Cellulosic ethanol

Cellulosic ethanol also know by the name Ceetol, is a
biofuel produced from wood, grasses, or the non-edible parts of plants. [ One Hundred Tenth Congress of the United States of America. [http://frwebgate.access.gpo.gov/cgi-bin/getdoc.cgi?dbname=110_cong_bills%26docid=f:h2419enr.txt.pdf "Food, Conservation, and Energy Act of 2008" (H. R. 2419).] ] Failed verification|date=September 2008

It is a type of biofuel produced from lignocellulose, a structural material that comprises much of the mass of plants. Lignocellulose is composed mainly of cellulose, hemicellulose and lignin. Corn stover, switchgrass, miscanthus, woodchips and the byproducts of lawn and tree maintenance are some of the more popular cellulosic materials for ethanol production. Production of ethanol from lignocellulose has the advantage of abundant and diverse raw material compared to sources like corn and cane sugars, but requires a greater amount of processing to make the sugar monomers available to the microorganisms that are typically used to produce ethanol by fermentation.

Switchgrass and Miscanthus are the major biomass materials being studied today, due to high levels of cellulose. Cellulose, however, is contained in nearly every natural, free-growing plant, tree, and bush, in meadows, forests, and fields all over the world without agricultural effort or cost needed to make it grow.

According to U.S. Department of Energy studies [http://www1.eere.energy.gov/biomass/news.html] conducted by the Argonne Laboratories of the University of Chicago, one of the benefits of cellulosic ethanol is that it reduces greenhouse gas emissions (GHG) by 85% over reformulated gasoline. By contrast, starch ethanol (e.g., from corn), which most frequently uses natural gas to provide energy for the process, may not reduce GHG emissions at all depending on how the starch-based feedstock is produced. [cite journal |url=https://www.environmentcalifornia.org:443/newsletter/fall07/clean-cars-cool-fuels|title=Clean cars, cool fuels |accessdate=2007-11-28 |publisher=Environment California |volume=5 |issue=2 |year=2007] A study by Nobel Prize winner Paul Crutzen found ethanol produced from corn, rapeseed (canola), and sugarcane had a "net climate warming" effect when compared to oil. [Crutzen, PJ, Mosier AR, Smith KA, Winiwarter W. "Nitrous oxide release from agro-biofuel production negates global warming reduction by replacing fossil fuels" "Atmospheric Chemistry and Physics". Disucss., 7 11191–11205, (2007)]

History

The first attempt at commercializing a process for ethanol from wood was done in Germany in 1898. It involved the use of dilute acid to hydrolyze the cellulose to glucose, and was able to produce 7.6 liters of ethanol per 100 kg of wood waste (18 gal per ton). The Germans soon developed an industrial process optimized for yields of around 50 gallons per ton of biomass. This process soon found its way to the United States, culminating in two commercial plants operating in the southeast during World War I. These plants used what was called "the American Process" — a one-stage dilute sulfuric acid hydrolysis. Though the yields were half that of the original German process (25 gallons of ethanol per ton versus 50), the throughput of the American process was much higher. A drop in lumber production forced the plants to close shortly after the end of World War I. In the meantime, a small, but steady amount of research on dilute acid hydrolysis continued at the USDA's Forest Products Laboratory. [Saeman JF. "Kinetics of wood saccharification: Hydrolysis of cellulose and decomposition of sugars in dilute acid at high temperature", "Industrial and Engineering Chemistry", 37(1): 43–52 (1945). ] [ Harris EE, Beglinger E, Hajny GJ, and Sherrard EC. "Hydrolysis of Wood: Treatment with Sulfuric Acid in a stationary digester", "Industrial and Engineering Chemistry", 37(1): 12–23 (1945) ] [Conner AH, Lorenz LF. "Kinetic modeling of hardwood prehydrolysis. Part III. Water and dilute acetic acid Prehydrolysis of southern red oak, "Wood and Fiber Science", 18(2): 248–263 (1986).] During World War II, the US again turned to cellulosic ethanol, this time for convertion to butanediol to produce synthetic rubber. The Vulcan Copper and Supply Comapny was contracted to construct and operate a plant to convert sawdust into ethanol. The plant was based on modifications to the original German Scholler process as developed by the Forest Products Laboratory. This plant achieved an ethanol yield of 50 gal/dry ton but was still not profitable and was closed after the war. [Katzen, R. and Schell, d.J., "Lignocellulosic feedstock Biorefinery: History and Plant Development for Biomass Hydrolysis", pp 129-138 in Biorefineries - Industrial processes and Products, Volume 1, Kamm, B., Gruber, P.R., and Kamm, M., eds. Wiley-VCH, Weinheim, 2006.]

United States President Bush, in his State of the Union address delivered January 31, 2006, proposed to expand the use of cellulosic ethanol. In his State of the Union Address on January 23, 2007, President Bush announced a proposed mandate for 35 billion gallons of ethanol by 2017. It is widely recognized that the maximum production of ethanol from corn starch is 15 billion gallons per year, implying a proposed mandate for production of some 20 billion gallons per year of cellulosic ethanol by 2017. Bush's proposed plan includes $2 billion funding (from 2007-2017?) for cellulosic ethanol plants, with an additional $1.6 billion (from 2007-2017?) announced by the USDA on January 27, 2007.

