Applying life-cycle assessment to low carbon fuel standards—How allocation choices influence carbon intensity for renewable transportation fuels

The Energy Independence and Security Act (EISA) of 2007 requires life-cycle assessment (LCA) for quantifying greenhouse gas emissions (GHGs) from expanded U.S. biofuel production. To qualify under the Renewable Fuel Standard, cellulosic ethanol and new corn ethanol must demonstrate 60% and 20% lower emissions than petroleum fuels, respectively. A combined corn-grain and corn-stover ethanol system could potentially satisfy a major portion of renewable fuel production goals. This work examines multiple LCA allocation procedures for a hypothetical system producing ethanol from both corn grain and corn stover. Allocation choice is known to strongly influence GHG emission results for corn-ethanol. Stover-derived ethanol production further complicates allocation practices because additional products result from the same corn production system. This study measures the carbon intensity of ethanol fuels against EISA limits using multiple allocation approaches. Allocation decisions are shown to be paramount. Under varying approaches, carbon intensity for corn ethanol was 36–79% that of gasoline, while carbon intensity for stover-derived ethanol was −10% to 44% that of gasoline. Producing corn-stover ethanol dramatically reduced carbon intensity for corn-grain ethanol, because substantially more ethanol is produced with only minor increases in emissions. Regulatory considerations for applying LCA are discussed.     

Antimicrobial strategies for limiting bacterial contaminants in fuel bioethanol fermentations

Bioethanol continues to be offered as a viable solution for complex problems ranging from global warming and national energy security to local economic development. Fuel bioethanol burns cleaner than gasoline, is derived from renewable agricultural products, and creates local jobs and income. In December 2007, President Bush signed into law the Energy Independence and Security Act, which increased the renewable fuel standard that was mandated under energy Policy Act of 2005 to 36 billion gallons by 2022.In order to achieve this goal, ethanol production would need to be generated primarily from corn and cellulosic materials. Bioethanol producers are currently involved in variety of technological innovations to reduce energy consumption and production costs, increased efficiency and reduced emissions using the best available control technologies. However, industrial ethanol fermentation is a non-sterile process and contaminant microorganisms can lead to a decrease in industrial productivity and significant economic loss. Currently, bioethanol industries use different antimicrobials including antibiotics to control the contaminants in the fermentors. The emergence of antibiotic resistance among contaminant bacteria in bioethanol fermentors warrants the need for alternative antimicrobials to retain bioethanol production at a profitable level. In addition more and more ethanol producers are seeking to generate distillers grains that can be labeled antibiotic free to be sold in international markets where some restrictions are already in place for reducing and/or eliminating antibiotics usage in animal feed. This review examines the contamination problems, various intervention methods, emergence of antibiotic resistance in contaminant bacteria, and potential alternative options to elucidate antimicrobial products from various natural sources. In particular, emphasis has been given for natural antibacterial products from plant derived products to suggest a new research avenue for the search of new, non-conventional antimicrobial agents to control the contamination problem in the fuel bioethanol industries.     

Environmental aspects of ethanol-based fuels from Brassica carinata: A case study of second generation ethanol

One of the main challenges faced by mankind in the 21st century is to meet the increasing demand for energy requirements by means of a more sustainable energy supply. In countries that are net fossil fuel importers, expectation about the benefit of using alternative fuels on reducing oil imports is the primary driving force behind efforts to promote its production and use. Spain is scarce in domestic energy sources and more than 50% of the energy used is fossil fuel based. The promotion of renewable energies use is one of the principal vectors in the Spanish energy policy. Selected herbaceous crops such as Brassica carinata are currently under study as potential energy sources. Its biomass can be considered as potential feedstock to ethanol conversion by an enzymatic process due to the characteristics of its composition, rich in cellulose and hemicellulose. This paper aims to analyse the environmental performance of two ethanol-based fuel applications (E10 and E85) in a passenger car (E10 fuel: a mixture of 10% ethanol and 90% gasoline by volume; E85 fuel: a mixture of 85% ethanol and 15% gasoline by volume) as well as their comparison with conventional gasoline as transport fuel. Two types of functional units are applied in this study: ethanol production oriented and travelling distance oriented functional units in order to reflect the availability or not of ethanol supply. E85 seems to be the best alternative when ethanol production based functional unit is considered in terms of greenhouse gas (GHG) emissions and E10 in terms of non-renewable energy resources use. Nevertheless, E85 offers the best environmental performance when travelling distance oriented functional unit is assumed in both impacts. In both functional unit perspectives, the use of ethanol-based fuels reduces the global warming and fossil fuels consumption. However, the contributions to other impact indicators (e.g. acidification, eutrophication and photochemical oxidants formation) were lower for conventional gasoline.Life Cycle Assessment (LCA) procedure helps to identify the key areas in the B. carinata ethanol production life cycle where the researchers and technicians need to work to improve the environmental performance. Technological development could help in lowering both the environmental impact and the prices of the ethanol fuels.     

