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%.     

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.     

Greenhouse gas savings potential of sugar cane bio-energy systems

One of the major justifications for bio-energy systems is their low greenhouse gas (GHG) emissions compared to fossil-energy ones. Transforming a sugar mill into a bio-energy plant would contribute to climate change mitigation via the extraction of renewable electricity and ethanol. This study takes the case of the sugar industry in Thailand and identifies scenario options that offer GHG reduction benefits. Improving efficiency in electricity generation from sugar cane residues e.g. excess bagasse and cane trash is such a beneficial option. Furthermore, extracting ethanol in a so-called bio-refinery, where the co-product stillage is utilized for energy, tends to magnify the potential benefit. The largest savings potential achieved with extracting ethanol from surplus sugar versus current practice in the sugar industry in Thailand amounts to 14 million tonnes CO₂e a year. This cannot be realized in practice until the carbon debt from land conversion is repaid, which takes 4.5–7 years, assuming that the land converted is grassland.     

Life cycle greenhouse gas emissions, fossil fuel demand and solar energy conversion efficiency in European bioethanol production for automotive purposes

Crop derived biofuels such as (bio)ethanol are increasingly applied for automotive purposes. They have, however, a relatively low efficiency in converting solar energy into automotive power. The outcome of life cycle studies concerning ethanol as to fossil fuel inputs and greenhouse gas emissions associated with such inputs depend strongly on the assumptions made regarding e.g. allocation, inclusion of upstream processes and estimates of environmentally relevant in- and outputs. Peer reviewed studies suggest that CO₂ emissions linked to life cycle fossil fuel input are typically about 2.1–3.0 kg CO₂ kg⁻¹ starch-derived ethanol. When biofuel production involves agricultural practices that are common in Europe there are net losses of carbon from soil and emissions of the greenhouse gas N₂O. Dependent on choices regarding allocation, they may, for wheat (starch) be in the order of 0.6–2.5 kg CO₂ equivalent kg⁻¹ of ethanol. This makes ethanol derived from starch, or sugar crops, in Europe still less attractive for mitigating climate change. In case of wheat, changes in agricultural practice may reduce or reverse carbon loss from soils. When biofuel production from crops leads to expansion of cropland while reducing forested areas or grassland, added impetus will be given to climate change.     

A life cycle comparison of greenhouse emissions for power generation from coal mining and underground coal gasification

Underground coal gasification (UCG) is an advancing technology that is receiving considerable global attention as an economic and environmentally friendly alternative for exploitation of coal deposits. UCG has the potential to decrease greenhouse gas emissions (GHG) during the development and utilization of coal resources. In this paper, the life cycle of UCG from in situ coal gasification to utilization for electricity generation is analyzed and compared with coal extraction through conventional coal mining and utilization in power plants. Four life cycle assessment models have been developed and analyzed to compare (greenhouse gas) GHG emissions of coal mining, coal gasification and power generation through conventional pulverized coal fired power plants (PCC), supercritical coal fired (SCPC) power plants, integrated gasification combined cycle plants for coal (Coal-IGCC), and combined cycle gas turbine plants for UCG (UCG-CCGT). The analysis shows that UCG is comparable to these latest technologies and in fact, the GHG emissions from UCG are about 28 % less than the conventional PCC plant. When combined with the economic superiority, UCG has a clear advantage over competing technologies. The comparison also shows that there is considerable reduction in the GHG emissions with the development of technology and improvements in generation efficiencies.     

Sustainability assessment of large-scale ethanol production from sugarcane

The present study assesses the sustainability of ethanol produced from sugarcane and examines the environmental feasibility of a large-scale production through the use of: fossil fuel embodied energy and Emergy Assessment including farm and industrial production phases. The study indicates that about 1.82 kg of topsoil eroded, 18.4 l of water and 1.52 m² of land are needed to produce 1 l of ethanol from sugarcane. Also, 0.28 kg of CO₂ is released per liter of ethanol produced. The energy content of ethanol is 8.2 times greater than the fossil-based energy required to produce it. The transformity of ethanol is about the same as those calculated for fossil fuels. The Renewability of ethanol is 30%, a very low value; other emergy indices indicate important environmental impacts as well as natural resources consumption. The results obtained indicate that sugarcane and ethanol production present low renewability when a large-scale system is adopted.     

