Benchmarking the environmental performance of the Jatropha biodiesel system through a generic life cycle assessment

In addition to available country or site-specific life cycle studies on Jatropha biodiesel we present a generic, location-independent life cycle assessment and provide a general but in-depth analysis of the environmental performance of Jatropha biodiesel for transportation. Additionally, we assess the influence of changes in byproduct use and production chain. In our assessments, we went beyond the impact on energy requirement and global warming by including impacts on ozone layer and terrestrial acidification and eutrophication. The basic Jatropha biodiesel system consumes eight times less nonrenewable energy than conventional diesel and reduces greenhouse gas emissions by 51%. This result coincides with the lower limit of the range of reduction percentages available in literature for this system and for other liquid biofuels. The impact on the ozone layer is also lower than that provoked by fossil diesel, although eutrophication and acidification increase eight times. This study investigates the general impact trends of the Jatropha system, although not considering land-use change. The results are useful as a benchmark against which other biodiesel systems can be evaluated, to calculate repayment times for land-use change induced carbon loss or as guideline with default values for assessing the environmental performance of specific variants of the system.     

麻疯果油料的综合开发利用

随着麻疯树资源的研究逐渐深入,麻疯果油料综合利用的产业化已在实施当中。对麻疯果油料在生物燃料、生物医药、制皂和生物肥料等方面的综合开发应用,以及目前国内外麻疯果油料在生物柴油等方面的研究动态与成果作了探讨。结果表明,麻疯果油料的综合开发利用可以获取很大的经济、社会与环境收益。     

Environmental impacts of algae-derived biodiesel and bioelectricity for transportation

Algae are a widely touted source of bioenergy with high yields, appreciable lipid contents, and an ability to be cultivated on marginal land without directly competing with food crops. Nevertheless, recent work has suggested that large-scale deployment of algae bioenergy systems could have unexpectedly high environmental burdens. In this study, a "well-to-wheel" life cycle assessment was undertaken to evaluate algae's potential use as a transportation energy source for passenger vehicles. Four algae conversion pathways resulting in combinations of bioelectricity and biodiesel were assessed for several relevant nutrient procurement scenarios. Results suggest that algae-to-energy systems can be either net energy positive or negative depending on the specific combination of cultivation and conversion processes used. Conversion pathways involving direct combustion for bioelectricity production generally outperformed systems involving anaerobic digestion and biodiesel production, and they were found to generate four and fifteen times as many vehicle kilometers traveled (VKT) per hectare as switchgrass or canola, respectively. Despite this, algae systems exhibited mixed performance for environmental impacts (energy use, water use, and greenhouse gas emissions) on a "per km" basis relative to the benchmark crops. This suggests that both cultivation and conversion processes must be carefully considered to ensure the environmental viability of algae-to-energy processes.     

LCA法在木本生物柴油清洁生产评估方面的应用研究

生命周期评价(LCA)作为一种能全程评估产业链和产品环境影响、资源消耗、净能效率的重要方法,近年来得到了越来越多的关注,也开始被用于生物柴油清洁生产领域,能为产业可持续提供决策依据。对木本生物柴油的LCA体系、评估模型与方法、国内外木本生物柴油LCA研究现状进行了综述。结果显示:木本生物柴油在燃烧阶段相比石化柴油具有清洁排放的优点,但整个生命周期的排放未必清洁,主要与我国燃煤发电、化肥和辅料生产排放有关;木本生物柴油产业作为低碳产业,温室效应和能源消耗均低于石化柴油,整个生命周期中以种植和生产阶段的排放和消耗最大并针对性提出改进措施;未来我国木本生物柴油生命周期评价应通过建设产业标准数据库、更多注重不同原料不同工艺的对比评估、兼顾经济性和生态服务功能的评估进一步拓展木本生物柴油研究的深度和广度。     

Identification of 'carbon hot-spots' and quantification of GHG intensities in the biodiesel supply chain using hybrid LCA and structural path analysis

