考虑可再生性的燃料生命周期净能源成本优化

提出了一个新的考虑燃料可再生性的净能源成本指标.这一指标除了燃料的净能源产出和气态污染物排放外部成本之外,还将生命周期成本和燃料可再生性综合成一个指标,而已往的研究一般仅考虑前两项.以广西木薯-汽油混合燃料考虑可再生性的生命周期净能源成本优化为案例,对木薯乙醇-汽油混合燃料考虑可再生性的生命周期净能源成本指标进行了优化.结果表明：与初始值相比,优化后该指标值降低6.9%.     

考虑可再生性的全生命周期净能源成本评估方法研究

提出了一个新的考虑燃料可再生性的净能源成本指标。这一指标将燃料的净能源产出、气态污染物排放外部成本、生命周期成本和能源可再生性综合成一个统一的指标，燃料指标值越低表明燃料的总体表现越好。运用该指标对木薯乙醇——汽油混合燃料和传统汽油燃料分别进行了评估。结果表明与分别评价燃料的净能源产出、生命周期成本、排放和可再生性指标比较，为考虑燃料的可再生性的全生命周期净能源成本指标提供了一个区别燃料优劣的有力手段。     

Energy balance and GHG-abatement cost of cassava utilization for fuel ethanol in Thailand

Since 2001, in order to enhance ethanol's cost competitiveness with gasoline, the Thai government has approved the exemption of excise tax imposed on ethanol, controlling the retail price of gasohol (a mixture of ethanol and gasoline at a ratio of 1:9) to be less than that of octane 95 gasoline, within a range not exceeding 1.5 baht a litre. The policy to promote ethanol for transport is being supported by its positive effects on energy security and climate change mitigation. An analysis of energy, greenhouse gas (GHG) balances and GHG abatement cost was done to evaluate fuel ethanol produced from cassava in Thailand. Positive energy balance of 22.4 MJ/L and net avoided GHG emission of 1.6 kg CO₂ eq./L found for cassava-based ethanol (CE) proved that it would be a good substitute for gasoline, effective in fossil energy saving and GHG reduction. With a GHG abatement cost of US$99 per tonne of CO₂, CE is rather less cost effective than the many other climate strategies relevant to Thailand in the short term. Opportunities for improvements are discussed to make CE a reasonable option for national climate policy.     

木薯乙醇汽油生命周期能源、环境及经济性评价

建立了木薯乙醇汽油生命周期能源、环境和经济性评价模型，并对木薯乙醇汽油进行了生命周期能源、环境及经济性评价。结果表明：与普通汽油比较，木薯乙醇汽油生命周期整体能源消耗升高，石油消耗降低；生命周期温室气体、VOC和CO等污染物排放降低；销售价格升高并需要政府补贴。从平衡生命周期能源消耗、环境排放和经济性角度出发，木薯乙醇汽油可以在广西推广使用。     

燃料乙醇生命周期影响评价

建立了中国燃料乙醇生命周期影响评价模型,并以木薯燃料乙醇为例,对中国燃料乙醇进行了生命周期影响评价。结果表明：在木薯燃料乙醇生命周期过程中,“燃烧／车辆使用”产生的环境影响最大,占整个生命周期的51．82％;其次为“燃料生产”单元,占41．32％;“原料生产”单元仅占6．86％。随着木薯燃料乙醇在汽油中混合比例的增加,其生命周期环境影响总水平值降低。与汽油比较,木薯乙醇产生的环境影响较小。     

燃料乙醇能源系统的生态重组

以木薯为原料的燃料乙醇传统生产模式是农业和工业两个简单线性过程的叠加,资源消耗量大,排放废物多。根据工业生态学原理,借鉴自然生态系统的模式对该过程进行生态重组,通过引入分解者及消费者,使物质、能量在系统内循环成为可能,系统呈现复杂化趋势,形成工、农业共生体。经生态重组后,系统产生的可燃气自给有余,年产燃料乙醇2.5万t的系统副产物可饲养生猪5.0万头、产有机肥料30.0万t、可降解塑料5.4万t;年可减排CO2 2.4万t,处理废液34.0万t、木薯茎秆等农业废弃物22.7万t,额外创造16亿元经济收入,节约生产成本550万元。     