Operational change as a profitable cleaner production tool for a brewery

The development and implementation of new procedures and operational changes in the production processes constitutes a powerful tool for the practical application of Cleaner Production in industries. In this work an operational change (new procedure) was developed for the elaboration of a type of beer which uses sugar as malt adjunct. The change consists in processing separately the three main components of the beer wort: malt extract, sugar and water, and use them properly in a different sequence than that used up to date in the traditional process. The new procedure was successfully assayed on industrial scale in Tínima brewery, located in Camagüey, Cuba, obtaining a good quality beer, technological and economical advantages with benefits for the environment, registering significant savings in energy (49%), sugar (4%), water (7%) and caustic soda (3%) consumption; and diminishing the surplus hot water (74%), waste generation (11%) and greenhouse gases emission (21%). Beer production capacity is increased also almost three times. With the application of the new technology to the Cuban beer type of 8 °P, it was achieved a total saving of US$ 481.83/1000 hL of beer produced.     

苏州市生活垃圾处理碳足迹核查

根据《PAS2050规范》的指导,结合生命周期评价技术方法和LandGEM模型,对苏州市生活垃圾填埋和焚烧处理的生命周期过程进行了碳足迹核查. 详细列出了垃圾处理过程中可能的温室气体排放源,计算各排放源的电耗或能耗,并通过与温室气体排放系数相乘最终转化为苏州市生活垃圾处理温室气体排放量. 结果表明:苏州市填埋处理1 t生活垃圾整个生命周期过程中温室气体的排放量(以CO₂当量计)为1 942.47 kg,焚烧处理为-180.87 kg. 按照目前苏州市生活垃圾处理权重进行分配,可得苏州市处理1 t生活垃圾整个生命周期过程中温室气体的排放量(以CO₂当量计)为880.80 kg. 在整个核查过程中,考虑了在填埋和焚烧处理时发电对温室气体带来的减量效应.      

Atmospheric impacts of the life cycle emissions of fuel ethanol in Brazil: based on chemical exergy

An assessment is made of the atmospheric emissions from the life cycle of fuel ethanol coupled with the cogeneration of electricity from sugarcane in Brazil. The total exergy loss from the most quantitative relevant atmospheric emission substances produced by the life cycle of fuel ethanol is 3.26E+05 kJ/t of C₂H₅OH. Compared with the chemical exergy of 1 t of ethanol (calculated as 34.56E+06 kJ), the exergy loss from the life cycle's atmospheric emission represents 1.11% of the product's exergy. The activity that most contributes to atmospheric emission chemical exergy losses is the harvesting of sugarcane through the methane emitted in burning. Suggestions for improved environmental quality and greater efficiency of the life cycle of fuel ethanol with cogenerated energy are: harvesting the sugarcane without burning, renewable fuels should be used in tractors, trucks and buses instead of fossil fuel and the transportation of products and input should be logistically optimized.     

Greenhouse gas emissions from rubber industry in Thailand

Rubber production has been taking place in Thailand for many decades. Thailand is currently the world's largest natural rubber producer. We present emissions of greenhouse gases associated with the production of fresh latex, and three primary rubber products, including concentrated latex, block rubber (STR 20), and ribbed smoked sheet (RSS) in Thailand. Besides industrial activities in the rubber mills, the agricultural activities in rubber tree plantation are taken into account. The overall emissions from the production of concentrated latex, STR 20, and RSS amount to 0.54, 0.70, and 0.64 ton CO₂-eq/ton product, respectively. This is for the case that rubber plantations have been located on cultivated lands for more than 60 years, which is current practice in most of Thailand. Emissions are largely associated with energy use and the use of synthetic fertilizers. We also quantify emissions for the case that tropical forests have been converted to rubber plantations relatively recently, which is a recent trend in Thailand. In this case the emissions are much higher because of carbon loss from land conversion: 13, 13, and 21 ton CO₂-eq/ton product for concentrated latex, STR 20, and RSS, respectively. We discuss the implications of our results for strategies to reduce greenhouse gas emissions from rubber production.     