In March 2007, the US government awarded $385 million in grants aimed at jumpstarting ethanol production from nontraditional sources like wood chips, switchgrass and citrus peels. Half of the six projects chosen will use thermo-chemical methods and half will use cellulosic ethanol methods. [cite web
url=http://www.cbsnews.com/stories/2007/03/04/ap/tech/mainD8NLISJ80.shtml
title=Gasification may be key to U.S. Ethanol
date=2007-03-04
accessdate=2007-11-28
author=Dirk Lammers
publisher=CBS News]

The American company Range Fuels announced in July 2007 that it was awarded a construction permit from the state of Georgia to build the first commercial-scale 100-million-gallon-per-year cellulosic ethanol plant in the United States. [cite web
url=http://www.rangefuels.com/Range-Fuels-awarded-permit-to-construct-the-nations-first-commercial-cellulosic-ethanol-plant
title=Range Fuels awarded permit to construct the nation’s first commercial cellulosic ethanol plant
publisher=Range Fuels
accessdate=2007-11-28
date=2007-07-02] Construction began in November, 2007. [cite web
url=http://www.npr.org/templates/story/story.php?storyId=16019184
title=Georgia plant is first for making ethanol from waste
accessdate=2007-11-28
date=2007-11-05
publisher=NPR
author=Kathleen Schalch]

In April 2008, George Huber of the University of Massachusetts Amherst received a $400,000 CAREER grant from the National Science Foundation to pursue his revolutionary new method for making biofuels, or "green gasoline". The U.S. could potentially produce 1.3 billion dry tons of cellulosic biomass per year, which has the energy content of four billion barrels of crude oil. This translates to 65% of American oil consumption.Fact|date=August 2008

Production methods

There are two ways of producing alcohol from cellulose:
* Cellulolysis processes which consist of hydrolysis on pretreated lignocellulosic materials, using enzymes to break complex cellulose into simple sugars such as glucose and followed by fermentation and distillation.
* Gasification that transforms the lignocellulosic raw material into gaseous carbon monoxide and hydrogen. These gases can be converted to ethanol by fermentation or chemical catalysis.

They both include distillation as the final step to isolate the pure ethanol.

Cellulolysis (biological approach)

There are four or five stages to produce ethanol using a biological approach:
# A "pretreatment" phase, to make the lignocellulosic material such as wood or straw amenable to hydrolysis,
# Cellulose hydrolysis (cellulolysis), to break down the molecules into sugars;
# Separation of the sugar solution from the residual materials, notably lignin;
# Microbial fermentation of the sugar solution;
# Distillation to produce 99.5% pure alcohol.

Pretreatment

Although cellulose is the most abundant plant material resource, its susceptibility has been curtailed by its rigid structure. As the result, an effective pretreatment is needed to liberate the cellulose from the lignin seal and its crystalline structure so as to render it accessible for a subsequent hydrolysis step. [ Mosier N, Wyman C, Dale BE, Elander R, Lee YY, Holtzapple M, Ladisch M (2005) Features of promising technologies for pretreatment of lignocellulosic biomass. Bioresour Technol 96:673-686 ] By far, most pretreatments are done through physical or chemical means. In order to achieve higher efficiency, some researchers seek to incorporate both effects. [ McMillan JD (1994) Pretreatment of lignocellulosic biomass. In: Himmel ME, Baker JO, Overend RP, Enzymatic Conversion of Biomass for Fuels Production, ACS Symposium Series, vol. 556. ACS, Washington, DC, 292–324. ]

To date, the available pretreatment techniques include acid hydrolysis, steam explosion, ammonia fiber expansion, alkaline wet oxidation and ozone pretreatment. [ Klinke HB, Thomsen AB, Ahring BK (2004) Inhibition of ethanol-producing yeast and bacteria by degradation products produced during pre-treatment of biomass. Appl Microbiol Biotechnol 66:10–26.] Besides effective cellulose liberation, an ideal pretreatment has to minimize the formation of degradation products because of their inhibitory effects on subsequent hydrolysis and fermentation processes. [ Olsson L, Hahn-Hägerdal B (1996) Fermentation of lignocellulosic hydrolysates for ethanol fermentation. Enzyme Microb Technol 18:312–331. ] The presence of inhibitors will not only further complicate the ethanol production but also increase the cost of production due to entailed detoxification steps. Even though pretreatment by acid hydrolysis is probably the oldest and most studied pretreatment technique, it produces several potent inhibitors including furfural and hydroxymethyl furfural (HMF) which are by far regarded as the most toxic inhibitors present in lignocellulosic hydrolysate. [ Palmqvist E, Hahn-Hägerdal B (2000) Fermentation of lignocellulosic hydrolysates. I. Inhibition and deoxification. Bioresour Technol 74:17–24. ] In fact, Ammonia Fiber Expansion (AFEX) is the sole pretreatment which features promising pretreatment efficiency with no inhibitory effect in resulting hydrolysate. Lynd LR (1996) Overview and evaluation of fuel ethanol from cellulosic biomass: technology, economics, the environment, and policy. Annu Rev Energy Environ 21:403–465. ]

Cellulolytic processes

The cellulose molecules are composed of long chains of sugar molecules. In the hydrolysis process, these chains are broken down to free the sugar, before it is fermented for alcohol production.

There are two major cellulose hydrolysis (cellulolysis) processes: a chemical reaction using acids, or an enzymatic reaction.

Chemical hydrolysis

In the traditional methods developed in the 19th century and at the beginning of the 20th century, hydrolysis is performed by attacking the cellulose with an acid. [ [http://journeytoforever.org/biofuel_library/wood_alcohol.html Wood Alcohol] . Translation from E. Boullanger: Distillerie Agricole et Industrielle (Paris: Ballière, 1924).] Dilute acid may be used under high heat and high pressure, or more concentrated acid can be used at lower temperatures and atmospheric pressure, like BlueFire Ethanol (OTCBB: BFRE). A decrystalized cellulosic mixture of acid and sugars reacts in the presence of water to complete individual sugar molecules (hydrolysis). The product from this hydrolysis is then neutralized and yeast fermentation is used to produce ethanol. As mentioned, a significant obstacle to the dilute acid process is that the hydrolysis is so harsh that toxic degradation products are produced that can interfere with fermentation. Concentrated acid must be separated from the sugar stream for recycle (simulated moving bed (SMB) chromatographic separation for example) to be commercially attractive.

Enzymatic hydrolysis

Cellulose chains can be broken into glucose molecules by cellulase enzymes.

