Cellulosic ethanol (also called lignocellulosic ethanol, or ceetoh) 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 and woodchip are some of the more popular cellulosic materials for ethanol production. Cellulosic ethanol is chemically identical to ethanol from other sources, such as corn starch or sugar, but has the advantage that the lignocellulose raw material is highly abundant and diverse. However, it differs in that it 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 is the major biomass material being studied today, due to its 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. Whether distilled from agricultural crops such as corn, wheat, barley or created from cellulose, ethanol is ethyl alcohol; it is identical in chemical composition regardless of the source thus calling it cellulosic ethanol is initially misleading because it (cellulosic ethanol) is no different physically from corn ethanol or wheat ethanol. In essence, the term is used to describe the process for producing the alcohol rather than specifying a type of ethanol.

The ground of North American forests is littered with millions of tons of cellulose-containing waste-wood including bark, branches, and leaf litter which has fallen from trees. This material could be harvested and converted into ethanol fuel. The processes that produce lumber products also generate cellulose waste that is discarded that could be used to produce cellulosic ethanol.

There are at least two methods of production of cellulosic ethanol (see "Production methods", below):

• Cellulolytic method: hydrolysis followed by fermentation of the generated free sugars.
• Gasification, which produces synthesis gas that can be converted to ethanol by fermentation or thermochemical catalysis (e.g., the Fischer-Tropsch process).

Neither process generates toxic emissions when it produces ethanol.

Cellulosic ethanol production currently exists at "pilot" and "commercial demonstration" scale, including a plant in China engineered by SunOpta Inc. and owned and operated by China Resources Alcohol Corporation that is currently producing cellulosic ethanol from corn stover (stalks and leaves) at a continuous, 24-hour per day rate.

According to US Department of Energy studies 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. A study by Nobel Prize winner Paul Crutzen, find "net climate warming" effect of ethanol produced from corn, rapeseed (canola), and sugarcane when compared to oil.^[1]

Ethanol, if made from cellulose, emits 80 percent less global warming pollution than gasoline.^[2]

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.^[3][4][5]

In April 2004, Iogen Corporation, a Canadian biotechnology firm, became the first business to commercially sell cellulosic ethanol, though in very small quantities. The primary consumer thus far has been the Canadian government, which, along with the United States government (particularly the Department of Energy's National Renewable Energy Laboratory), has invested millions of dollars into assisting the commercialization of cellulosic ethanol.

Another company which appears to be nearing commercialization of cellulosic ethanol is Spain's Abengoa Bioenergy.^[6] Abengoa has and continues to invest heavily in the necessary technology for bringing cellulosic ethanol to market. Using process and pre-treatment technology from SunOpta Inc.(NASDAQ: STKL) (multiple classs-action lawsuits have been brought by shareholders against SunOpta and it is reportedly facing bankruptcy), Abengoa is building a 5 million gallon cellulosic ethanol facility in Spain and has recently entered into a strategic research and development agreement with Dyadic International, Inc. (AMEX: DIL), to create a new and better enzyme mixture which may be used to improve both the efficiencies and cost structure of producing cellulosic ethanol.

On December 21, 2006, SunOpta Inc. announced a Joint Venture with GreenField Ethanol, Canada's largest ethanol producer. The joint venture will build a series of large-scale plants that will make ethanol from wood chips, with SunOpta Inc. and GreenField each taking 50% ownership. The first of these plants will be 10 million gallons per year, which appears to be the first true "commercial scale" cellulosic ethanol plant in the world. Under 1 million gallons per year (MMgy) is considered "Pilot Scale", greater than 1 MMgy but less than 10 MMgy is defined as "commercial demonstration", while a plant that produces 10 MMgy per year or greater is true "commercial scale". Despite the multiple commercial demonstration cellulosic ethanol plants SunOpta has been involved with, media reports continue to state that cellulosic ethanol is an unproven, "experimental" technology. The 10 MMgy SunOpta/GreenField cellulosic ethanol plant is intended to demonstrate that large-scale cellulosic ethanol is commercially viable immediately.