Blending under uncertainty: Real options analysis of ethanol plants and biofuels mandates

The value of a representative ethanol producer, that benefits from both low and high gasoline prices in the short-run, is modeled. Ethanol producers make a modest competitive profit in the mandate-induced region of production. A low price of gasoline increases the demand for blend ethanol and consequently increases the profit of ethanol producers. On the other hand, when gasoline becomes costlier than ethanol, the capacity constraints of the biofuels sector bind and ethanol producers gain large quasi-monopoly margins. This is an interesting example of a market where two commodities are complement up to a point and then substitute after that. We postulate the value of an ethanol producer as a strangle option consisting of two real options: the option to substitute gasoline at times of expensive crude oil and the option to expand supply of blend at times of cheap gasoline. Using a dynamic model we show that the higher volatilities of crude oil and ethanol costs increase biofuels firms' value. We also find non-monotonic relationships between the value of an ethanol plant and several underlying variables, including gasoline price level. We estimate the value provided by a 10% blend mandate to be around $150,000,000 for a representative ethanol unit. Our results offer a novel view of oil and feedstock price risks in contrast to the common belief that considers those risks as a negative factor for the biofuels sector.     

Fuel ethanol production from sugarcane and corn: Comparative analysis for a Colombian case

The Colombian government has defined the use of bioethanol as a gasoline enhancer to reduce greenhouse gases, gasoline imports, and to boost the rural economy. To meet the projected fuel ethanol demand needed to oxygenate the gasoline in the whole country, the construction of about five additional ethanol production plants is required. For this, a comparative analysis of the technological options using different feedstocks should be performed. In this work, a comparison of the economical and environmental performance of the ethanol production process from sugarcane and corn under Colombian conditions has been carried out. Net present value and total output rate of potential environmental impact were used as the economical and environmental indicators, respectively. Through the integration of these indicators into one index by using the analytical hierarchy process (AHP) approach, sugarcane ethanol process was determined as the best choice for Colombian ethanol production facilities. AHP scores obtained in this study for sugarcane and corn ethanol were 0.571 and 0.429, respectively. However, starchy crops like corn, cassava or potatoes used as feedstock for ethanol production could potentially cause a higher impact on the rural communities and boost their economies if social matters are considered.     

Solving corrosion problems in biofuels industry

Abstract

Ethanol is increasingly popular as fuel. It is renewable, cleaner than gasoline, and during the 2008 oil price peak, its costs of production without subsidies actually rivalled those of gasoline. The fuel grade ethanol producers are large consumers of stainless steel, in particular for cookers, fermentation tanks, and distillation columns as well as storage tanks for the finished product. The main reason is that cleanliness is important for the enzymes. However, contaminants play an important role in production as well as storage and distribution. Contaminants are causing a phenomenon called stress corrosion cracking. Biodiesel fuel is a mixture of fatty acid alcohol esters. Modern diesel engines are very sensitive to fuel quality and purity. Biodiesel is unstable, just like butter, which is going rancid in a matter of weeks. Biodiesel degradation is an oxidation process, which among others is speeded up by tiny amounts of metal ions leaching from production and storage vessels. Biodiesel vessels need to be designed in non-degradable materials of construction, as stainless steel. In addition, pretreatment of low cost feedstock and methyl recycling operations use strong acids, which also necessitate stainless steels. Biomass is gaining importance as a source for renewable fuels and hydrogen in addition to heat and electricity. Corrosion issues are numerous and include high temperature corrosion under ash and alkali salt deposits and metal dusting at gasification. Fuel grade ethanol, biodiesel and biomass represent three different corrosion issues, which can be solved using the correct stainless steel.     

Are biofuels a feasible option?

Recently a number of objections have been raised against the use of ethanol produced from agricultural products such as maize, sugarcane, wheat or sugar beets as a replacement for gasoline, despite some of their advantages such as being cleaner and to some extent renewable. We address these objections in this paper. Topics discussed include the “corn connection” (which was theorized to be a cause of deforestation in the Amazonia), the rise of food prices due to ethanol production and the real possibilities of ethanol in reducing greenhouse gas emissions. It has been shown that such concerns are grossly exaggerated and that ethanol from sugarcane, as produced in Brazil, is the preferred option for the production of fuel not only in terms of cost but also as a favourable energy balance. Finally, the possibility of expanding ethanol production to other sugar-producing countries is also discussed.     