This reaction occurs at body temperature in the stomach of ruminants such as cows and sheep, where the enzymes are produced by bacteria. This process uses several enzymes at various stages of this conversion. Using a similar enzymatic system, lignocellulosic materials can be enzymatically hydrolyzed at a relatively mild condition (50^oC and pH5), thus enabling effective cellulose breakdown without the formation of byproducts that would otherwise inhibit enzyme activity. All major pretreatment methods, including dilute acid pretreatment, require enzymatic hydrolysis step to achieve high sugar yield for ethanol fermentation.Currently, most pretreatment studies have been laboratory based, but companies are rapidly exploring means to transistion from the laboratory to pilot, or production scale. [http://www.biomassmagazine.com/article-print.jsp?article_id=1737 Biomass magazine reference article]

Various enzyme companies have also contributed significant technological breakthroughs in cellulosic ethanol through the mass production of enzymes for hydrolysis at competitive prices.

The fungus Trichoderma reesei is used by Iogen Corporation, to secrete "specially engineered enzymes" for an enzymatic hydrolysis process. [cite web
url=http://www.iogen.ca/cellulose_ethanol/what_is_ethanol/process.html
publisher=Iogen Corp
title=Iogen technology makes it possible (process overview)
year=2005
accessdate=2007-11-28] The raw material (wood or straw) has to be pre-treated to make it amenable to hydrolysis.

Another Canadian company, SunOpta markets a patented technology known as "Steam Explosion" to pre-treat cellulosic biomass, overcoming its "recalcitance" to make cellulose and hemicellulose accessible to enzymes for conversion into fermenatable sugars. SunOpta designs and engineers cellulosic ethanol biorefineries and its process technologies and equipment are in use in the first 3 commercial demonstration plants in the world: [ [http://phx.corporate-ir.net/phoenix.zhtml?c=82712&p=irol-newsArticle&t=Regular&id=951516 "Sunopta updates current cellulosic ethanol projects"] . Sunopta press release, 2007.] Verenium (formerly Celunol Corporation)'s facility in Jennings, Louisiana, Abengoa's facility in Salamanca, Spain, and a facility in China owned by China Resources Alcohol Corporation (CRAC). The CRAC facility is currently producing cellulosic ethanol from local corn stover on a 24-hour a day basis utilizing SunOpta's process and technology.

Genencor and Novozymes are two other companies that have received United States Department of Energy funding for research into reducing the cost of cellulase, a key enzyme in the production of cellulosic ethanol by enzymatic hydrolysis.

Other enzyme companies, such as Dyadic International, [ [http://www.dyadic-group.com/ Dyadic International (AMEX: DIL)] ] are developing genetically engineered fungi which would produce large volumes of cellulase, xylanase and hemicellulase enzymes which can be utilized to convert agricultural residues such as corn stover, distiller grains, wheat straw and sugar cane bagasse and energy crops such as switch grass into fermentable sugars which may be used to produce cellulosic ethanol.

Verenium, formed by the merger of Diversa and Celunol, operates a pilot cellulosic ethanol plant in Jennings, Louisiana and is building a 1.4 million gallon per year demonstration plant on adjacent land to be completed by the end of 2007 and begin operation in early 2008. Verenium is the first publicly traded company with integrated, end-to-end capabilities to make cellulosic biofuels.

Microbial fermentation

Traditionally, baker’s yeast ("Saccharomyces cerevisiae"), has long been used in brewery industry to produce ethanol from hexoses (6-carbon sugar). Due to the complex nature of the carbohydrates present in lignocellulosic biomass, a significant amount of xylose and arabinose (5-carbon sugars derived from the hemicellulose portion of the lignocellulose) is also present in the hydrolysate. For example, in the hydrolysate of corn stover, approximately 30% of the total fermentable sugars is xylose. As a result, the ability of the fermenting microorganisms to utilize the whole range of sugars available from the hydrolysate is vital to increase the economic competitiveness of cellulosic ethanol and potentially bio-based chemicals.

In recent years, metabolic engineering for microorganisms used in fuel ethanol production has shown significant progress. [ Jeffries TW, Jin YS (2004) Metabolic engineering for improved fermentation of pentoses by yeasts. Appl Microbiol Biotechnol 63: 495–509. ] Besides "Saccharomyces cerevisiae", microorganisms such as "Zymomonas mobilis" and "Escherichia coli" have been targeted through metabolic engineering for cellulosic ethanol production.

Recently, engineered yeasts have been described efficiently fermenting xylose [ Ohgren K, Bengtsson O, Gorwa-Grauslund MF, Galbe M, Hahn-Hagerdal B, Zacchi G (2006) Simultaneous saccharification and co-fermentation of glucose and xylose in steam-pretreated corn stover at high fiber content with Saccharomyces cerevisiae TMB3400. J Biotechnol. 126(4):488–98. ] and arabinose, [ Becker J, Boles E (2003) A modified Saccharomyces cerevisiae strain that consumes L-Arabinose and produces ethanol. Appl Environ Microbiol. 69(7):4144–50.] and even both together. [ Karhumaa K, Wiedemann B, Hahn-Hagerdal B, Boles E, Gorwa-Grauslund MF (2006) Co-utilization of L-arabinose and D-xylose by laboratory and industrial Saccharomyces cerevisiae strains. Microb Cell Fact. 10;5:18.] Yeast cells are especially attractive for cellulosic ethanol processes as they have been used in biotechnology for hundred of years, as they are tolerant to high ethanol and inhibitor concentrations and as they can grow at low pH values which avoids bacterial contaminations.