木薯乙醇-汽油混合燃料生命周期能源消耗多目标优化研究

建立了木薯乙醇—汽油混合燃料生命周期能源消耗单目标和多目标优化模型。以生命周期总体能源消耗、化石燃料消耗和石油消耗为优化目标，对木薯乙醇—汽油混合燃料生命周期能源消耗进行了单目标及多目标优化，并进行了灵敏度分析。结果表明：多目标优化能使木薯乙醇—汽油混合燃料的生命周期总体能源、化石燃料和石油消耗同时降低，可以为木薯乙醇—汽油混合燃料的应用提供决策依据，具有重要的应用价值。     

Hydrogen–ethanol blending as an alternative fuel of spark ignition engines

The performance and pollutant emission of a four-stroke spark ignition engine using hydrogen–ethanol blends as fuel have been studied. The tests were performed using 2, 4, 6, 8, 10 and 12 mass% hydrogen–ethanol blends. Gasoline fuel was used as a basis for comparison. The effect of using different blends of hydrogen–ethanol on engine power, specific fuel consumption, CO and NO_x emission was studied. Operating test results for a range of compression ratio (CR) and equivalent ratio are presented. The results show that the supplemental hydrogen in the ethanol–air mixture improves the combustion process and hence improves the combustion efficiency, expands the range of combustibility of the ethanol fuel, increases the power, reduces the s.f.c., and reduces toxic emissions. The important improvement of hydrogen addition is to reduce the s.f.c. of ethanol engines. Results were compared to those with gasoline fuel at 7 CR and stoichiometric equivalence ratio.     

Economics, environment, and energy life cycle assessment of automobiles fueled by bio-ethanol blends in China

This study examines the life cycle economics, environment impacts, and energy consumptions of Chinese automobiles fueled by bio-ethanol blends, utilizing life cycle assessment (LCA) techniques, and puts forward C, Env, En, EEE indicators to assess the economics, combined environmental impacts, energy consumption, and the balance of the three, as a means to evaluate whether the energy utilization efficiency and the domestic environment improvement are achieved at the lowest cost possible. A generic gasoline fueled car is used as a baseline case, and the cassava-based E85 fueled FFV in Guangxi is used as a case study. On the life cycle basis, the cost of cassava-based E85 fueled FFV is about 15% higher than that of gasoline fueled car, of which the two key factors are the price of cassava and gasoline, through a cost breakdown analysis. It also has lower life-cycle emissions of CO₂, CO, HC, and PM pollutants, higher NO_X emissions, while about 20% combined environment indicator is lower than that of the gasoline fueled car. And, it is higher in total energy consumption, lower in fossil fuels and petroleum consumptions, and has a better combined energy indicator. Lastly, the EEE indicator of the cassava-based E85 fueled FFV is about 29% less than that of the gasoline fueled car. Hence, E85 fueled FFV is a better vehicle than the gasoline fueled car, taking the balance of all the 3 “E”s, the energy, environmental and economical aspects, into considerations.     

Simulation-based life cycle assessment of energy efficiency of biomass-based ethanol fuel from different feedstocks in China

Interests in biomass-based fuel ethanol (BFE) have been re-boosted due to oil shortage and environmental deterioration. Biomass-based fuel ethanol is renewable and, apparently, environmentally friendly. Biomass-based E10 (a blend of 10% ethanol and 90% gasoline by volume) is a promising conventional gasoline substitute, because vehicle engines require no modifications to run on E10 and vehicle warranties are unaffected. This paper presented life cycle assessments (LCAs) of energy efficiency of wheat-based E10 from central China, corn-based E10 from northeast China, and cassava-based E10 from southwest China. The respective energy flow-based evaluation model of wheat-, corn-, and cassava-based E10 was built based on data from pilot BFE plants. Monte Carlo method is applied to deal with the uncertain parameters and input and output variables of the evaluation model because of its wide application and easy development of statistical dispersion of calculated quantities. According to the assessment results, the average energy input/output ratio of wheat-based fuel ethanol (WFE), corn-based fuel ethanol (CFE), and cassava-based fuel ethanol (KFE) is 0.70, 0.75, and 0.54, respectively, and biomass-based E10 vehicle can have less fossil energy demand than gasoline-fueled ones.     

