Cellulosic ethanol

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Bioenergy > Technologies > Biochemical technologies > Cellulosic ethanol

Cellulose (C₆H₁₀O₅)_n is a complex carbohydrate (a long-chain polymeric polysaccharide of beta-glucose) that forms the main constituent of the cell wall in most plants. It is the most abundant form of living terrestrial biomass. Cellulosic biomass has three primary components: cellulose, hemicellulose, and lignin. Lignin and cellulose, considered together, are termed lignocellulose, which (as wood) is argued to be one of the most common biopolymers on Earth. While most animals, including humans can not digest cellulose, some, particularly ruminants (such as cows) and termites, can digest cellulose with the help of symbiotic micro-organisms.

Relative GHG emissions reduction potentials for ethanol by feedstock type. These estimates refer to direct emissions only, and do not include emissions from land use change. Source: Worldwatch Issue Brief: U.S. Biofuels: Climate Change and Policies (PDF file)

Cellulosic ethanol

While ethanol production from sugars and starches has been done for thousands of years, the technology to produce ethanol from cellulose is relatively modern and is not yet fully commercialized.

• The conversion process uses enzymes, like cellulase, to break cellulose down to sugars. It is also possible to produce biofuels from cellulosic feedstocks through gasification and biomass-to-liquids technologies.¹
  • The high cost of these enzymes is one of the main limitations on the commercialization of cellulosic ethanol. (Citation needed)

• Cellulosic ethanol has many advantages however:

• The use of waste biomass, such as forestry wastes, or by-products of the paper industry, allows for ethanol production without increasing agricultural production.¹

• Cellulosic biomass from fast-growing perennial energy crops, such as short rotation woody crops and tall grass crops, can be grown on a much wider range of soil types, where the extensive root systems that remain in place with these crops help prevent erosion, and increase carbon storage in soil.¹

• Energy crops can often be grown on poorer soils.¹
  • However, high biomass yields will only be achieved on good soils with sufficient water supply.¹

• Cellulosic biomass can be easier to store for long periods of time.¹

• Compared to conventional crops, where only small portion of the plant can be used for biofuel production, perennial energy crops can supply much more biomass per hectare of land, since nearly the entire plant can be used as feedstock.¹

Events

• 3-5 August 2010, Tifton, Georgia, USA: Southeast Bionenergy Conference. (Themes: aviation, biomass pellets, cellulosic ethanol, ethanol, second generation biofuels, waste)

• 9-10 November 2010, San Francisco, California, USA: Advanced Biofuels Markets. (Themes: advanced biofuels, algae, bio-butanol, cellulosic ethanol, drop-in fuels, feedstocks, markets, solar liquid fuels)

See the archive of past Cellulosic ethanol-related events.

Publications

See books, reports, scientific papers, position papers and websites for additional useful resources.

• Global: Status of Next Generation Biofuels Facilities - 26-page September 2009 report (cost: $1,595.00) issued by Hart Energy's Global Biofuels Center.
  • From the description: "Next generation biofuels have received tremendous fanfare...as a crucial part of the next steps toward energy security, reducing dependence on petroleum products and environmental well-being....Be it cellulosic ethanol, renewable diesel, biomass-to-liquids (BTL) or Fischer Tropsch liquids, made from feedstocks such as agricultural/forest/municipal solid wastes, grasses, woods, waste paper and algae, next generation biofuels are still largely under R&D."[1]

• Climate change and health costs of air emissions from biofuels and gasoline by Jason Hill, et al. December 2008. The report analyzes the environmental impacts of energy use on society. It also discusses the benefits, including health costs and GHG reduction, of shifting from gasoline to cellulosic ethanol production.

• Grass biofuels 'cut CO2 by 94%', 8 January 2008, by BBC News: A new report by US researchers has found that fast-growing "switchgrass-derived ethanol produced 540% more energy than was required to manufacture the fuel" and "delivers vast savings of carbon dioxide emissions compared with petrol." The paper, "Net energy of cellulosic ethanol from switchgrass (PDF file)" in the Proceedings of the National Academy of Sciences, analyzed all of the energy input factors, including "nitrogen fertiliser, herbicides, diesel and seed production."

• Induction of the celC operon of Clostridium thermocellum by laminaribiose by Michael Newcomb, Chun-Yu Chen, and J. H. David Wu; PNAS, 5 January 2007.

• Cellulosic Ethanol - Biofuel Beyond Corn by Nathan S. Mosier; Department of Agriculture and Biological Engineering, Purdue University, December 2006.

• Making Cellulosic Ethanol Happen: Good and Not So Good Public Policy (pdf) by David Morris; Institute for Local Self-Reliance, January 2007.

• Breaking the Biological Barriers to Cellulosic Ethanol: A Joint Research Agenda - A Research Roadmap Resulting from the Biomass to Biofuels Workshop, December 7–9, 2005, Rockville, Maryland; USDOE.

• Biomass as feestock for a Bioenergy and Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual Supply - A joint study by USDA and USDOE, April 2005.

• Carbon-Negative Biofuels from Low-Input High-Diversity Grassland Biomass (subscription required) by David Tilman, Jason Hill, and Clarence Lehman; Science Vol. 314. no. 5805, pp. 1598-1600, 8 December 2006.

• Ethanol from Cellulose: A General Review (PDF) by P.C. Badger; reprinted from: Trends in new crops and new uses, J. Janick and A. Whipkey (eds.). ASHS Press, Alexandria, VA, 2002.