Combined hydrolysis and fermentation

Some species of bacteria have been found capable of direct conversion of a cellulose substrate into ethanol. One example is "Clostridium thermocellum", which utilizes a complex cellulosome to break down cellulose and synthesize ethanol. However, "C. thermocellum" also produces other products during cellulose metabolism, including acetate and lactate, in addition to ethanol, lowering the efficiency of the process. Some research efforts are directed to optimizing ethanol production by genetically engineering bacteria that focus on the ethanol-producing pathway. [ [http://www.rochester.edu/news/show.php?id=2803 University of Rochester Press Release:] Genome Sequencing Reveals Key to Viable Ethanol Production]

Gasification process (thermochemical approach)

The gasification process does not rely on chemical decomposition of the cellulose chain (cellulolysis). Instead of breaking the cellulose into sugar molecules, the carbon in the raw material is converted into synthesis gas, using what amounts to partial combustion. The carbon monoxide, carbon dioxide and hydrogen may then be fed into a special kind of fermenter. Instead of sugar fermentation with yeast, this process uses a microorganism named "Clostridium ljungdahlii". [ cite web |url=http://www.brienergy.com/index.html |title=Providing for a Sustainable Energy Future by producing clean RENEWABLE liquid energy and green power |accessdate=2007-11-28 |publisher=Bioengineering Resources Inc.] This microorganism will ingest (eat) carbon monoxide, carbon dioxide and hydrogen and produce ethanol and water. The process can thus be broken into three steps:
# Gasification — Complex carbon based molecules are broken apart to access the carbon as carbon monoxide, carbon dioxide and hydrogen are produced
# Fermentation — Convert the carbon monoxide, carbon dioxide and hydrogen into ethanol using the "Clostridium ljungdahlii" organism
# Distillation — Ethanol is separated from water

A recent study has found another "Clostridium" bacterium that seems to be twice as efficient in making ethanol from carbon monoxide as the one mentioned above. [ "Formation of Ethanol from Carbon Monoxide via New Microbial Catalyst", "Biomass & Energy" v. 23 (2002), p. 487–493.]

Alternatively, the synthesis gas from gasification may be fed to a catalytic reactor where the synthesis gas is used to produce ethanol and other higher alcohols through a thermochemical process. [ cite web |url=http://www.powerenergy.com/ |title=Power Energy Fuels Homepage |publisher=Power Energy Fuels, Inc. |accessdate=2007-11-28] This process can also generate other types of liquid fuels, an alternative concept under investigation by at least one biofuels company. [cite web |url=http://www.choren.com/en |title=Following Nature's Example |publisher=Chloren Industries |accessdate=2007-11-28]

Economics

After the ethanol is produced, it must be distilled from the mash. Most US producers use natural gas to provide the heat of distillation. In Brazil, producers are known to burn waste sugar cane stalks to distill their ethanol.

Construction of pilot scale lignocellulosic ethanol plants requires considerable financial support through grants and subsidies. On 28 February 2007, the U.S. Dept. of Energy announced $385 million in grant funding to six cellulosic ethanol plants. [cite web |url=http://www.doe.gov/news/4827.htm |title=DOE Selects Six Cellulosic Ethanol Plants for Up to $385 Million in Federal Funding|publisher=United States Department of Energy |date=2007-02-28] This grant funding accounts for 40% of the investment costs. The remaining 60% comes from the promoters of those facilities. Hence, a total of $1 billion will be invested for approximately 140 million gallon capacity. This translates into $7/annual gallon production capacity in capital investment costs for pilot plants (this would work out to $.35/gal over the 20-year life of a facility); future capital costs are expected to be lower. Corn to ethanol plants cost roughly $1–3/annual gallon capacity, though the cost of the corn itself is considerably greater than for switchgrass or waste biomass. [cite web |url=http://www1.eere.energy.gov/biomass/pdfs/37092.pdf |format=PDF |title=Feasibility Study for Co-Locating and Integrating Ethanol Production Plants from Corn Starch and Lignocellulosic Feedstocks |publisher=United States Department of Energy |date=2005-01] [ cite web |url=http://www.ethanol-gec.org/information/briefing/16.pdf |format=PDF |title=Determining the Cost of Producing Ethanol from Corn Starch and Lignocellulosic Feedstocks |publisher=U.S. Department of Agriculture and U.S. Department of Energy|date=2000-10]

The quest for alternative sources of energy has provided many ways to produce electricity, such as wind farms, hydropower, or solar cells. However, about 20% of total energy consumption is dedicated to transportation (i.e., cars, planes, lorries/trucks, etc.) [cite web |url=http://www.eia.doe.gov/aer/pdf/pages/sec2_4.pdf |format=PDF |title=Energy Consumption by Sector, 1949–2006 |publisher=Energy Information Administration |date=2007-01] and currently requires energy-dense liquid fuels such as gasoline, diesel fuel, or kerosene. These fuels are all obtained by refining petroleum. This dependency on oil has two major drawbacks: burning fossil fuels such as oil may contribute to global warming; and for net-consuming countries like the United States, importing oil creates a dependency on oil-producing countries.

As of 2007, ethanol is produced mostly from sugars or starches, obtained from fruits and grains. In contrast, cellulosic ethanol is obtained from cellulose, the main component of wood, straw and much of the structure of plants. Since cellulose cannot be digested by humans, the production of cellulose does not compete with the production of food, other than conversion of land from food production to cellulose production (which has recently started to become an issue, due to rising wheat prices.) The price per ton of the raw material is thus much cheaper than grains or fruits. Moreover, since cellulose is the main component of plants, the whole plant can be harvested. This results in much better yields per acre — up to 10 tons, instead of 4 or 5 tons for the best crops of grain.Fact|date=August 2007

The raw material is plentiful. Cellulose is present in every plant, in the form of straw, grass, and wood. Most of these "bio-mass" products are currently discarded. It is estimated that 323 million tons of cellulose containing raw materialsthat could be used to create ethanol are thrown away each year.This includes36.8 million dry tons of urban wood wastes, 90.5 million dry tons of primary mill residues, 45 million dry tons of forest residues, and 150.7 million dry tons of corn stover & wheat straw.cite web |url=http://bioenergy.ornl.gov/papers/misc/resource_estimates.html |title=Biomass Resource Estimates] Transforming them into ethanol using efficient and cost effective hemi(cellulase) enzymes or other processes might provide as much as 30% of the current fuel consumption in the United States — and probably similar figures in other oil-importing regions like China or Europe.Fact|date=April 2007

