Ethanol Production Technology Research Articles

Cellulosic biomass could help meet California's transportation fuel needs

Cellulosic biomass, which includes agricultural and forestry residues and woody and herbaceous plants, is the only low-cost resource that can support the sustainable production of liquid fuels on a large enough scale to significantly address our transportation energy needs. The biological conversion of cellulosic biomass to ethanol could offer high yields at low costs, but only if we can improve the technology for releasing simple sugars from recalcitrant biomass. We review key aspects of cellulosic ethanol production, including pretreatment and enzymatic hydrolysis technologies that present the greatest opportunities to lower processing costs. Although several companies seek to introduce cellulosic ethanol commercially, innovative measures are needed to help overcome the perceived risks of first applications.

Enzyme-based hydrolysis processes for ethanol from lignocellulosic materials: A review

This article reviews developments in the technology for ethanol production from lignocellulosic materials by “enzymatic” processes. Several methods of pretreatment of lignocelluloses are discussed, where the crystalline structure of lignocelluloses is opened up, making them more accessible to the cellulase enzymes. The characteristics of these enzymes and important factors in enzymatic hydrolysis of the cellulose and hemicellulose to cellobiose, glucose, and other sugars are discussed. Different strategies are then described for enzymatic hydrolysis and fermentation, including separate enzymatic hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), non-isothermal simultaneous saccharification and fermentation (NSSF), simultaneous saccharification and co-fermentation (SSCF), and consolidated bioprocessing (CBP). Furthermore, the by-products in ethanol from lignocellulosic materials, wastewater treatment, commercial status, and energy production and integration are reviewed.

Simulation of pressure swing adsorption in fuel ethanol production process

Fermentation derived ethanol is gaining wide popularity as a car fuel additive. A major challenge in the production of ethanol is the high energy cost associated with the separation of ethanol from the large excess of water. Distillation is usually the method of choice; however, water cannot be completely removed due to the presence of the azeotrope. The pressure swing adsorption (PSA) process is attractive for the final separation since it requires little energy input and is capable of producing a very pure product. The goal of this work was to perform a thorough analysis of the PSA process and find process improvements with the aid of mathematical modeling. A general purpose package for the simulation of a cyclic PSA process was developed. The system of partial differential equations was solved via method of lines using a stiff equation integration package. Parameters for the model are based on the data from an operating plant as well as data from the literature. For the ethanol production technology our model provides a fundamental understanding of the dynamics of the cyclic process and effects of some operating parameters.

Membrane Dehydration Technology for Commercial Bio Ethanol Production for Fuel

Membrane Dehydration Technology for Commercial Bio Ethanol Production for Fuel

Biorefineries–Industrial Processes and Products: Status Quo and Future Directions

Biorefineries–Industrial Processes and Products: Status Quo and Future Directions

Use of on-farm produced biofuels on organic farms – Evaluation of energy balances and environmental loads for three possible fuels

The aim of this work was to evaluate systems making organic farms self-sufficient in farm-produced bio-based fuels. The energy balance and environmental load for systems based on rape methyl ester (RME), ethanol and biogas were evaluated using a life cycle perspective. Complete LCAs were not performed. Important constraints when implementing the systems in practice were also identified. The RME scenario showed favourable energy balance and produced valuable by-products but was less positive in some other aspects. The use of land was high and thereby also the emissions associated with cultivation. Emissions, with the exception of CO 2, during utilisation of the fuel were high compared to those of the other fuels in the study. The technology for production and use of RME is well known and easy to implement at farm scale. The production of ethanol was energy consuming and the by-products were relatively low value. However, the area needed for cultivation of raw material was low compared to the RME scenario. The production and utilisation of ignition improver and denaturants were associated with considerable emissions. Suitable ethanol production technology is available but is more optimal for large scale systems. The biogas scenario had a low relative need for arable land, which also resulted in smaller soil emissions to air and water. Another advantage was the potential to recycle plant nutrients. On the other hand, the potential emissions of methane from storage of digestate, upgrading of biogas and methane losses during utilisation of fuel produced a negative impact, mainly on global warming. Small scale technology for biogas cleaning and storage is not fully developed and extensive tractor modifications are necessary. The global warming effects of all three systems studied were reduced by 58–72% in comparison to a similar farming system based on diesel fuel. However, the fuel costs were higher for all scenarios studied compared to current diesel prices. In particular, the large costs for seasonal storage of gas meant that the biogas scenario described is currently not financially viable.