Hydrogen and transportation: alternative scenarios

If hydrogen (H₂) is to significantly reduce greenhouse gas emissions and oil use, it needs to displace conventional transport fuels and be produced in ways that do not generate significant greenhouse gas emissions. This paper analyses alternative ways H₂ can be produced, transported and used to achieve these goals. Several H₂ scenarios are developed and compared to each other. In addition, other technology options to achieve these goals are analyzed. A full fuel cycle analysis is used to compare the energy use and carbon (C) emissions of different fuel and vehicle strategies. Fuel and vehicle costs are presented as well as cost-effectiveness estimates. Lowest hydrogen fuel costs are achieved using fossil fuels with carbon capture and storage. The fuel supply cost for a H₂ fuel cell car would be close to those for an advanced gasoline car, once a large-scale supply system has been established. Biomass, wind, nuclear and solar sources are estimated to be considerably more expensive. However fuel cells cost much more than combustion engines. When vehicle costs are considered, climate policy incentives are probably insufficient to achieve a switch to H₂. The carbon dioxide (CO₂) mitigation cost would amount to several hundred US$ per ton of CO₂. Energy security goals and the eventual need to stabilize greenhouse gas concentrations could be sufficient. Nonetheless, substantial development of related technologies, such as C capture and storage will be needed. Significant H₂ use will also require substantial market intervention during a transition period when there are too few vehicles to motivate widely available H₂ refueling.

Feasibility of husk-fuelled steam engines as prime mover of grid-connected generators under the Thai very small renewable energy power producer (VSPP) program

Rice husk generated as a by-product of rice mill processes can be utilized as an energy source for husk-fuelled rice mills. The economic evaluation of the investment of husk-fuelled steam engine rice mills, which generate mechanical energy for the direct driving of milling equipments, has previously been presented in literature. It was reported that for some particular conditions of rice mill, the investment of husk-fuelled steam engine as energy-saving technology is financially feasible. Since May 2002, electricity distributors in Thailand have allowed renewable energy producers up to 1 MW to connect their generators to the grid in order to sell surplus electricity to the grid. This arrangement creates more income opportunities for husk-fuelled steam engine owners to generate not only mechanical power for rice milling processes, but also surplus electricity for feeding onto the grid. The objective of this study is to investigate the financial feasibility of the investment in a husk-fuelled steam engine system which drives grid-connected electrical generators, reduces rice mill demand and electricity and sells surplus electricity to the grid. The technical and economic data for rice mill sizes 35, 45, 60, 95 and 120 t/d presented in this study show that the husk-fuelled steam engine system with grid-connected generators improves the economic performance of applying the system solely for the largest 120 t/d rice mills. However, the conventional husk-fuelled steam engine without electric generator gives a better economic performance of the rice mills sizes from 45 to 95 t/d.     

Carbon footprint of sugar produced from sugarcane in eastern Thailand

Carbon footprint (CFP) of sugar produced from sugarcane in eastern Thailand was estimated from greenhouse gas emissions (CO₂, CH₄, and N₂O) during the sugarcane cultivation and milling process. The use of fossil fuels, chemical and organic fertilizer and sugarcane biomass data during cultivation were collected from field surveys, questionnaires and interviews. Sugar mill emissions, fossil fuel utilization and greenhouse gas emission from wastewater treatments were included. The results show that sugar production has a carbon footprint of 0.55 kg CO₂e kg^?1 sugar. This carbon footprint was a sum of 0.49 kg CO₂e kg^?1 sugar from sugarcane cultivation and 0.06 kg CO₂e kg^?1 sugar from the milling process. For the cultivation part, most of the GHGs emissions were from fertilizer, fossil fuel use and biomass burning. The CFP in eastern Thailand is sensitive to the type of data selected for calculation and of variations of farm inputs during sugarcane cultivation. There was no significant difference of CFP among farm sizes, although small farms tended to give a relatively higher CFP than that of medium and large farms.     

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.     