Moreover, even land marginal for agriculture could be planted with cellulose-producing crops like switchgrass, resulting in enough production to substitute for all the current oil imports into the United States. [cite web
url= http://www.planetark.com/dailynewsstory.cfm/newsid/46338/story.htm
title= Switchgrass Fuel Yields Bountiful Energy: Study
date= January 10, 2008 | publisher= Reuters
pages= |language= |doi= |archiveurl= |archivedate= |quote=
accessdate= 2008-02-12 ]

Paper, cardboard, and packaging comprise a substantial part of the solid waste sent to landfills in the United States each day, 41.26% of all organic municipal solid waste (MSW) according to [http://www.ciwmb.ca.gov/ California Integrated Waste Management Board] 's city profiles. These city profiles account for accumulation of 612.3 tons daily per landfill where an average population density of 2,413 per square mile persists. Organic waste consists of 0.4% Manures, 1.6% Gypsum Board, 4.2% Glossy Paper, 4.2% Paper Ledger, 9.2% Wood, 10.5% Envelopes, 11.9% Newsprint, 12.3% Grass & Leaves, 30.0% Food Scrap, 34.0% Office Paper, 35.2% Corrugated Cardboard, and 46.4% Agricultural Composites, makes up 71.51% of land fill. All these except Gypsum Board contain cellulose which is transformable into cellulosic ethanol because they are the leading cause of methane plumes. Methane, a greenhouse gas, is 21 times more potent than carbon-dioxide. [ "National Geographic Magazine", 'Carbon's New Math', October 2007]

Reduction of the disposal of solid waste through cellulosic ethanol conversion would reduce solid waste disposal costs by local and state governments. It is estimated that each person in the US throws away convert|4.4|lb|abbr=on of trash each day, of which 37% contains waste paper which is largely cellulose. That computes to 244 thousand tons per day of discarded waste paper that contains cellulose. [ [300 million people × convert|4.4|lb|abbr=on per person × 37% is paper / 2000 lb per ton] ] The raw material to produce cellulosic ethanol is not only free, it has a negative cost — i.e., ethanol producers can get paid to take it away. [ cite web |url=http://www.des.state.nh.us/SWPlan/SWGeneration.pdf |format=PDF |title=Solid Waste Generation]

In June 2006, a U.S. Senate hearing was told that the current cost of producing cellulosic ethanol is US $2.25 per US gallon (US $0.59/litre). This is primarily due to the current poor conversion efficiency.Fact|date=December 2007 At that price it would cost about $120 to substitute a barrel of oil (42 gallons), taking into account the lower energy content of ethanol. However, the Department of Energy is optimistic and has requested a doubling of research funding. The same Senate hearing was told that the research target was to reduce the cost of production to US $1.07 per US gallon (US $0.28/litre) by 2012. "The production of cellulosic ethanol represents not only a step toward true energy diversity for the country, but a very cost-effective alternative to fossil fuels. It is advanced weaponry in the war on oil,” said Vinod Khosla, managing partner of Khosla Ventures, who recently told a Reuters Global Biofuels Summit that he could see cellulosic fuel prices sinking to $1 per gallon within ten years.

University of Massachusetts at Amherst researchers have developed a streamlined technique which uses "catalytic fast pyrolysis" (heating to 400–600 °C followed by rapid cooling) and zeolite as a catalyst to produce cellulosic ethanol in about 60 seconds. They estimate improvements in the process should be able to generate ethanol at the equivalent of $1–$1.70/gal of gasoline. As of April 2008, the process has only been developed to work at laboratory scales. cite web
url= http://www.energy-daily.com/reports/New_Method_Rapidly_Produces_Low_Cost_Biofuels_From_Wood_Grass_999.html
title= New Method Rapidly Produces Low-Cost Biofuels From Wood, Grass
date= 2008-04-14 |work= |publisher= Energy Daily
accessdate= 2008-05-15 ]

Environmental effects: corn-based vs. grass-based

On 2008, there was only a small amount of switchgrass dedicated for ethanol production. In order for it to be grown on a large-scale production it must compete with existing uses of agricultural land, mainly for the production of crop commodities. Of the United States' 2.26 billion acres (9.1 million km²) of unsubmerged land, [The World Fact Book, www.cia.org, 01 May 2008] 33% are forestland, 26% pastureland and grassland, and 20% crop land. A study done by the U.S. Departments of Energy and Agriculture in 2005, determined whether there were enough available land resources to sustain production of over 1 billion dry tons of biomass annually to replace 30% or more of the nation’s current use of liquid transportation fuels. The study found that there could be 1.3 billion dry tons of biomass available for ethanol use, by making little changes in agricultural and forestry practices and meeting the demands for forestry products, food, and fiber.cite web
publisher=U.S. Department of Energy Office of Science
year=2007
title=Cellulosic Ethanol: Benefits and Challenges. Genomics: GTL
url=http://genomicsgtl.energy.gov/biofuels/benefits.shtml
accessdate=2007-12-09] A recent study done by the University of Tennessee reported that as many as 100 million acres (400,000 km², or 154,000 sq. miles), of cropland and pasture will need to be allocated to switchgrass production in order to offset petroleum use by 25 percent.cite web
author=Montenegro M
year=2006
title=The Big Three
publisher=Grist Environmental News
url=http://grist.org/news
accessdate=2007-12-10]