CO2 emissions from the production and combustion of fuel ethanol from corn

Concern over the increasing concentration of CO₂ in the Earth's atmosphere is causing us to re-evaluate how we use energy. In particular, we need to inquire if there are alternative energy systems which discharge less net CO₂ per unit of energy service. This paper deals with the CO₂ fluxes associated with the use of one biomass fuel, ethanol derived from corn. In a sustainable agricultural system, there is no net CO₂ flux to the atmosphere from the corn itself but there is a net CO₂ flux due to the fossil-fuel supplements currently used to produce and process corn. A comparison between ethanol from corn and gasoline from crude oil becomes very complex because of the variability of corn yield, the lack of available data on corn processing, and the complexity of treating the multiple products from corn processing. When the comparison is made on an energy content basis only, with no consideration of how the products are to be used, and at the margin of the current U.S. energy system, it appears that there is a net CO₂ saving associated with ethanol from corn. This net saving in CO₂ emissions may be as large as 40% or as small as 20%, depending on how one chooses to evaluate the by-product credits. This analysis also demonstrates that the frequently posed question, whether the energy inputs to ethanol exceed the energy outputs, would not be an over-riding consideration even if it were true, because most of the inputs are as coal and natural gas, whereas the output is as a high-quality liquid fuel.     

Performance and exhaust emissions of a gasoline engine with ethanol blended gasoline fuels using artificial neural network

The purpose of this study is to experimentally analyse the performance and the pollutant emissions of a four-stroke SI engine operating on ethanol–gasoline blends of 0%, 5%, 10%, 15% and 20% with the aid of artificial neural network (ANN). The properties of bioethanol were measured based on American Society for Testing and Materials (ASTM) standards. The experimental results revealed that using ethanol–gasoline blended fuels increased the power and torque output of the engine marginally. For ethanol blends it was found that the brake specific fuel consumption (bsfc) was decreased while the brake thermal efficiency (η_b.th.) and the volumetric efficiency (η_v) were increased. The concentration of CO and HC emissions in the exhaust pipe were measured and found to be decreased when ethanol blends were introduced. This was due to the high oxygen percentage in the ethanol. In contrast, the concentration of CO₂ and NO_x was found to be increased when ethanol is introduced. An ANN model was developed to predict a correlation between brake power, torque, brake specific fuel consumption, brake thermal efficiency, volumetric efficiency and emission components using different gasoline–ethanol blends and speeds as inputs data. About 70% of the total experimental data were used for training purposes, while the 30% were used for testing. A standard Back-Propagation algorithm for the engine was used in this model. A multi layer perception network (MLP) was used for nonlinear mapping between the input and the output parameters. It was observed that the ANN model can predict engine performance and exhaust emissions with correlation coefficient (R) in the range of 0.97–1. Mean relative errors (MRE) values were in the range of 0.46–5.57%, while root mean square errors (RMSE) were found to be very low. This study demonstrates that ANN approach can be used to accurately predict the SI engine performance and emissions.     

Aerobic biodegradation of butanol and gasoline blends

This work aimed to assess the aerobic biodegradation of butanol/gasoline blends (5; 10; 15 and 20% v/v), being the latter compared to the ethanol/gasoline blend (20% v/v). Two experimental techniques were employed, namely the respirometric method and the redox indicator DCPIP test. In the former, experiments simulating the contamination of natural environments (addition of 50 mL of fuel kg⁻¹ of soil from a non-contaminated site and 20 mL of fuel L⁻¹ of water from a river) were carried out in biometer flasks (250 mL), used to measure the microbial CO₂ production. The DCPIP test assessed the capability of four inocula to biodegrade the blends of 20%. The addition of butanol at different concentrations enhanced the biodegradation of gasoline in soil. However, no practical gains were observed for concentrations of butanol above 10%. Ethanol showed to have a much faster biodegradation rate than butanol, particularly in water, and the following order of biodegradability was found: ethanol > butanol > gasoline. The addition of the alcohols to the gasoline resulted in positive synergic effects on the biodegradation of the fuels in soil and water matrices. Furthermore, results suggest that, in soil, butanol better enhanced the biodegradation of gasoline than ethanol.     