Economic and policy implications of public support for ethanol production in California's San Joaquin Valley

The US Environmental Protection Agency requires that only oxygenated gasoline may be sold in regions that are not in compliance with national air quality standards. Several non-attainment regions are located in California, and most of the gasoline sold there is oxygenated with methyl tertiary butyl ether (MTBE). California is planning to discontinue the use of MTBE in gasoline by January 2004. This policy will generate greater demand for ethanol, which is the leading substitute for MTBE. Most of the ethanol required in California will be imported from other states, unless California develops an ethanol production industry. The costs of producing ethanol in California may exceed the benefits, unless substantial value is attributed to non-market, public goods, such as maintaining agriculture and reducing unemployment in rural areas. We examine the firm-level economics of using corn and other agricultural products to produce ethanol in California, and the potential regional economic impacts of building and operating an ethanol plant. The cost of production is greater than the current price of ethanol for all of the feedstocks we consider. Production generates economic activity, but at current prices for inputs and outputs, substantial subsidies will be required to encourage firms to produce ethanol in California.     

Life cycle assessment of flax shives derived second generation ethanol fueled automobiles in Spain

Biofuel use seems to have certain environmental, energy and socioeconomic advantages versus fossil fuel consumption. The substitution of fossil fuels with biofuels can be a useful tool to fulfil the Spanish and European policy in relation to mitigation of greenhouse gas (GHG) emissions and increase the security in energy supply. The continuous increase in energy consumption, dependence on energy and high petroleum prices has motivated increasing support for renewable energy promotion. In Spain (the third ethanol producer in Europe in 2007), ethanol from lignocellulosic feedstocks could be one of the most valuable and interesting possibilities for renewable transportation fuels due to the limited competition with food production and high net reduction of GHG emissions. This study is focused on flax shives, obtained as an agricultural co-product from flax crops dedicated to fibre production for specialty paper pulp manufacture as lignocellulosic biomass to produce second generation ethanol involving the use of cellulosic technology. The life cycle assessment (LCA) methodology was used to evaluate the environmental impacts of the production and use in a flexi fuel vehicle (FFV) of ethanol blends (10 and 85% in volume of ethanol with gasoline) versus conventional gasoline, throughout their whole life cycle in order to highlight the main sources of these impacts. The system boundaries include cultivation, extraction, processing and final use of fuels. Mass and economic allocation were considered to determine the effect on the results of different allocation approaches.The results of the study show that the allocation methods are essential for outcomes and decision-making. Using ethanol as transportation fuel could present better environmental performance than conventional gasoline in terms of global warming and fossil fuel consumption according to mass allocation. However, environmental credits could be achieved in terms of acidification, fossil fuel consumption and human toxicity according to economic allocation. Contributions to other impact categories such as eutrophication and photochemical oxidants formation were lower for conventional gasoline regardless of the allocation procedure selected. Agricultural activities related to feedstock production are notable contributors to the environmental performance. Thus, high yielding varieties, reduction of tillage activities and reduction in fertilization should help to reduce these impacts.     

加快煤基醇醚燃料的推广应用——关于建立我国区域醇醚燃料推广应用示范区的建议

我国车用燃料甲醇国家标准和车用甲醇汽油（M85）国家标准已获批准。我国生产甲醇的主要原料是煤,2008年国内煤制甲醇的产能约1270×104t,约占甲醇总产能的61%,预计到2010年,国内将有超过70%的甲醇产能以煤为原料。为加快醇醚燃料进入市场的步伐,建议在我国相关区域建立醇醚燃料产业推广应用示范区,逐步形成规范的区域大市场,在保障我国能源安全、促进能源燃料需求与供给的平衡等方面发挥作用。建立示范区应选择具有一定醇醚燃料生产基础的省份及地区,选择煤炭资源丰富及甲醇工业发展较快的地区和燃料乙醇等生物质能源没有覆盖的地区。并应以大型甲醇或醇醚燃料生产企业为主,以新能源汽车大型生产企业为依托选择示范区。同时,推广醇醚燃料还需要国家政策的支持和各地区、各企业之间的合作,特别是质量认证、市场准入、技术创新、物流运输、醇醚燃料标准化建设等工作,是建立示范区过程中的工作重点。     