Currently, corn is easier and less expensive to process into ethanol in comparison to cellulosic ethanol. The Department of Energy estimates that it costs about $2.20 per gallon to produce cellulosic ethanol, which is twice as much as ethanol from corn. Enzymes that destroy plant cell wall tissue cost 30 to 50 cents per gallon of ethanol compared to 3 cents per gallon for corn.cite web
author=Weeks, J
year=2006
title=Are We There Yet? Not quite, but cellulosic ethanol may be coming sooner than you think
publisher=Grist Magazine
url=http://www.grist.org/news/maindish/2006/12/11/weeks/index.html
accessdate=2007-12-08] The Department of Energy hopes to reduce this cost to $1.07 per gallon by 2012 to be effective. However, cellulosic biomass is cheaper to produce than corn, because it requires fewer inputs, such as energy, fertilizer, herbicide, and is accompanied by less soil erosion and improved soil fertility. Additionally, nonfermentable and unconverted solids left after making ethanol can be burned to provide the fuel needed to operate the conversion plant and produce electricity. Energy used to run corn-based ethanol plants is derived from coal and natural gas. The Institute for Local Self-Reliance estimates the cost of cellulosic ethanol from the first generation of commercial plants will be in the $1.90–$2.25 per gallon range, excluding incentives. This compares to the current cost of $1.20–$1.50 per gallon for ethanol from corn and the current retail price of over $4.00 per gallon for Regular Gasoline (which is subsidized and taxed).cite web
publisher=ILSR Daily
year=2007
title=Cellulosic ethanol: fuel of the future?
url=http://www.newrules.org/agri/celluloseethanol.pdf]

One of the major reasons for increasing the use of biofuels is to reduce greenhouse gas emissions.cite web
publisher=Science Daily
year=2007
title=Cellulosic ethanol: Fuel of the future?
url=http://www.sciencedaily.com/releases/2007/02/070218140448.htm
accessdate=2007-12-10] In comparison to gasoline, ethanol burns cleaner with a greater efficiency, thus putting less carbon dioxide and overall pollution in the air. Additionally, only low levels of smog are produced from combustion.cite journal
author=Demain A, Newcomb M, Wu D
month=March
year=2005
title= Cellulase, Clostridia, and Ethanol. Microbiology
journal=Molecular Biology Reviews
issue=69
pages=124–154] According to the U.S. Department of Energy, ethanol from cellulose reduces green house gas emission by 90 percent, when compared to gasoline and in comparison to corn-based ethanol which decreases emissions by 10 to 20 percent. Carbon dioxide gas emissions are shown to be 85% lower than those from gasoline. Cellulosic ethanol contributes little to the greenhouse effect and has a five times better net energy balance than corn-based. When used as a fuel, cellulosic ethanol releases less sulfur, carbon monoxide, particulates, and greenhouse gases. Cellulosic ethanol should earn producers carbon reduction credits, higher than those given to producers who grow corn for ethanol, which is about 3 to 20 cents per gallon.

It takes 0.76 J of energy from fossil fuels to produce 1 J worth of ethanol from corn.cite journal
author = Farrell AE, Plevin RJ, Turner BT, Jones AD, O’Hare M, Kammen DM
date=2006-01-27
title = Ethanol can contribute to energy and environmental goals
journal = Science
volume = 311
pages = 506–508
doi = 10.1126/science.1121416
pmid = 16439656] This total includes the use of fossil fuels used for fertilizer, tractor fuel, ethanol plant operation, etc. Research has shown that 1 gallon of fossil fuel can produce over 5 gallons of ethanol from prairie grasses, according to Terry Riley, President of Policy at the Theodore Roosevelt Conservation Partnership. The United States Department of Energy concludes that corn-based ethanol provides 26 percent more energy than it requires for production, while cellulosic ethanol provides 80 percent more energy. Cellulosic ethanol yields 80 percent more energy than is required to grow and convert it.cite journal
author=Ratliff E
year=2007
title=One molecule could cure our addiction to oil
journal=Wired Magazine
issue=10
volume=15] The process of turning corn into ethanol requires about 1,700 gallons of water for every 1 gallon of ethanol produced. Additionally, each gallon of ethanol leaves behind 12 gallons of waste that must be disposed.cite journal
author=Marshall B
month=October
year=2007
title=Gas from the grass
journal=Field and Stream
pages=40–42] Grain ethanol uses only the edible portion of the plant. Expansion of corn acres for the production of ethanol poses threats to biodiversity. Corn lacks a strong root system, therefore, when produced, it causes soil erosion. This has a direct effect on soil particles, along with excess fertilizers and other chemicals, washing into local waterways, damaging water quality and harming aquatic life. Planting riparian areas can serve as a buffer to waterways, and decrease runoff.

Cellulose is not used for food and can be grown in all parts of the world. The entire plant can be used when producing cellulosic ethanol. Switchgrass yields twice as much ethanol per acre than corn. Therefore, less land is needed for production and thus less habitat fragmentation. Biomass materials require fewer inputs, such as fertilizer, herbicides, and other chemicals that can pose risks to wildlife. Their extensive roots improve soil quality, reduce erosion, and increase nutrient capture. Herbaceous energy crops reduce soil erosion by greater than 90%, when compared to conventional commodity crop production. This can translate into improved water quality for rural communities. Additionally, herbaceous energy crops add organic material to depleted soils and can increase soil carbon, which can have a direct effect on climate change.cite web
author=Nelson R
year=2007
title=Cellulosic ethanol: bioethanol in Kansas
url=http://kec.kansas.gov/reports/Cellulosic_Ethanol_FINAL.pdf
format=PDF
accessdate=2007-12-09] As compared to commodity crop production, biomass reduces surface runoff and nitrogen transport. Switchgrass provides an environment for diverse wildlife habitation, mainly insects and ground birds. Conservation Resource Program (CRP) land is composed of perennial grasses, which are used for cellulosic ethanol, and may be available for use.