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.^[7]

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.^[8] Construction began in November, 2007.^[9]

Production methods

There are two ways of producing alcohol from cellulose:

• Cellulolysis processes which consist of hydrolysis on pretreated lignocellulosic materials 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:

1. A "pretreatment" phase, to make the lignocellulosic material such as wood or straw amenable to hydrolysis,
2. Cellulose hydrolysis (cellulolysis), to break down the molecules into sugars;
3. Separation of the sugar solution from the residual materials, notably lignin;
4. Microbial fermentation of the sugar solution;
5. 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.^[10] By far, most pretreatments are done through physical or chemical means. In order to achieve higher efficiency, some researchers seek to incorporate both effects.^[11]

To date, the available pretreatment techniques include acid hydrolysis, steam explosion, ammonia fiber expansion, alkaline wet oxidation and ozone pretreatment.^[12] 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.^[13] 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.^[14] In fact, Ammonia Fiber Expansion (AFEX) is the sole pretreatment which features promising pretreatment efficiency with no inhibitory effect in resulting hydrolysate^[15]

Cellulolytic processes

The cellulose molecules are composed of long chains of sugar molecules of various kinds. 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.^[16] Dilute acid may be used under high heat and high pressure, or more concentrated acid can be used at lower temperatures and atmospheric pressure. 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. By far, all major pretreatment methods, including dilute acid pretreatment, require enzymatic hydrolysis step to achieve high sugar yield for ethanol fermentation^[15]

A start-up American environmental company Wise Landfill Recycling Mining, has discovered a purely organic hydrolysis process for cellulosic ethanol that generates 4.4 times the ethanol product from trash, at a rate that is oil-independent capable^[17] without process-intensive genetically modified microbes. Their method also boasts of being not merely carbon neutral, but carbon negative^[18] Wise Landfill is led by CEO and Applied Quantum Politics internet author^[19], Stephen L. Rush.

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

Iogen Corporation is a Canadian producer of enzymes for an enzymatic hydrolysis process that uses "specially engineered enzymes".^[20] The raw material (wood or straw) has to be pre-treated to make it amenable to hydrolysis.

Trichoderma reesei is used by Iogen Corporation.

Another Canadian company, SunOpta Inc. 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 scale plants in the world:^[21] 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 government 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, Inc. (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 (NASDAQ: VRNM), the new name of recently merged Diversa and Celunol Corporations, 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. Vernium is the first publicly traded company with integrated, end-to-end capabilities to make cellulosic biofuels.

Microbial fermentation

Main article: Ethanol 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.^[22] 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^[23] and arabinose,^[24] and even both together.^[25] 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.^[26]

Gasification process (thermochemical approach)

Fluidized Bed Gasifier in Güssing Burgenland Austria

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”.^[27] 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:

1. Gasification — Complex carbon based molecules are broken apart to access the carbon as carbon monoxide, carbon dioxide and hydrogen are produced
2. Fermentation — Convert the carbon monoxide, carbon dioxide and hydrogen into ethanol using the Clostridium ljungdahlii organism
3. 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^[28]

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.^[29] This process can also generate other types of liquid fuels, an alternative concept under investigation by at least one biofuels company^[30]

Economics

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.^[31] 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 in capital investment costs for pilot plants; future capital costs are expected to be lower. Corn to ethanol plants cost roughly $1–3/annual gallon capacity.^[32][33]

The quest for alternative sources of energy has provided many ways to produce electricity, such as wind farms, hydropower, or solar cells. However, about 40% of total energy consumption is dedicated to transportation (i.e., cars, planes, lorries/trucks, etc.) 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 plants. Since cellulose cannot be digested by humans, the production of cellulose does not compete with the production of food. 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.

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 materials that could be used to create ethanol are thrown away each year. This includes 36.8 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 and wheat straw.^[34] 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.

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.^[35]

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 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 is comprised 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 that can and should be transformable into cellulosic ethanol^[34] because they are the leading cause of methane plumes. Methane, a greenhouse gas, is 21 times more potent than carbon-dioxide^[36].

Reduction of the disposal of solid waste through celulosic ethanol conversion would reduce solid waste disposal costs by local and state governments. It is estimated that each person in the US throws away 4.4 lbs of trash each day, of which 37% contains waste paper which is comprised of cellulose. That computes to 244 thousand tons per day of discarded waste paper that contains cellulose. [300 million people × 4.4 lbs per person × 37% is paper / 2000 lbs per ton] The raw material to produce cellulosic ethanol is not only free, it has a negative cost — i.e., you get paid to take it away^[37].

An environmental company Wise Landfill Recycling Mining, expects to start generating cellulosic ethanol product from trash early 2008^[38]. Their method also boasts of being not merely carbon neutral, but oil independent^[39].

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. 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.