Biomass availability for lignocellulosic ethanol production

The ethanol industry in North America uses starch derived from corn as its primary feedstock. In order to better understand the geographical distribution of advanced ethanol production, potential sources of lignocellulosic biomass for the process are considered. It is shown that the corn-producing regions of North America already support significant amounts of ethanol production, and that few unexploited sources of corn remain for the industry to utilize. Accessing other sources of sugar, including other types of biomass such as lignocellulosic materials, will become necessary for the industry as it expands, quite apart from the need to meet government mandates. The ability of bioconversion and thermochemical conversion to generate biofuels from lignocellulosic biomass is reviewed. The availability of lignocellulosic residues from agricultural and forestry operations is described, and the potential biofuel production associated with these residues is described. A residue-based process could greatly extend the potential of the ethanol industry to become a substantial contributor to the fuel and energy requirements of North America. It is estimated that ethanol production from residues could provide up to 13.7% of Canada’s 2009 transportation fuel demand, and up to 5.2% of the United States’ 2010 fuel demand. Utilizing lignocellulosic biomass will extend the geographic range of the biofuel industry, and increase the stability and security of this sector by reducing the impact of localized disruptions in supply. Development of a residue-based industry will help create the technologies needed to process energy crops as North America moves towards greater transportation fuel independence.     

Grain and cellulosic ethanol: History,economics, and energy policy

The United States (US) and Brazil have been the two leading producers of fuel ethanol since the 1970s. National policies have supported the production and use of ethanol from corn and sugarcane. US support in particular has included exemption from federal gasoline excise taxes, whole or partial exemption from road use (sales) taxes in nine states, a federal production tax credit, and a federal blender's credit. In the last decade the subsidization of grain-based ethanol has been increasingly criticized as economically inefficient and of questionable social benefit. In addition, much greater production of ethanol from corn may conflict with food production needs. A promising development is the acceleration of the technical readiness of cellulosic alcohol fuels, which can be produced from the woody parts of trees and plants, perennial grasses, or residues. This technology is now being commercialized and has greater long-term potential than grain ethanol. Cellulosic ethanol is projected to be much more cost-effective, environmentally beneficial, and have a greater energy output to input ratio than grain ethanol. The technology is being developed in North America, Brazil, Japan and Europe. In this paper, we will review the historical evolution of US federal and state energy policy support for and the currently attractive economics of the production and use of ethanol from biomass. The various energy and economic policies will be reviewed and assessed for their potential effects on cellulosic ethanol development relative to gasoline in the US.     

The market and consumer welfare effects of mid-level ethanol blends in the US fuel market

This study examines the prospect that a consumer-driven market could eventually replace the myriad regulations and demand quotas in the US ethanol and gasoline fuel market. Given efficient households that minimize the cost of operating automobiles, recent vehicle technology that improves blended fuel substitution, and typical market conditions of the last five years, blended fuels with 20% ethanol concentration could occupy a volume of 82.2 billion gallons in a 138.3 billion gallon gasoline market. The consumer welfare gain associated with blended fuel is $15.9 billion annually for US consumers, or about $1000 over the life of a vehicle.The ethanol demand associated with a voluntary blended fuel market is 16.4 BGY, slightly more than the conventional component of the Renewable Fuels Standard. It is time to replace the corn RFS with a free market. But an active competition policy in the fuel marketing system may also be required. Intervention for the impending Biomass Ethanol Industry, such as a subsidy or an exemption a carbon tax, may also be in order.     

How does increased corn-ethanol production affect US natural gas prices?

In recent years, there has been a push to increase biofuel production in the United States. The biofuel of choice, so far, has been ethanol produced from corn. The effects of increased corn-ethanol production on the consumer prices of food and energy continue to be studied and debated. This study examines, in particular, the effects of increased corn-ethanol production on US natural gas prices. A structural model of the natural gas market is developed and estimated using two stage least squares. A baseline projection for the period 2007–2018 is determined, and two scenarios are simulated. In the first scenario, current biofuel policies including EISA mandates, tariffs, and tax credits are removed. In the second scenario, we hold ethanol production to the level required only for largely obligatory additive use. The results indicate that the increased level of corn-ethanol production occurring as a result of the current US biofuel policies may lead to natural gas prices that are as much as 0.25% higher, on average, than if no biofuel policies were in place. A similar comparison between the baseline and second scenario indicates natural gas prices could be as much as 0.5% higher, on average, for the same period.     