Feedstocks

Switchgrass is a native prairie grass of "the tall grass prairie", in contrast to the short grass of the "high plains". Known for its hardiness and rapid growth, this perennial grows during the warm months to heights of 2–6 feet. Switchgrass can be grown in most parts of the United States, including swamplands, plains, streams, and along the shores & "interstate highways". It is "self-seeding" (no tractor for sowing, only for mowing), resistant to many diseases and pests, & can produce high yields with low applications of fertilizer and other chemicals. It is also tolerant to poor soils, flooding, & drought; improves soil quality and prevents erosion due its type of root system.cite web |author=Rinehart, L.
year=2006
title=Switchgrass as a Bioenergy Crop. National Sustainable Agriculture Information Service
url=http://attra.ncat.org/attra-pub/PDF/switchgrass.pdf#xml=http://search.ncat.org/texis/search/pdfhi.txt?query=Rinehart&pr=ATTRAv2&prox=page&rorder=500&rprox=500&rdfreq=500&rwfreq=500&rlead=500&rdepth=0&sufs=0&order=r&cq=&id=4770e3036d
accessdate=2007-12-10]

Switchgrass is an approved cover crop for land protected under the federal Conservation Reserve Program (CRP). CRP is a government program that pays producers a fee for not growing crops on land on which crops recently grew. This program reduces soil erosion, enhances water quality, and increases wildlife habitat. CRP land serves as a habitat for upland game, such as pheasants and ducks, and a number of insects. Switchgrass for biofuel production has been considered for use on Conservation Reserve Program (CRP) land, which could increase ecological sustainability and lower the cost of the CRP program. However, CRP rules would have to be modified to allow this economic use of the CRP land.

Miscanthus x giganteus is another viable feedstock for cellulosic ethanol production. This species of grass is native to Asia and is the sterile triploid hybrid of "miscanthus sinensis" and "miscanthus sacchariflorus". It can grow up to convert|12|ft|m tall with little water or fertilizer input. Miscanthus is similar to switchgrass with respect to cold and drought tolerance and water use efficiency. Miscanthus is commercially grown in the European Union as a combustible energy source.

Corn cobs and leaves, wood chips and paper pulp are also feedstocks for cellulosic ethanol [http://www.technologyreview.com/Energy/21347/?nlid=1325] .

Cellulosic ethanol commercialization

Cellulosic ethanol commercialization can contribute to a successful renewable fuels future.

Companies such as Iogen, Broin, and Abengoa are all building refineries that can process biomass and turn it into ethanol, while companies such as Diversa, Novozymes, and Dyadic are producing enzymes and Butalco [ [http://www.butalco.com BUTALCO GmbH] ] is developing improved yeast strains, which could enable a cellulosic ethanol future. The shift from food crop feedstocks to waste residues and native grasses offers significant opportunities for a range of players, from farmers to biotechnology firms, and from project developers to investors. [ Pernick Ron, Wilder Clint (2007). "The Clean Tech Revolution" p. 96.]

A biorefinery built to produce 1.4 million gallons of ethanol a year from cellulosic biomass has opened in Jennings, LA. Built by Verenium, based in Cambridge, MA, the plant makes ethanol from agricultural waste left over from processing sugarcane. [cite web |url=http://www.technologyreview.com/Energy/20828/?nlid=1099 |title=Cellulosic Ethanol Plant Opens |accessdate=2008-09-07 |author=Kevin Bullis |date=May 28, 2008 |work=Technology Review |publisher=]

Gulf Ethanol Corporation

Gulf Ethanol Corporation [ [http://www.GulfEthanolCorp.com Gulf Ethanol Corporation (GFET)] ] announced in June 2008 that it has established an R&D facility dedicated to refining the design of its cellulosic feedstock preprocessor. Cellulosic feedstock is used to produce ethanol from non-food products.

The new facility will be focused on enhancing the system for commercial delivery as a solution for cellulosic feedstock processing in ethanol production. Equipment and feedstocks are being acquired to analyze the throughput capacity, energy requirements, and scalability of the system. This equipment can improve the efficiencies of cellulosic feedstock and provide ethanol producers with an alternative to corn. Initial experiences with components of the system lead the company to believe that the system will significantly improve process times and net ethanol yield from cellulosic feedstocks

An ethanol production plant, capable of producing fifty million gallons of ethanol per year, is projected to continuously require the equivalent of a truckload of sorghum every five minutes. Initial experiences with components of the system indicate that large quantities could be processed with cost effective energy consumption. The focus of the R&D facility will be to quantify the precise parameters of the systems operations and evaluate the engineering requirements to scale the unit to handle the quantities of feedstock that a commercially viable cellulosic ethanol plant would require.