It is expected that biodiesel production in the EU will remain the dominant contributor as part of a 10% minimum binding target for biofuel in transportation fuel by 2020 within the 20% renewable energy target in the overall EU energy mix. Life cycle assessments (LCA) of biodiesel to evaluate its environmental impacts have, however, remained questionable, mainly because of the adoption of a traditional process analysis approach resulting in system boundary truncation and because of issues regarding the impacts of land use change and N(2)O emissions from fertilizer application. In this study, a hybrid LCA methodology is used to evaluate the life cycle CO(2) equivalent emissions of rape methyl ester (RME) biodiesel. The methodology uses input-output analysis to estimate upstream indirect emissions in order to complement traditional process LCA in a hybrid framework. It was estimated that traditional LCA accounted for 2.7 kg CO(2)-eq per kg of RME or 36.6% of total life cycle emissions of the RME supply chin. Further to the inclusion of upstream indirect impacts in the LCA system (which accounted for 23% of the total life cycle emissions), emissions due to direct land use change (6%) and indirect land use change (16.5%) and N(2)O emissions from fertilizer applications (17.9%) were also calculated. Structural path analysis is used to decompose upstream indirect emissions paths of the biodiesel supply chain in order to identify, quantify, and rank high carbon emissions paths or 'hot-spots' in the biodiesel supply chain. It was shown, for instance, that inputs from the 'Other Chemical Products' sector (identified as phosphoric acid, H(3)PO(4)) into the biodiesel production process represented the highest carbon emission path (or hot-spot) with 5.35% of total upstream indirect emissions of the RME biodiesel supply chain.     

Combinatorial life cycle assessment to inform process design of industrial production of algal biodiesel

The use of algae as a feedstock for biodiesel production is a rapidly growing industry, in the United States and globally. A life cycle assessment (LCA) is presented that compares various methods, either proposed or under development, for algal biodiesel to inform the most promising pathways for sustainable full-scale production. For this analysis, the system is divided into five distinct process steps: (1) microalgae cultivation, (2) harvesting and/or dewatering, (3) lipid extraction, (4) conversion (transesterification) into biodiesel, and (5) byproduct management. A number of technology options are considered for each process step and various technology combinations are assessed for their life cycle environmental impacts. The optimal option for each process step is selected yielding a best case scenario, comprised of a flat panel enclosed photobioreactor and direct transesterification of algal cells with supercritical methanol. For a functional unit of 10 GJ biodiesel, the best case production system yields a cumulative energy demand savings of more than 65 GJ, reduces water consumption by 585 m(3) and decreases greenhouse gas emissions by 86% compared to a base case scenario typical of early industrial practices, highlighting the importance of technological innovation in algae processing and providing guidance on promising production pathways.     

The greenhouse gas emissions and fossil energy requirement of bioplastics from cradle to gate of a biomass refinery

Polyhydroxyalkanoates (PHA) are promising eco-friendly bioplastics that can be produced from cellulosic ethanol biorefineries as value-added coproducts. A cradle-to-factory-gate life cycle assessment is performed with two important categories: the greenhouse gas (GHG)emissions and fossil energy requirement per kg of bioplastics produced. The analysis indicates that PHA bioplastics contribute clearly to the goal of mitigating GHG emissions with only 0.49 kg CO(2-e) being emitted from production of 1 kg of resin. Compared with 2-3 kg CO(2-e) of petrochemical counterparts, it is about 80% reduction of the global warming potential. The fossil energy requirement per kg of bioplastics is 44 MJ, lowerthan those of petrochemical counterparts (78-88 MJ/kg resin). About 62% of fossil energy is used for processing utilities and wastewater treatment, and the rest is required for raw materials in different life cycle stages.     

Biodiesel production in a semiarid environment: a life cycle assessment approach

While the use of biodiesel appears to be a promising alternative to petroleum fuel, the replacement of fossil fuel by biofuel may not bring about the intended climate cooling because of the increased soil N2O emissions due to N-fertilizer applications. Using a life cycle assessment approach, we assessed the influence of soil nitrous oxide (N2O) emissions on the life cycle global warming potential of the production and combustion of biodiesel from canola oil produced in a semiarid climate. Utilizing locally measured soil N2O emissions, rather than the Intergovernmental Panel on Climate Change (IPCC) default values, decreased greenhouse gas (GHG) emissions from the production and combustion of 1 GJ biodiesel from 63 to 37 carbon dioxide equivalents (CO2-e)/GJ. GHG were 1.1 to 2.1 times lower than those from petroleum or petroleum-based diesel depending on which soil N2O emission factors were included in the analysis. The advantages of utilizing biodiesel rapidly declined when blended with petroleum diesel. Mitigation strategies that decrease emissions from the production and application of N fertilizers may further decrease the life cycle GHG emissions in the production and combustion of biodiesel.     