Environmental effects: corn-based vs. grass-based

Today, there is 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 billion acres of land, 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.^[40] A recent study done by the University of Tennessee reported that as many as 100,000,000 acres (400,000 km²)(154 thousand sq. miles ) of cropland and pasture will need to be allocated to switchgrass production in order to offset petroleum use by 25 percent.^[41]

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.^[42] 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 (www.ilsr.org) 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 $3.00 per gallon for Regular Gasoline (which is subsidized and taxed).^[43]

One of the major reasons for increasing the use of biofuels is to reduce greenhouse gas emissions.^[44] In respect 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.^[45] 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.^[41] 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.^[45] 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.^[42]

It takes 1.2 gallons of fossil fuel to produce 1 gallon of ethanol from corn. 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.^[41] Cellulosic ethanol yields 80 percent more energy than is required to grow and convert it.^[46] 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.^[47] 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.^[41] 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.^[48] 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 that is known for its hardiness and rapid growth. This perennial grows during the warm season of the year and grows to 2-6 feet tall. Switchgrass can be grown in most parts of the United States, including swamplands, plains, streams, and along the shores. It is resistant to many diseases and pests and can produce high yields with low applications of fertilizer and other chemicals. It is also tolerant to poor soils, flooding, and drought and improves soil quality and prevents erosion.^[49]

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.^[49]

Prominent cellulosic ethanol researchers

• Bruce Dale, Michigan State University
  • 2007 USDA Sterling B. Hendricks memorial lecturer[1]
  • 1996 Charles D. Scott awardee [2]
  • The Inventor of Ammonia Fiber Expansion (AFEX) pretreatment [3]
  • Fourteen US international patent holder [4]
  • Among the group of ten experts from industry, academia and government lab who was invited to brief President Bush on biofuels [5]
• Nancy Ho, Purdue University
• Mark Holtzapple, Texas A&M University
• Lonnie Ingram, University of Florida IFAS
  • 2007 Charles D. Scott awardee[6]
  • Member of U.S. National Academy of Sciences (2001)[7]
  • Fellow of Society of Industrial Microbiology (2001)[8]
  • Twelve U.S. Patents holder including the landmark patent 5,000,000 on an important breakthrough on metabolic engineering of Escherichia coli to utilize virtually all sugars from lignocellulosic materials for ethanol production [9]
• Lee Lynd, Dartmouth College
• J.H. David Wu, University of Rochester
• Eckhard Boles, Goethe-University of Frankfurt
  • Seven international patents holder including the patent describing the first recombinant yeast able to ferment the lignocellulosic sugar L-arabinose [10][11]
• Charles E. Wyman, University of California, Riverside
• Mark A. Emalfarb, Founder of Dyadic International, Inc.

Development timeline

• 1998 US Patent # 5,811,381 - 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.[12]
• 2003 US Patent # 6,573,086 - 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 fermntable sugars such as glucose and xylose [13]
• 2005 - Fungus functions as lab and factory for protein [14]
• 2006 - Design of Highly Efficient Cellulase Mixtures for Enzymatic Hydrolysis of Cellulose [15]
• 2006 - US Patent # 7,122,330 - 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 [16]
• 2006 - BIO CEO and Investor Conference, February 13-15, 2006 at The Waldorf Astoria Hotel in New York City.
• 2006 - Industrial Biotech Gains Momentum, Growth of commercial enzyme-mediated processes points to the future of the chemical industry; April 3, 2006 [17]
• 2006 - Exploiting Fungal Factories for Future Energy [18]
• 2006 - Cradle of innovation Although it's starting late, Florida has minds and the raw materials tobecome a leader in alternative energy research and a.. September 10, 2006 [19]
• - Beyond corn: Ethanol's next generation, Scientists seek cheap, plentiful energy alternatives October,13 2006 [20]
• 2006 - Bear Stearns Second Annual Commodities and Capital Goods Conference, Wednesday, November 29 and Thursday, November 30, 2006 - Biofuels – Prospect of Future Technologies
• 2006 - "US biofuels: A field in ferment" - Nature 444, 673-676 (7 December 2006) | doi:10.1038/444673a; Published online 6 December 2006 [21]
• 2006 - Put A Termite In Your Tank December 18, 2006 [22]
• 2007 - Ethanol Producer Magazine January 2007 "The Discoverer's Game" [23]
• 2007 - BIO CEO & Investor Conference February 12, 2007 at the Waldorf-Astoria Hotel in New York City,
• 2007 - World Biofuels Markets Congress, Brussels,Belgium March 12-14 2008 - [24]
• 2007 - Dyadic, Int.: The Making of Cellulosic Ethanol[25]
• 2007 -The Energy Challenge A Renewed Push for Ethanol, Without the Corn, NY Times April 17, 2007 [26]