Related Fields To Cellulosic Ethanol

*Biology
*Biotechnology
*Agriculture
*Myriophyllum
*Butanol fuel

Development timeline

* 1998 patent|US|5811381| [http://www.dyadic.com/pdf/patent_us1.pdf Cellulase Compositions And Methods Of Use. - Methods of use for the cellulase compositions of the saccharification of lignocellulose biomass from agriculture, forest products, muicipal solid waste and other sources.]
* 2003 patent|US|6573086| [http://www.dyadic.com/pdf/patent_us6.pdf Transformation System In The Field Of Filamentous Fungal Hosts. - Engineering filamentous fungi to produce low cost efficient enzyme mixtures to convert lignocellulose (biomass or energy crops) into fermentable sugars such as glucose and xylose]
* 2005: [http://www.smalltimes.com/articles/article_display.cfm?Section=ARCHI&C=Bio&ARTICLE_ID=267793&p=109 Fungus functions as lab and factory for protein]
* 2006
** [http://www.dyadic.com/pdf/Wileyarticle.pdf Design of Highly Efficient Cellulase Mixtures for Enzymatic Hydrolysis of Cellulose]
** patent|US|7122330| [http://www.dyadic.com/pdf/pat7122330.pdf High-Throughput Screening of Expressed DNA Libraries in Filamentous Fungi—use of robotics to identify and create new and better genes that encode for cellulase and hemicellulase enzymes that can be inserted into fungi or other organisms for use in the conversion of lignocellulose (biomass or energy crops) into fermentable sugars]
** BIO CEO and Investor Conference, February 13-15, 2006 at The Waldorf Astoria Hotel in New York City.
** [http://pubs.acs.org/cen/employment/84/8414biotech.html Industrial Biotech Gains Momentum, Growth of commercial enzyme-mediated processes points to the future of the chemical industry;] April 3, 2006
** [http://www.evworld.com/article.cfm?archive=1&storyid=1005&first=2990&end=2989 Exploiting Fungal Factories for Future Energy]
** [http://www.sptimes.com/2006/09/10/Business/Cradle_of_innovation.shtml Cradle of innovation] Although it's starting late, Florida has minds and the raw materials to become a leader in alternative energy research and a.. September 10, 2006
** - [http://www.chicagotribune.com/business/chi-0610130128oct13,0,7209827.story?page=1&track=rss Beyond corn: Ethanol's next generation, Scientists seek cheap, plentiful energy alternatives] October,13 2006
** Bear Stearns Second Annual Commodities and Capital Goods Conference, Wednesday, November 29 and Thursday, November 30, 2006 - Biofuels – Prospect of Future Technologies
** cite journal |author=Sanderson K |title=US biofuels: a field in ferment |journal=Nature |volume=444 |issue=7120 |pages=673–6 |year=2006 |month=Dec |pmid=17151628 |doi=10.1038/444673a |url=http://www.nature.com/nature/journal/v444/n7120/full/444673a.html
** [http://www.iogen.ca/news_events/iogen_news/BusinessWeekDECEMBER_18.pdf Put A Termite In Your Tank] December 18, 2006
* 2007
** Ethanol Producer Magazine January 2007 " [http://www.dyadic.com/pdf/EthanolProducer_Enzymes01012007.pdf The Discoverer's Game] "
** BIO CEO & Investor Conference February 12, 2007 at the Waldorf-Astoria Hotel in New York City,
** [http://www.greenpowerconferences.com/wbm/documents/BrochureWorldBiofuelsMarkets_024.pdf World Biofuels Markets Congress] , Brussels, Belgium March 12-14 2008
** Dyadic, Int.: [http://www.brightcove.tv/title.jsp?title=507310172&channel=452349432&lineup=505319769 The Making of Cellulosic Ethanol]
** [http://www.nytimes.com/2007/04/17/business/17ethanol.html?pagewanted=1&adxnnlx=1195016548-2GcjH7HGw1oEmssIyEi6Aw The Energy Challenge A Renewed Push for Ethanol, Without the Corn,] "The New York Times", April 17, 2007
* 2008: Michigan’s first Center of Energy Excellence - [http://www.admin.mtu.edu/urel/news/media_relations/697/ To create the first commercially viable cellulosic ethanol plant.]

See also

* Algae fuel
* Biofuel
* Biorefinery
* Butanol
* Butanol fuel
* Candida tropicalis
* Carbon Negative
* Cellulosic ethanol commercialization
* Cellulosome
* China Resources Alcohol Corporation
* Coskata
* Non food crops
* Range Fuels
* SunOpta
* thermophilic
* Treethanol
* Verenium Corporation

References

External links

* [http://www.planetark.com/dailynewsstory.cfm/newsid/46338/story.htm Switchgrass Fuel Yields Bountiful Energy] .
* [http://www.hort.purdue.edu/newcrop/ncnu02/v5-017.html Ethanol From Cellulose: A General Review] — P.C. Badger, 2002
* US DOE:
** [http://www.sc.doe.gov/ober/ober_top.html Office of Biological and Environmental Research (OBER)] .
** [http://www.eere.energy.gov/biomass/enzymatic_hydrolysis.html Cellulosic ethanol production via enzymatic hydrolysis]
** [http://www.eere.energy.gov/biomass/synthesis_gas_fermentation.html/ Cellulosic ethanol production via synthesis gas fermentation]
** [http://www.energy.gov/news/4827.htm DOE Selects Six Cellulosic Ethanol Plants for Up to $385 Million in Federal Funding February 28, 2007]
* [http://www.biobasednews.com/ BiobasedNews.com]
* [http://www.investincellulosicethanol.com News and investor information for cellulosic ethanol companies.]
* [http://www.rmi.org/sitepages/pid1157.php Rocky Mountain Institute page on ethanol]
* The [http://www.journeytoforever.org/biofuel_library/WoodEthanolReport.html "Wood-Ethanol Report"] by Environment Canada, 1999, re-published by the [http://www.journeytoforever.org/ Journey to Forever] web site.
* [http://energy.senate.gov/public/index.cfm?IsPrint=true&FuseAction=Hearings.Testimony&Hearing_ID=1565&Witness_ID=4427 US Senate committee hearing statement from Dr. Michael Pacheco] , including current costs and expected costs of producing cellulosic ethanol.

* [http://grist.org/news/maindish/2006/12/04/montenegro/ The numbers behind ethanol, cellulosic ethanol, and biodiesel in the U.S.] by Maywa Montenegro, Grist Magazine, 4 December 2006
* [http://www.wzw.tum.de/mbiotec/cellmo.htm A list of cellulolytic bacteria]
* [http://www.nrel.gov/biomass National Renewable Energy Laboratory, Research Advances – Cellulosic Ethanol.]
* [http://www.forestbioproducts.umaine.edu/project_enzymes_biopulping.php New Enzymes for Biopulping]
* [http://www.fpl.fs.fed.us USDA Forest Products Laboratory — Research you can use!]
* [http://www.CellulosicRoundtable.com See what industry insiders are saying about the cellulosic ethanol sector]
* [http://www.kk.org/outofcontrol/ch10-f.html INDUSTRIAL ECOLOGY - CH10 - Out of Control by Kevin Kelly]