Environmental implications of municipal solid waste-derived ethanol

We model a municipal solid waste (MSW)-to-ethanol facility that employs dilute acid hydrolysis and gravity pressure vessel technology and estimate life cycle energy use and air emissions. We compare our results, assuming the ethanol is utilized as E85 (blended with 15% gasoline) in a light-duty vehicle, with extant life cycle assessments of gasoline, corn-ethanol, and energy crop-cellulosic-ethanol fueled vehicles. We also compare MSW-ethanol production, as a waste management alternative, with landfilling with gas recovery options. We find that the life cycle total energy use per vehicle mile traveled for MSW-ethanol is less than that of corn-ethanol and cellulosic-ethanol; and energy use from petroleum sources for MSW-ethanol is lower than for the other fuels. MSW-ethanol use in vehicles reduces net greenhouse gas (GHG) emissions by 65% compared to gasoline, and by 58% when compared to corn-ethanol. Relative GHG performance with respect to cellulosic ethanol depends on whether MSW classification is included or not. Converting MSW to ethanol will result in net fossil energy savings of 397-1830 MJ/MT MSW compared to net fossil energy consumption of 177-577 MJ/MT MSW for landfilling. However, landfilling with LFG recovery either for flaring or for electricity production results in greater reductions in GHG emissions compared to MSW-to-ethanol conversion.     

Full chain energy analysis of fuel ethanol from cassava in Thailand

An assessment of net energy and supply potentials was performed to evaluate cassava utilization for fuel ethanol in Thailand. Just recently, the Thai government approved the construction of 12 cassava ethanol plants with the total output of 3.4 million liters per day by the next 2 years (2007 and 2008). The cassava fuel ethanol (CFE) system involves three main segments: cassava cultivation including processing, ethanol conversion, and transportation. All materials, fuels, and human labor inputs to each segment were traced back to the primary energy expense level. Positive Net Energy Value and Net Renewable Energy Value, 8.80 MJ/L and 9.15 MJ/L, respectively, found for the CFE system in Thailand proved that it is energy efficient. Without coproduct energy credits, CFE in Thailand is even more efficient than CFE in China and corn ethanol in the United States. Regarding supply potentials, about 35% of the national cassava production would be used to feed approved CFE factories. A shift of cassava to ethanol fuel rather than its current use for chip/pellet products could be a probable solution.     

小桐子生物柴油氧化前后运动黏度变化分析

以小桐子生物柴油为样品对其氧化前后的运动黏度变化和成分变化进行研究。结果表明,小桐子生物柴油的氧化安定性诱导期为4.75 h;氧化前后样品的运动黏度均随温度升高而降低,并且氧化后的样品比氧化前样品的运动黏度有所增加,温度较高时,温度变化不再是引起运动黏度变化的主导因素,拟合数据得到氧化前后的"温度-运动黏度"经验方程;氧化后的小桐子生物柴油生成较多的醇、醛、酸、酮等物质,这些物质中的极性基团与脂肪酸甲酯的酯基之间生成电偶极子和氢键,增强了分子内聚力,导致氧化后的小桐子生物柴油运动黏度增大。     

Life cycle energy and greenhouse gas emissions for an ethanol production process based on blue-green algae

Ethanol can be produced via an intracellular photosynthetic process in cyanobacteria (blue-green algae), excreted through the cell walls, collected from closed photobioreactors as a dilute ethanol-in-water solution, and purified to fuel grade ethanol. This sequence forms the basis for a biofuel production process that is currently being examined for its commercial potential. In this paper, we calculate the life cycle energy and greenhouse gas emissions for three different system scenarios for this proposed ethanol production process, using process simulations and thermodynamic calculations. The energy required for ethanol separation increases rapidly for low initial concentrations of ethanol, and, unlike other biofuel systems, there is little waste biomass available to provide process heat and electricity to offset those energy requirements. The ethanol purification process is a major consumer of energy and a significant contributor to the carbon footprint. With a lead scenario based on a natural-gas-fueled combined heat and power system to provide process electricity and extra heat and conservative assumptions around the ethanol separation process, the net life cycle energy consumption, excluding photosynthesis, ranges from 0.55 MJ/MJ(EtOH) down to 0.20 MJ/ MJ(EtOH), and the net life cycle greenhouse gas emissions range from 29.8 g CO?e/MJ(EtOH) down to 12.3 g CO?e/MJ(EtOH) for initial ethanol concentrations from 0.5 wt % to 5 wt %. In comparison to gasoline, these predicted values represent 67% and 87% reductions in the carbon footprint for this ethanol fuel on a energy equivalent basis. Energy consumption and greenhouse gas emissions can be further reduced via employment of higher efficiency heat exchangers in ethanol purification and/ or with use of solar thermal for some of the process heat.     