A new future for carbohydrate fuel cells

The development of renewable energy sources to reduce our dependence on limiting fossil fuel reserves continues to be a critical research initiative. Utilizing the abundant high energy content of carbohydrates contained in biomass (cellulose and hemicellulose) must be considered to be an important contribution to our overall energy budget. Carbohydrate-derived furan-based liquid fuels and especially ethanol are becoming important added components forming gasoline blends to lower overall fossil fuel use. Alternate renewable energy processes that more efficiently use the carbohydrate energy content are desirable and would lower the overall carbohydrate input requirement for energy production. Recently, new catalysts have shown the feasibility of efficiently transporting the 24 electrons in glucose to fuel cell electrodes making possible the direct conversion of the stored energy in carbohydrates into electricity with the benign formation of carbonate and water as products. The conversion of glycerol, a byproduct of biodiesel production, into three-carbon carbohydrates provides another opportunity to produce electricity from an abundant carbohydrate source. New developments in catalyst systems promise to make carbohydrate fuel cells an important part of future energy strategies.     

Full chain energy analysis of fuel ethanol from cane molasses in Thailand

An analysis of energy performance and supply potential was performed to evaluate molasses utilization for fuel ethanol in Thailand. The Thai government recently has set up a production target of 1.925 million litres a day of sugar-based ethanol. The molasses-based ethanol (MoE) system involves three main segments: sugar cane cultivation, molasses generation, and ethanol conversion. Negative net energy value found for MoE is a consequence of not utilizing system co-products (e.g. stillage and cane trash) for energy. Taking into account only fossil fuel or petroleum inputs in the production cycle, the energy analysis provides results in favour of ethanol. A positive net energy of 5.95 MJ/L which corresponds to 39% energy gain shows that MoE is efficient as far as its potential to replace fossil fuels is concerned. Another encouraging result is that each MJ of petroleum inputs can produce 6.12 MJ of ethanol fuel. Regarding supply potential, if only the surplus molasses is utilized for ethanol, a shift of 8–10% sugar cane produce to fuel ethanol from its current use in sugar industry could be a probable solution.     

我国生物燃料乙醇产业新进展

燃料乙醇产业发展近20年来,为支持国家三农事业、改善大气环境、减少原油进口做出多重贡献。近年来,在国家政策推动下,我国生物燃料乙醇产业引起各界高度关注。产业链相关的生产企业、科研机构、石化和汽车行业等从不同视角做了大量实践和研究。本文从生物燃料乙醇技术进步、炼油产业的关联效应、对汽车行业的影响三方面进行概述,分析当前发展生物燃料乙醇产业呈现的新趋势。技术进步方面,从研究到生产实际,已更多地着眼于开发多种原料灵活加工的方式,构建新的产品结构,并采用技术手段降低过程能耗、发掘净能量提升空间、降低生产成本,开辟纤维素乙醇技术的新途径;此外,在产品转化率的科学评价方式、建立可持续综合效益评估模型以及设计新型对称双阴极结构解决乙醇燃料电池稳定性问题有更深入的研究。炼油产业关联效应方面,大量研究分析了油品升级、乙醇的加入对尾气污染物排放的影响;而燃料乙醇对炼油行业的影响涉及油库的改造、对组分油品质的要求、产品结构优化等诸多层面。汽车行业对新燃料系统的关注度也在不断提高,在乙醇汽油的燃烧效率、喷射策略和非常规污染物排放控制等方面有新的方案和比较。整体产业链的研发活力不断加强,正带动产业向着高质量方向发展。     

Environmental profile of ethanol from poplar biomass as transport fuel in Southern Europe

Liquid biofuels provide one of the few options for fossil fuel substitution in the short to medium-term and they are strongly being promoted by the European Union as transport fuel (such as ethanol) since they have the potential to offer both greenhouse gas (GHG) savings and energy security. A “well to wheel” analysis has been conducted for poplar based ethanol by means of the Life Cycle Assessment (LCA) approach. The aim of the analysis is to assess the environmental performance of three ethanol applications (E10, E85 and E100) in comparison with conventional gasoline. To compare the environmental profiles, the study addressed the impact potentials per kilometre driven by a middle size passenger car, taking into account the performance difference between ethanol blends and gasoline. According to the results of this study, fuel ethanol derived from poplar biomass may help to reduce the contributions to global warming, abiotic resources depletion and ozone layer depletion up to 62%, 72% and 36% respectively. Reductions of fossil fuel extraction of up to 80% could be achieved when pure ethanol is used. On the contrary, contributions to other impact categories would be increased, specifically to acidification and eutrophication. In both categories, ethanol based blends are less environmentally friendly than conventional gasoline due to the higher impact from the upstream activities. Research focussed on the reduction of the environmental impacts should be pointed forward poplar cultivation as well as ethanol conversion plant (enzyme manufacturing, energy production and distillation). In this study poplar cultivation was really intensive in order to obtain a high yield. Strategic planning according to the location of the crops and its requirements should help to reduce these impacts from its cultivation.     