Assessing the impact of US ethanol on fossil fuel markets: A structural VAR approach

Despite the growing importance of biofuels, the effect of biofuels on fossil fuel markets is not fully understood. We develop a joint structural Vector Auto Regression (VAR) model of the global crude oil, US gasoline, and US ethanol markets to examine whether the US ethanol market has had any impact on global oil markets. The structural VAR approach provides a unique method for decomposing price and quantity data into demand and supply shocks, allowing us to estimate the distinct dynamic effects of ethanol demand and supply shocks on the real prices of crude oil and US gasoline. Ethanol demand in the US is driven mainly by government support in the form of tax credits and blending mandates. Shocks to ethanol demand therefore reflect changes in policy more than any other factor. In contrast, ethanol supply shocks are driven by changes in feedstock prices. A principle finding is that a policy-driven ethanol demand expansion causes a statistically significant decline in real crude oil prices, while an ethanol supply expansion does not have a statistically significant impact on real oil prices. This suggests that even though US ethanol market is small, the influence of US biofuels policy on the crude oil market is pervasive. We also show that ethanol demand shocks are more important than ethanol supply shocks in explaining the fluctuation of real prices of crude oil and US gasoline.     

我国推广使用变性燃料乙醇的环境影响评价

为了解决环境问题和确保国家能源安全,世界各国都在研发可替代能源和清洁能源。变性燃料乙醇是重要的可再生能源之一,目前我国正在试点使用含10%乙醇的乙醇汽油,推广使用乙醇汽油可以综合缓解我国石油短缺、环境恶化和粮食过剩三大热点问题。本文结合国际开展政策性战略环境影响评价的思路和方法,分析推广使用变性燃料乙醇后对环境所产生的影响,得出推广使用变性燃料乙醇具有明显的经济效益、社会效益和环境效益,有利影响远远大于不利影响的结论。最后本文提出推广使用变性燃料乙醇的措施,为在我国顺利推广乙醇汽油提供决策支持。     

Economic feasibility of algal biodiesel under alternative public policies

The motivation for this research was to determine the influence of public policies on economic feasibility of producing algal biodiesel in a system that produced all its energy needs internally. To achieve this, a steady-state mass balance/unit operation system was modeled first. Open raceway technology was assumed for the production of algal feedstock, and the residual biomass after oil extraction was assumed fermented to produce ethanol for the transesterification process. The project assumed the production of 50 million gallons of biodiesel per year and using about 14% of the diesel output to supplement internal energy requirements. It sold the remainder biodiesel and ethanol as pure biofuels to maximize the rents from the renewable fuel standards quota system. Assuming a peak daily yield of 500 kg algal biomass (dry basis)/ha, the results show that production of algal biodiesel under the foregoing constraints is only economically feasible with direct and indirect public policy intervention. For example, the renewable fuel standards' tracking RIN (Renewable fuel Identification Number) system provides a treasury-neutral value for biofuel producers as does the reinstatement of the renewable fuel tax credit. Additionally, the capital costs of an integrated system are such that some form of capital cost grant from the government would support the economic feasibility of the algal biodiesel production.     

The effects of ethanol–unleaded gasoline blends on engine performance and exhaust emissions in a spark-ignition engine

Alcohols have been used as a fuel for engines since 19th century. Among the various alcohols, ethanol is known as the most suited renewable, bio-based and ecofriendly fuel for spark-ignition (SI) engines. The most attractive properties of ethanol as an SI engine fuel are that it can be produced from renewable energy sources such as sugar, cane, cassava, many types of waste biomass materials, corn and barley. In addition, ethanol has higher evaporation heat, octane number and flammability temperature therefore it has positive influence on engine performance and reduces exhaust emissions. In this study, the effects of unleaded gasoline (E0) and unleaded gasoline–ethanol blends (E50 and E85) on engine performance and pollutant emissions were investigated experimentally in a single cylinder four-stroke spark-ignition engine at two compression ratios (10:1 and 11:1). The engine speed was changed from 1500 to 5000 rpm at wide open throttle (WOT). The results of the engine test showed that ethanol addition to unleaded gasoline increase the engine torque, power and fuel consumption and reduce carbon monoxide (CO), nitrogen oxides (NO_x) and hydrocarbon (HC) emissions. It was also found that ethanol–gasoline blends allow increasing compression ratio (CR) without knock occurrence.     

我国燃料乙醇原料可持续供应初步分析

本文通过评价我国粮食供应形势、土地资源、农业生产的特点,资源禀赋等,对我国燃料乙醇原料供应进行了初步分析。我国人多地少,耕地资源紧缺,粮食供需处于紧平衡,以玉米为原料的燃料乙醇发展空间受到极大的限制,原料多元化势在必行。初步测算,2010年燃料乙醇的可供应量约360万t,2020年燃料乙醇的可供应量约1700万t,可以满足国家可再生能源中长期发展规划规定的目标。最后,提出依靠科技进步以及发展纤维素乙醇等措施。     

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.