Use of indirect calorimetry to evaluate utilization of energy in lactating Jersey dairy cattle consuming common coproducts

The use of coproducts as an alternative feed source is a common practice when formulating dairy rations. A study using 12 multiparous (79 ± 16 d in milk; mean ± standard deviation) lactating Jersey cows was conducted over 5 mo to evaluate the effects of dried distillers grains with solubles (DDGS) or canola meal on milk and gas production. A replicated 4 × 4 Latin square design was used to compare 4 dietary treatments. Treatments comprised a control (CON) containing no coproducts, a treatment diet containing 10% (dry matter basis) low-fat DDGS (LFDG), a treatment diet containing 10% high-fat DDGS (HFDG), and a 10% canola meal (CM) treatment. The crude fat content of the LFDG, HFDG, and CM treatments was 6.05 ± 0.379, 10.0 ± 0.134, and 3.46 ± 0.085%, respectively. Coproducts were included in partial replacement for corn and soybean meal. Indirect headbox-style calorimeters were used to estimate heat production. Dry matter intake and milk yield were similar between all treatments, averaging 17.4 ± 0.56 kg/d and 24.0 ± 0.80 kg, respectively. Milk urea N was affected by treatment and was highest in CON (20.6 mg/dL; 18.0, 19.9, and 18.1 ± 0.62 mg/dL in LFDG, CM, and HFDG, respectively). Heat production per unit of metabolic body weight tended to be affected by treatment and was lowest for CON, and diets containing coproducts were not different (192, 200, 215, and 204 ± 5.91 kcal/kg of metabolic body weight for CON, LFDG, CM, and HFDG, respectively). The concentration of metabolizable energy was affected by dietary treatment; specifically, HFDG did not differ from CON but was greater than LFDG and CM (2.58, 2.46, 2.29, and 2.27 ± 0.09 Mcal/kg for HFDG, CON, LFDG, and CM, respectively). The concentration of net energy balance (milk plus tissue) tended to be affected by dietary treatment; HFDG did not differ from either CON or LFDG, but it was higher than CM (1.38, 1.36, 1.14, and 1.06 ± 0.11 Mcal/kg for HFDG, CON, LFDG, and CM, respectively). Results of this study indicate that milk production and dry matter intake were not affected by feeding common coproducts and that differences may result in whole-animal energy use; fat content of DDGS is a major factor affecting this.     

小桐子油生物柴油的热解特性及动力学研究

利用热重分析仪在不同升温速率(10、20、30℃/min)和一定氮气(20 mL/min)条件下对小桐子油生物柴油的热解特性及动力学特性进行了研究。结果表明:小桐子油生物柴油热解过程主要分为低沸点组分挥发,各种脂肪酸甲酯的快速挥发和热解以及残留物缓慢分解失重三个阶段;升温速率增加使各个阶段的起始和终止温度均向高温区轻微移动,使热解失重率略微降低。动力学分析表明:小桐子油生物柴油的热解反应可用三个0.5级反应来描述,根据模型计算的活化能为10.10～85.73 kJ/mol,频率因子为1.82×10-3～1.45×108 min-1。     

麻疯树籽油甲醇解反应体系相图的测绘

为提高反应效率和分离效果,对生物柴油反应体系相行为进行了研究。通过实验分别测定了甲醇-甘油-脂肪酸甲酯和甲醇-脂肪酸甲酯-麻疯树籽油的三元相图。结果表明,脂肪酸甲酯的存在可有效提高麻疯树籽油在甲醇中的溶解度,因此可在一定程度上改善传质效果;甲醇在甲酯相和甘油相之间的分配系数受到温度和甘油含量的显著影响,在低温下可更为彻底地分离甘油副产物,并降低甲醇回收的能耗。     

Heat, electricity, or transportation? The optimal use of residual and waste biomass in Europe from an environmental perspective

The optimal use of forest energy wood, industrial wood residues, waste wood, agricultural residues, animal manure, biowaste, and sewage sludge in 2010 and 2030 was assessed for Europe. An energy system model was developed comprising 13 principal fossil technologies for the production of heat, electricity, and transport and 173 bioenergy conversion routes. The net environmental benefits of substituting fossil energy with bioenergy were calculated for all approximately 1500 combinations based on life cycle assessment (LCA) results. An optimization model determines the best use of biomass for different environmental indicators within the quantified EU-27 context of biomass availability and fossil energy utilization. Key factors determining the optimal use of biomass are the conversion efficiencies of bioenergy technologies and the kind and quantity of fossil energy technologies that can be substituted. Provided that heat can be used efficiently, optimizations for different environmental indicators almost always indicate that woody biomass is best used for combined heat and power generation, if coal, oil, or fuel oil based technologies can be substituted. The benefits of its conversion to SNG or ethanol are significantly lower. For non-woody biomass electricity generation, transportation, and heating yield almost comparable benefits as long as high conversion efficiencies and optimal substitutions are assured. The shares of fossil heat, electricity, and transportation that could be replaced with bioenergy are also provided.     