Considerations on the worldwide use of bioethanol as a contribution for sustainability

The use of ethanol from biomass as a gasoline substitute in cars and light trucks is possibly one of the most attractive and feasible alternatives to deal with global warming. As environmental concern grows, many countries are increasing their efforts to consolidate bioethanol processes and supply. The sustainable production of bioethanol requires well planned and reasoned development programs to assure that the many environmental, social and economic concerns related to its use are addressed adequately. The key for making ethanol competitive as an alternative fuel is the ability to produce it from low‐cost biomass. Many countries around the world are working extensively to develop new technologies for ethanol production from biomass, from which the lignocellulosic materials conversion seem to be the most promising one. This paper aims at providing some information about the status of bioethanol production and use around the world.

A review of the production of ethanol from softwood.

Ethanol produced from various lignocellulosic materials such as wood, agricultural and forest residues has the potential to be a valuable substitute for, or complement to, gasoline. One of the major resources in the Northern hemisphere is softwood. This paper reviews the current status of the technology for ethanol production from softwood, with focus on hemicellulose and cellulose hydrolysis, which is the major problem in the overall process. Other issues of importance, e.g. overall process configurations and process economics are also considered.

Allocation procedure in ethanol production system from corn grain i. system expansion

We investigated the system expansion approach to net energy analysis for ethanol production from domestic corn grain. Production systems included in this study are ethanol production from corn dry milling and corn wet milling, corn grain production (the agricultural system), soybean products from soybean milling (i.e. soybean oil and soybean meal) and urea production to determine the net energy associated with ethanol derived from corn grain. These five product systems are mutually interdependent. That is, all these systems generate products which compete with or displace all other comparable products in the market place. The displacement ratios between products compare the equivalence of their marketplace functions. The net energy, including transportation to consumers, is 0.56 MJnet/MJ of ethanol from corn grain regardless of the ethanol production technology employed. Using ethanol as a liquid transportation fuel could reduce domestic use of fossil fuels, particularly petroleum. Sensitivity analyses show that the choice of allocation procedures has the greatest impact on fuel ethanol net energy. Process energy associated with wet milling, dry milling and the corn agricultural process also significantly influences the net energy due to the wide ranges of available process energy values. The system expansion approach can completely eliminate allocation procedures in the foreground system of ethanol production from corn grain.

Effect of Alternative Milling Techniques on the Yield and Composition of Corn Germ Oil and Corn Fiber Oil

ABSTRACTThe effects of alternative corn wet‐milling (intermittent milling and dynamic steeping (IMDS), gaseous SO2 and alkali wet‐milling) and dry grind ethanol (quick germ and quick fiber with chemicals) production technologies were evaluated on the yield and phytosterol composition (ferulate phytosterol esters, free phytosterols, and fatty acyl phytosterol esters) of corn germ and fiber oil and compared with the conventional wet‐milling process. Small but statistically significant effects were observed on the yield and composition of corn germ and fiber oil with these alternative milling technologies. The results showed that the germ and fiber fractions from two of the alternative wet‐milling technologies (the gaseous SO2 and the IMDS) had, for almost all of the individual phytosterol compounds, either comparable or signficantly higher yields compared with the conventional wet‐milling process. Also, both of the modified dry grind ethanol processes (the quick germ and quick fiber) with chemicals (SO2 and lactic acid) can be used as a new source of corn germ and fiber and can produce oils with high yields of phytosterols. The alkali wet‐milling process showed significantly lower yields of phytosterols compounds in germ but showed significantly higher yield of free phytosterols, fatty acyl phytosterol esters and total phytosterols in the fiber fraction.