北京市生活垃圾焚烧厂耗能排污特征及节能减排潜力

将生活垃圾焚烧厂从整体到局部分为场站-工艺-单元三个层次,通过现场调查,获取了北京市生活垃圾焚烧设施在2009~2011年不同层次耗能排污数据。分析表明,在焚烧工艺中焚烧单元处理单位垃圾的电耗达到60.83 kW·h,余热发电单元水耗最大,尾气处理单元的电耗和水耗相对较小。不同场站在处理单位垃圾时烟气和炉渣产量比较接近,但飞灰排放差异较大,在2.92~24.78 kg/t垃圾之间。渗沥液水量年际变化较大,水质相对稳定,MBR单元对污染物的去除效果最好,但其耗电量较大,占渗沥液处理工艺总耗电量的87.55%。焚烧工艺发电最优值为423.77 kW·h/t垃圾,产生的电能除满足自身需求外,还剩余1.8×108 kW·h的电能,可用于渗沥液处理工艺或输向场站外部。每吨渗沥液处理最多可产生中水0.962 t,全北京市每年产生中水196456 t/a,使用潜力大。     

餐饮废物制取燃料乙醇发酵条件研究

通过单因素试验选取试验因子,并根据Box-Benhnken的中心组合试验设计原理,在单因素试验基础上采用四因素三水平响应面分析法,以乙醇含量为响应值,对发酵条件进行优化.结果表明,发酵温度、发酵时间、初始pH和接种量与乙醇含量存在显著相关性.最佳发酵条件为发酵温度33.8℃、发酵时间101.5h、初始pH=4.6、接种量16.6%.通过实验室小试,在最优发酵条件下,乙醇含量可达到6.93%,乙醇发酵效果较好.还原糖利用率达到88.7%,每吨干物质原料可产192.8L乙醇.     

Substitutable biodiesel feedstocks for the UK: a review of sustainability issues with reference to the UK RTFO

The sustainability performance of five potential UK biodiesel feedstocks is reviewed and their greenhouse gas performance investigated using the carbon and sustainability reporting methods of the UK Renewable Transport Fuel Obligation (RTFO). Of the feedstocks examined, and for which the RTFO supplies default carbon intensity values, only used cooking oil has guaranteed sustainability benefits. The other feedstocks have CO₂e payback periods of 25–5503 years if grown on converted forest or grassland, yet the RTFO currently requires no guarantee that this conversion has not taken place and requires no avoidance of indirect effects. As currently designed, the RTFO risks substantial, adverse environmental effects.     

The holistic impact of integrated solid waste management on greenhouse gas emissions in Phuket

Continually increasing amounts of municipal solid waste (MSW) and the limited capacity of the existing waste management system in Phuket have led to the consideration of integrated waste management system (IWMS). Life cycle assessment (LCA) was employed to compare the greenhouse gas emissions expressed as global warming potential (GWP) of the existing waste management system (the base scenario) and other three IWMSs for Phuket MSW. Besides incineration and landfilling, the proposed scenarios include 30% source separation for recycling (scenario 2), anaerobic digestion (scenario 3) and both (scenario 4).The functional unit is set as 1 t of Phuket MSW treated. Results from the impact assessment of the base scenario shows that the net GWP is 1006 kg CO₂ equivalent. Landfilling contributes to the highest potentials of this impact. The results from a holistic comparison show that scenario 4 is the best option among all the scenarios, contributing GWP of 415 kg CO₂ eq., whereas the base scenario is the worst. The emission of greenhouse gas from landfilling is reduced by the introduction of landfill gas recovery and utilization for electricity production. By assumption, 50% recovery of landfill gas leads to the GWP reduction around 58% by total GWP of landfilling and 36% by the net GWP of the whole system in the base scenario. The study suggests that a policy that promotes source separation should be pursued, preferably combined with the application of landfill gas recovery for electricity. Policy promoting recycling is favorable over anaerobic digestion in the situation that both treatment systems could not be established at the same time. The major conclusion from the study is that results from the LCA can support Phuket Municipality for decision-making with respect to planning and optimizing IWMS. It can benefit other municipalities or policy makers to apply in their waste management projects.     

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.