See also

• Algae fuel
• Biofuel
• Biorefinery
• Butanol
• Butanol fuel
• Carbon Negative
• Cellulosic ethanol commercialization
• Cellulosome
• Coskata
• Non food crops
• SunOpta
• Treethanol

References

External links

• Switchgrass Fuel Yields Bountiful Energy.
• Grain and cellulosic ethanol: History, economics, and energy policy, Biomass and Bioenergy, Barry D. Solomon, Justin R. Barnes and Kathleen E. Halvorsen (2007) In Press, Corrected Proof, Available online 13 March 2007.
• Ethanol From Cellulose: A General Review - P.C. Badger, 2002
• Cellulosic Ethanol Companies, News and Stock / Investor Information
• US DOE page on cellulosic ethanol production via enzymatic hydrolysis
• US DOE page on cellulosic ethanol production via synthesis gas fermentation
• Rocky Mountain Institute page on ethanol
• The "Wood-Ethanol Report" by Environment Canada, 1999, re-published by the Journey to Forever web site.
• US Senate committee hearing statement from Dr. Michael Pacheco, including current costs and expected costs of producing cellulosic ethanol.
• DOE Selects Six Cellulosic Ethanol Plants for Up to $385 Million in Federal Funding February 28, 2007
• The numbers behind ethanol, cellulosic ethanol, and biodiesel in the U.S. by Maywa Montenegro, Grist Magazine, 4 December 2006
• A list of cellulolytic bacteria
• Range Fuels, cellulosic ethanol.
• National Renewable Energy Laboratory, Research Advances – Cellulosic Ethanol.
• New Enzymes for Biopulping
• USDA Forest Products Laboratory -- Research you can use!

Three phases of ethanol commercialization are emerging. The first phase is based on traditional domestic production, economics and feedstocks - generally grown and sold near geographically agricultural areas. The second phase, based on the fast-changing globalization of ethanol trade, will involve multiple feedstock production, non-food fuel crops, and expanding production areas.^[1] The third phase is based on cellulosic ethanol commercialization which hopes for higher fuel production and investment returns per acre at lower costs.^[1] If the potentials of cellulosic ethanol commercialization are realized, then ethanol fuel may replace 20% of gasoline consumption in the USA, China and India by the year 2020.^[1]

Cellulosic ethanol production

Main article: Cellulosic ethanol

Cellulosic ethanol is a new approach which can be produced from a diverse array of feedstocks. Instead of just taking the grain from wheat and grinding that down to get starch and gluten, then taking the starch, cellulosic ethanol production involves the use of the whole crop. This new approach will double yields and also have a smaller carbon footprint because the amount of energy-intensive fertilisers and fungicides will remain the same, for a higher output of usable material.^[2][3] Many regions can be a producer of this fuel. Production of cellulosic ethanol is therefore viewed as a resource that can improve national energy security in countries without significant fossil fuel reserves, the environment and greenhouse gas mitigation, and rural economic development.^[3]

Cellulosic ethanol commercialization by country

Canada

In Canada, Iogen Corp. is a leading developer of cellulosic ethanol process technology. Iogen has developed a proprietary process and operates a demonstration-scale plant in Ontario. The facility has been designed and engineered to process 40 tons of wheat straw per day into ethanol using enzymes made in an adjacent enzyme manufacturing facility. In 2004, Iogen began delivering its first shipments of cellulosic ethanol into the marketplace. In the near term, the company intends to commercialize its cellulose ethanol process by licensing its technology broadly through turnkey plant construction partnerships. The company is currently evaluating sites in the United States and Canada for its first commercial-scale plant.^[4]

China

Cellulosic ethanol production currently exists at "pilot" and "commercial demonstration" scale, including a plant in China engineered by SunOpta Inc. and owned and operated by China Resources Alcohol Corporation that is currently producing cellulosic ethanol from corn stover (stalks and leaves) on a continuous, 24-hour per day basis.^[5]