Economic feasibility evaluation of microfiltration of milk prior to cheesemaking

A nonlinear programming optimization model was used to evaluate the net revenues and potential profit-ability of microfiltration (MF) prior to cheesemaking in the 3-year period 1998 to 2000, using monthly milk price and composition data. The model identifies the optimal mix of milk resources and determines if MF cheesemaking produces a higher net revenue than conventional cheesemaking that uses NDM and condensed milk for fortification. This study demonstrates the potential of this model to evaluate new technologies in cheese manufacture and improve decision making in the cheese industry. The use of MF produced higher net revenues in 30 out of the 36 mo for both Cheddar and low-moisture, part-skim mozzarella, leading to an appreciable increase in net revenue (vs. conventional cheesemaking) for both cheeses. The benefit from MF in net revenue was greater when the cream price was high. The use of 3X MF yielded the same net revenue as 2X MF. An estimate of manufacturing costs of MF vs. conventional cheesemaking was also made. To this end, the yields of products were calculated by the optimization model, while the production cost of each product was estimated from data of two economic engineering studies and a MF cheesemaking trial. The manufacturing cost of MF Cheddar was slightly higher than the manufacturing cost of conventional Cheddar. However, the benefit in net revenue from the use of MF was estimated to be higher than the difference in manufacturing costs. Moreover, some advantages in the new coproducts of MF Cheddar could outweigh its higher manufacturing cost. The relationships between prices and recoveries of coproducts required to render MF profitable were identified.     

小桐子油及其生物柴油多参数的物理特性预测及分析

运用相关物性数据估算方法,得到了小桐子油及其生物柴油的基本物性参数,有效地解决了临界参数难以测定的问题;同时估算出包括气体黏度、液体黏度、表面张力等与传递性质和平衡性质有关的物性参数;分别测定了不同温度下小桐子油及其生物柴油的相关物性,并与估算结果进行对比。结果表明:在实验温度下,小桐子生物柴油运动黏度的最大误差为5. 94%,表面张力的最大误差为5. 70%,估算结果较为准确。     

Localisation of antinutrients and qualitative identification of toxic components in Jatropha curcas seed

BACKGROUND: Jatropha curcas seed oil is a promising feedstock for biodiesel production. The seeds contain major toxic (phorbol esters, PEs) and antinutritional (phytate and trypsin inhibitor) factors. In the present study the localisation of antinutrients and a rapid qualitative method for detecting the presence of PEs were investigated. RESULTS: Kernels were separated into cotyledon, hypocotyl, kernel coat and endosperm. The majority of phytate (96.5%), trypsin inhibitor (95.3%) and PEs (85.7%) were localised in the endosperm. Based on PEs, a qualitative method was developed to differentiate between toxic and non‐toxic Jatropha genotypes. In this method, PEs were easily detected by passing methanol extracts of kernels (Jatropha toxic and non‐toxic genotypes) through a solid phase extraction (SPE) column and measuring the absorption of the resulting eluates at 280 nm. For raw kernels, SPE eluates with absorbance ≥ 0.056 were considered as toxic and those with absorbance ?0.032 as non‐toxic. For defatted kernel meals, SPE eluates with absorbance ≥ 0.059 were considered as toxic and those with absorbance ?0.043 as non‐toxic. CONCLUSION: The majority of antinutrients/toxic compounds are localised in the endosperm of the kernel. The qualitative method developed for rapid identification of toxic PEs could be useful in screening the toxicity of Jatropha‐based products in the biodiesel industry. Further confirmation of PEs should be established by high‐performance liquid chromatography. Copyright © 2011 Society of Chemical Industry     

3种生物柴油成品品质及性能评价

对小桐籽油、棉籽油和橡胶籽油制备出的3种生物柴油进行了一系列的分析检测,并对其品质进行了比较和评价.检测结果表明,3种油制得的纯生物柴油除了氧化安定性以外均可达到国家标准,在添加了适量抗氧剂后氧化安定性也可达到国家标准.将上述3种生物柴油与市售0~#柴油按5%、10%、20%的调合比例掺混,调配成B5、B10、B20的调合生物柴油,并对其进行了全项分析检测,在检测过程中发现0#柴油氧化安定性的检测方法并不适用于所有调合生物柴油.