to determine base periods in the 1990s as historical reference points. Forest degradation (e.g. from high impact logging and fragmentation) also contribute to greenhouse gas emissions but it is more technically challenging to measure than deforestation. Data on carbon stocks, which are needed to estimate emissions, cannot currently be observed directly over large areas with remote sensing. Guidelines for carbon accounting from deforestation exist and are available in approved Intergovernmental Panel on Climate Change (IPCC) reports and can be applied at national scales in the absence of forest inventory or other data. Key constraints for implementing programs to monitor greenhouse gas emissions from deforestation are international commitment of resources to increase capacity, coordination of observations to ensure pan-tropical coverage, access to free or low-cost data, and standard and consensual protocols for data interpretation and analysis.     

The analysis of greenhouse gas emissions/reductions in waste sector in Vietnam

The global waste sector produces, on average, 2–5 % of global anthropogenic greenhouse gas (GHG) emissions. The amount of GHG emissions has grown steadily and is predicted to increase considerable in the forthcoming decades because of the increases in population and gross domestic product (GDP). However, the GHG mitigation opportunities for the sector are still fully not exploited, in particularly in developing countries. A series of initiatives were highly successful and showed that large reductions in emissions are possible. This study aims to propose a holistic quantification model, which can be used for estimation of waste generation and evaluation of the potential reduction of GHG emissions in waste sector for developing countries with a particular application to Vietnam. The two scenarios set for the study were business as usual (BaU) which waste management is assumed to follow past and current trends and CounterMeasure (CM) which alternative waste treatment and management are assessed. Total emissions in the BaU scenario are projected to increase from 29.47 MtCO₂eq in 2010 to 85.60 MtCO₂eq by 2030 and 176.32 MtCO₂eq by 2050. The highest emissions are due to methane (CH₄) released by disposal sites, accounting for about 60 % of the GHG emissions from waste in Vietnam in 2030. This emission is projected to increase significantly (67 % in 2050), unless more of the methane is captured and used for energy generation. The CM scenario gives emission reductions from 25.7 % (2020), 40.5 % (2030) to 56.6 % (2050) compared to the BaU scenario. The highest GHG reduction is achieved through recycling, followed by methane recovery to optimize the co-benefit for climate change mitigation.     

Review of greenhouse gas emissions from crop production systems and fertilizer management effects

Fertilizer nitrogen (N) use is expanding globally to satisfy food, fiber, and fuel demands of a growing world population. Fertilizer consumers are being asked to improve N use efficiency through better management in their fields, to protect water resources and to minimize greenhouse gas (GHG) emissions, while sustaining soil resources and providing a healthy economy. A review of the available science on the effects of N source, rate, timing, and placement, in combination with other cropping and tillage practices, on GHG emissions was conducted. Implementation of intensive crop management practices, using principles of ecological intensification to enhance efficient and effective nutrient uptake while achieving high yields, was identified as a principal way to achieve reductions in GHG emissions while meeting production demands. Many studies identified through the review involved measurements of GHG emissions over several weeks to a few months, which greatly limit the ability to accurately determine system-level management effects on net global warming potential. The current science indicates: (1) appropriate fertilizer N use helps increase biomass production necessary to help restore and maintain soil organic carbon (SOC) levels; (2) best management practices (BMPs) for fertilizer N play a large role in minimizing residual soil nitrate, which helps lower the risk of increased nitrous oxide (N₂O) emissions; (3) tillage practices that reduce soil disturbance and maintain crop residue on the soil surface can increase SOC levels, but usually only if crop productivity is maintained or increased; (4) differences among fertilizer N sources in N₂O emissions depend on site- and weather-specific conditions; and (5) intensive crop management systems do not necessarily increase GHG emissions per unit of crop or food production; they can help spare natural areas from conversion to cropland and allow conversion of selected lands to forests for GHG mitigation, while supplying the world's need for food, fiber, and biofuel. Transfer of the information to fertilizer dealers, crop advisers, farmers, and agricultural and environmental authorities should lead to increased implementation of fertilizer BMPs, and help to reduce confusion over the role of fertilizer N on cropping system emissions of GHGs. Gaps in scientific understanding were identified and will require the collaborative attention of agronomists, soil scientists, ecologists, and environmental authorities in serving the immediate and long-term interests of the human population.     

广东省居民生活直接能源消费大气污染物与温室气体排放趋势研究

居民生活直接能源消费是重要的大气污染物和温室气体排放来源,识别其历史排放趋势是科学制定管控策略的基础.然而目前我国尚缺乏省级尺度居民生活能源消费排放趋势的研究.以广东省为研究对象,通过广泛收集居民生活直接能源消费数据和排放因子,建立了2006—2017年广东省居民生活直接能源消费大气污染物和温室气体排放清单,并采用情景分析法量化了能源结构变化对居民生活直接能源消费大气污染物与温室气体排放的影响.结果表明：①2006—2017年居民生活直接能源消费排放的大气污染物和温室气体均呈下降趋势,CO、PM_2.5、BC、OC、CH₄、CO₂和N₂O排放量分别下降70%、59%、59%、66%、77%、30%和73%;②城乡贡献上,乡村居民生活直接能源消费是大气 污染物和温室气体排放的主要来源,排放分担率分别在70%和60%以上;③空间分布上,2017年广东省居民生活直接能源消费大气污染物和温室气体排放主要集中在粤东、粤西传统燃料消费量较高的地区,以及广州、东莞和深圳等人口密度较大的城市地区;④能源结构清洁化所致的2006—2017年广东省居民生活直接能源消费大气污染物和温室气体减排比例为38%~88%;⑤以2025年为目标年,居民生活能源结构持续清洁化发展能够进一步降低居民生活直接能源消费大气污染物和温室气体排放,尤其对CO、PM_2.5、BC、CH₄和N₂O的减排比例均在80%以上.     

冷凝水回流对堆肥腐熟度和污染气体排放影响

为探究堆肥过程中高温水蒸气携带的冷凝水回流对腐熟度及温室气体排放的影响,本文以猪粪和厨余垃圾为堆肥原料,在60L密闭好氧堆肥反应器中进行48d的高温好氧堆肥实验.结果表明,堆肥高温期产生的饱和水蒸汽因发酵罐封闭体系不能及时排出,会在发酵罐壁形成冷凝水回流入堆体中,整个堆肥过程冷凝水产率为物料湿重的18%.此外,回流冷凝水中主要成分为NH₄⁺-N(11.40g/L)、溶解性有机碳(6.3g/L)以及无机盐离子,具有较高的EC值(41.05mS/cm)和pH值(9.22),而较高的NH₄⁺-N含量使冷凝水回流处理的堆肥产品种子发芽指数(GI)略达到腐熟(71.4%),与排出处理相比GI下降了25.5%.同时,冷凝水回流使NH₃和CH₄排放量分别增加了55.2%的60.2%,但是CO₂和N₂O排放量分别降低了16.8%的34.8%.研究表明,冷凝水回流可降低17.8%总温室效应.本文建议堆肥过程将高温水蒸气冷凝排出,一...