Fuel Ethanol Produced from Midwest U.S. Corn: Help or Hindrance to the Vision of Kyoto?

ABSTRACT In this study, we examined the role of corn-feedstock ethanol in reducing greenhouse gas (GHG) emissions, given present and near-future technology and practice for corn farming and ethanol production. We analyzed the full-fuel-cycle GHG effects of corn-based ethanol using updated information on corn operations in the upper Midwest and existing ethanol production technologies. Information was obtained from representatives of the U.S. Department of Agriculture, faculty of midwestern universities with expertise in corn production and animal feed, and acknowledged authorities in the field of ethanol plant engineering, design, and operations. Cases examined included use of E85 (85% ethanol and 15% gasoline by volume) and E10 (10% ethanol and 90% gasoline). Among key findings is that Midwest-produced ethanol outperforms conventional (current) and reformulated (future) gasoline with respect to energy use and GHG emissions (on a mass emission per travel mile basis). The superiority of the energy and GHG results is well outside the range of model "noise." An important facet of this work has been conducting sensitivity analyses. These analyses let us rank the factors in the corn-to-ethanol cycle that are most important for limiting GHG generation. These rankings could help ensure that efforts to reduce that generation are targeted more effectively.

Likely features and costs of mature biomass ethanol technology

Analysis is undertaken motivated by the question: “What are the likely features and cost of a facility producing ethanol from cellulosic biomass at a level of maturity comparable to a refinery?” This question is considered with respect to cost reductions arising from increased scale, lower-cost feedstock, and process improvements in pretreatment and biological conversion, but not other process steps. An “advanced technology” scenario is developed that represents our estimate of the most likely features of mature biomass ethanol technology. A “best-parameter” scenario, intended to be indicative of the potential for R&D-driven cost reductions, is also developed based on the best values for individual process parameters reported in the literature. Both scenarios involve large plants (2.7 million dry t feedstock/yr). Feedstock costs are taken to be $38.60/delivered dry t for the advanced scenario and $34.00/delivered dry t for the best-parameter scenario. Projected selling prices, including operating costs and capital recovery corresponding to a 14.2% return on investment, are 50¢/gal (pure ethanol basis) for the advanced technology case and 34¢/gal for the best-parameter case. These are markedly lower than the 118¢ /gal selling price projected for base-case technology, with the largest share of cost reductions due to improved conversion technology. Key conversion technology improvements include, in order of importance, consolidated bioprocessing, advanced pretreatment, elimination of seed reactors, and faster rates. First-law thermodynamic efficiencies based on the biomass high heating value and production of ethanol and electricity are 61.2% for the advanced case and 69.3% for the best-parameter case, as compared to 50.3% currently. Combining advanced ethanol production technology of the type presented here with advanced gas turbine-based power generation is a promising direction for future analysis and may offer still further cost reductions and efficiency increases.

Large-scale ethanol production from corn and grain sorghum and improving conversion technology

A linear programming model is used to assess the impacts of large-scale ethanol production from corn and grain sorghum on U.S. agriculture. Annual ethanol production of 22.7 and 45.4sx10 9 L, corresponding to approximately 6 and 12%, respectively, of U.S. gasoline consumption is examined. Current conversion technology allows 387 L of ethanol to be obtained from a metric tonne of corn or grain sorghum, and more advanced conversion technology would allow up to 447 L. U.S. agriculture has the capacity to produce both food and large quantities of ethanol. If large-scale ethanol production occurs, the major change in production is the substitution of corn for soybeans in the north central states. With current ethanol production technology, per unit production cost increases for individual crops range from 3 to 12% and from 6 to 30% for annual ethanol production of 22.7 and 45.4×10 9 L, respectively. Advanced ethanol production technology allows crop production costs to be reduced significantly, about 100o million dollars if 45.4×10 9 L of ethanol are produced.