Spain

Abengoa continues to invest heavily in the necessary technology for bringing cellulosic ethanol to market. Utilizing process and pre-treatment technology from SunOpta Inc., Abengoa is building a 5 million gallon cellulosic ethanol facility in Spain and have recently entered into a strategic research and development agreement with Dyadic International, Inc. (AMEX: DIL), to create new and better enzyme mixtures which may be used to improve both the efficiencies and cost structure of producing cellulosic ethanol.^[5]

United Kingdom

A $400 million investment programme to cover the construction of a world scale ethanol plant and a high technology demonstration plant to advance development work on the next generation of biofuels has been announced by BP, Associated British Foods (ABF) and DuPont. The bioethanol plant will be built on BP's existing chemicals site at Saltend, Hull. Due to be commissioned in late 2009, it will have an annual production capacity of some 420 million litres from wheat feedstock.^[6]

United States

President George W. 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 accepted that the maximum production of ethanol from corn starch is 15 billion gallons per year, implying a mandated production of some 20 billion gallons per year of cellulosic ethanol by 2017. Bush's plan includes $2 billion dollars funding for cellulosic ethanol plants, with an additional $1.6 billion announced by the United States Department of Agriculture on January 27, 2007.^[5]

The U.S. Department of Energy (DOE) is promoting the development of ethanol from cellulosic feedstocks as an alternative to conventional petroleum transportation fuels. Programs sponsored by DOE range from research to develop better cellulose hydrolysis enzymes and ethanol-fermenting organisms, to engineering studies of potential processes, to co-funding initial ethanol from cellulosic biomass demonstration and production facilities. This research is conducted by various national laboratories, including the National Renewable Energy Laboratory (NREL), Oak Ridge National Laboratory (ORNL) and Idaho National Engineering and Environmental Laboratory (INEEL), as well as by universities and private industry. Engineering and construction companies and operating companies are generally conducting the engineering work.^[7]

The maturing corn-to-ethanol industry has many similarities to the emerging lignocellulose-to-ethanol industry. It is certainly possible that some of the early practitioners of this new technology will be the current corn ethanol producers.^[7]

On February 7, 2007 Range Fuels, Inc. announced it would build the first cellulosic ethanol plant in the United States in Treutlen County, Georgia. Founded by Menlo Park, California-based Khosla Ventures, Range Fuels estimates that this plant—combined with others to follow—will have the capacity to produce over 1 billion gallons of ethanol per year. The first plant will create over 70 new jobs for the area. Range Fuels also reports that cellulosic ethanol generate 16 times more energy than is required to create it. The plant could be the first step towards expanding the United States’ energy and fuel diversity and finding a cost effective alternative to petroleum.^[8]

Environmental issues

Cellulosic ethanol and grain-based ethanol are, in fact, the same product, but many scientists believe cellulosic ethanol production has distinct environmental advantages over grain-based ethanol production. On a life-cycle basis, ethanol produced from agricultural residues or dedicated cellulosic crops has significantly lower greenhouse gas emissions and a higher sustainability rating than ethanol produced from grain.^[9]

According to US Department of Energy studies conducted by the Argonne Laboratories of the University of Chicago, cellulosic ethanol reduces greenhouse gas emissions (GHG) by 85% over reformulated gasoline. By contrast, starch ethanol (e.g., from corn), which usually uses natural gas to provide energy for the process, reduces greenhouse gas emissions by 18% to 29% over gasoline.^[10]

Criticism

Critics such as Cornell University professor of ecology and agriculture David Pimentel and University of California at Berkeley engineer Ted Patzek question the liklihood of environmental, energy, or economic benefits from cellulosic ethanol technology. [1] [2] [3]

Future prospects

As crude oil prices continue to rise, advocates of cellulosic ethanol production prepare to bridge the gap between demonstration-scale plants and true commercial-scale facilities.^[11]

See also

• VeraSun Energy
• Diversa

References

External links

• List of U.S. Ethanol Plants
• "Q Microbe" Shows Promise for Advancing Cellulosic Ethanol
• US DoE puts up $33.8m to support cellulosic biofuel
• POET to present on Commercial Cellulosic Project in Washington DC
• Texas A&M, Ceres To Develop Sorghum For Cellulosic Ethanol
• Merrill Lynch Introduces Biofuels Indices
• Biofuel Breakthroughs & the Cellulosic Fuels Revolution
• Two New Reports Highlight Ethanol Industry
• Xethanol Increases Cellulosic Ethanol Production Rates
• Cellulosic Ethanol Plant Open in Wyoming