Emergy analysis of cassava-based fuel ethanol in China

Emergy analysis considers both energy quality and energy used in the past, and compensates for the inability of money to value non-market inputs in an objective manner. Its common unit allows all resources to be compared on a fair basis. As feedstock for fuel ethanol, cassava has some advantages over other feedstocks. The production system of cassava-based fuel ethanol (CFE) was evaluated by emergy analysis. The emergy indices for the system of cassava-based fuel ethanol (CFE) are as follows: transformity is 1.10 E + 5 sej/J, EYR is 1.07, ELR is 2.55, RER is 0.28, and ESI is 0.42. Compared with the emergy indices of wheat ethanol and corn ethanol, CFE is the most sustainable. CFE is a good alternative to substitute for oil in China. Non-renewable purchased emergy accounts for 71.15% of the whole input emergy. The dependence on non-renewable energy increases environmental degradation, making the system less sustainable relative to systems more dependent on renewable energies. For sustainable development, it is vital to reduce the consumption of non-renewable energy in the production of CFE.     

Life cycle simulation-based economic and risk assessment of biomass-based fuel ethanol (BFE) projects in different feedstock planting areas

Increasing attention is being paid to biomass-based fuel ethanol (BFE) for its contributions to moderating oil crisis, reducing environmental impact, and promoting local economy. This paper aims to assess and compare the economic viabilities and investment risks of three BFE projects in different feedstock planting areas in China. Internal cost models of wheat-based fuel ethanol (WFE) in Central China, corn-based fuel ethanol (CFE) in Northeast China, and cassava-based fuel ethanol (KFE) in Southwest China are developed. The projects’ net cash flow (NCF) and net present values (NPV) are pursued by internal cost model simulation with the Monte Carlo method. According to the simulation results, KFE project is economically viable for its positive expected NPV and its expected internal rate of return (IRR) (12%), while CFE and WFE are not economically viable for their negative expected NPVs. Sensitivity analysis is performed to find out the key determinants of the projects’ expected NPVs and to evaluate their future economic viabilities. The analysis results indicate that CFE has better potential to become economically viable comparing to WFE project. Possible measures to improve the expected NPV of CFE are then proposed.     

Energy and greenhouse gas balances of cassava-based ethanol

Biofuel production has been promoted to save fossil fuels and reduce greenhouse gas (GHG) emissions. However, there have been concerns about the potential of biofuel to improve energy efficiency and mitigate climate change. This paper investigates energy efficiency and GHG emission saving of cassava-based ethanol as energy for transportation. Energy and GHG balances are calculated for a functional unit of 1 km of road transportation using life-cycle assessment and considering effects of land use change (LUC). Based on a case study in Vietnam, the results show that the energy input for and GHG emissions from ethanol production are 0.93 MJ and 34.95 g carbon dioxide equivalent per megajoule of ethanol respectively. The use of E5 and E10 as a substitute for gasoline results in energy savings, provided that their fuel consumption in terms of liter per kilometer of transportation is not exceeding the consumption of gasoline per kilometer by more than 2.4% and 4.5% respectively. It will reduce GHG emissions, provided that the fuel consumption of E5 and E10 is not exceeding the consumption of gasoline per kilometer by more than 3.8% and 7.8% respectively. The quantitative effects depend on the efficiency in production and on the fuel efficiency of E5 and E10. The variations in results of energy input and GHG emissions in the ethanol production among studies are due to differences in coverage of effects of LUC, CO₂ photosynthesis of cassava, yields of cassava, energy efficiency in farming, and by-product analyses.