News

2010

• New CBO Report Examines Biofuels Tax Incentives, 16 July 2010 by Mackinnon Lawrence: "CBO releases report this week assessing biofuel incentives. Study finds that biofuel subsidies, costs associated with reducing petroleum use and GHG emissions vary by fuel."
  • "First, after making adjustments for the different energy contents of the various biofuels and the petroleum fuel used to produce them, the report finds that producers of ethanol made from corn receive 73 cents to provide an amount of biofuel with the energy equivalent to that in one gallon of gasoline. On a similar basis, producers of cellulosic ethanol receive $1.62, and producers of biodiesel receive $1.08."
  • "Second, the report finds reducing petroleum use costs taxpayers anywhere from $1.78 – 3.00 per one gallon of gasoline, again, depending on the type of fuel."
  • "Third, the costs to taxpayers of reducing greenhouse gas emissions varies from $275 per metric ton of CO2e for cellulosic, $300 per metric ton for CO2e for biodiesel, and about $750 per metric ton of CO2e for ethanol . NOTE: the CBO estimates do not reflect any emissions associated with land use change (direct or indirect)."
  • "Domestic Fuel reports this week that the Renewable Fuels Association (RFA) asserts the report provides no comparison to other technologies or types of biofuels against the destruction that goes hand in hand with fossil fuel production."[2]
    • Read the full report here: Using Biofuel Tax Credits to Achieve Energy and Environmental Policy Goals (PDF)

• New Federal Policies Needed to Jump-Start Clean Advanced Biofuels Industry, 14 June 2010 by The Union of Concerned Scientists: "The federal government needs to adopt a suite of new policies to spur production in the stalled advanced biofuels industry, according to a report, The Billion Gallon Challenge, released today by the Union of Concerned Scientists (UCS).
  • "Advanced cellulosic biofuels – made from grasses, woodchips, wastes and other non-food sources – release dramatically less pollution than gasoline or corn ethanol. Reforming production tax credits for biofuels and providing new loan guarantees, investment tax credits and other financial incentives would spark investment in cellulosic biofuels, cut oil consumption, reduce global warming pollution, and ultimately save taxpayers money, the report found."
  • "Currently, cellulosic biofuels are falling far short of the mandated levels. In 2010, the standard requires fuel suppliers, largely oil companies, to purchase 100 million gallons of cellulosic biofuel, but the Environmental Protection Agency (EPA) had to lower this target to just 6.5 million gallons due to a lack of supply."[3]
    • The Billion Gallon Challenge

• ZeaChem Celebrates Groundbreaking Of Biorefinery In Boardman, Oregon, 2 June 2010 by ZeaChem: "ZeaChem Inc., a developer of biorefineries for the conversion of renewable biomass into sustainable fuels and chemicals, held a groundbreaking ceremony today for its 250,000 gallon-per-year biorefinery in Boardman, Oregon."
  • "The plant will initially use ZeaChem’s core technology... to produce ethyl acetate, a salable chemical intermediate and precursor to cellulosic ethanol."
  • "Using an American Recovery and Reinvestment Act (ARRA) grant from the U.S. Department of Energy (DOE), the company will add the cellulosic ethanol production capability to come online in 2011."
  • "ZeaChem has a contract with GreenWood Resources (GWR), a Portland-based timberland investment manager, to obtain sustainable hybrid poplar tree feedstock from the nearby farms held under GreenWood Tree Farm Fund, LP. Because the technology is feedstock agnostic, ZeaChem will also process trials of herbaceous crops, agricultural residuals and other renewable biomass resources."[4]

• DOE, USDA Announce Funding for Biomass Research and Development Initiative, 6 May 2010, press release by the Department of Energy: "The U.S. Departments of Energy (DOE) and Agriculture (USDA) today jointly announced up to $33 million in funding for research and development of technologies and processes to produce biofuels, bioenergy and high-value biobased products, subject to annual appropriations."
  • "DOE also released today a new video which showcases how cellulosic biofuel technologies can help decrease U.S. dependence on foreign oil, spur growth in the domestic biofuels industry, and provide new revenue opportunities to farmers in many rural areas of the country."
  • "The video, shot at a harvesting equipment demonstration in Emmetsburg, Iowa, highlights a new way of producing ethanol from the cellulose fibers in corn cobs, not from the corn kernels. The technology generates a new opportunity for farmers to harvest and sell the cobs that they’d normally leave in the field."[5]

• Canadian government orders biofuels study, April 2010 by Holly Jessen, Ethanol Producers Magazine:"Environment Canada solicited companies to complete an assessment of the ecological footprint of biofuel production facilities in Canada."
  • "The Canadian government is following through with its commitment to establish regulations for renewable fuels in the fuel supply... 'The strategy requires 5 percent renewable content of gasoline by 2010,' the spokesperson said. 'Canada also intends to implement a requirement for 2 percent renewable content in diesel fuel and heating oil by 2011, or earlier, subject to technical feasibility.'"
  • "Not long after Environment Canada called for companies to submit proposals for the study, the Canadian government passed out funding to 16 clean technology companies. Sustainable Development Technology Canada announced $58 million in funding, $13 million of which was earmarked for proposed cellulosic ethanol plant projects. "[6]

• POET announces plans for 3.5 billion gallons of cellulosic ethanol in 2022, 21 April 2010 by POET: "POET, the largest producer of ethanol in the world, has made enough progress on technology and feedstock development to break ground on its first plant in Emmetsburg, Iowa later this year"
  • "'By 2022, POET plans to be responsible for 3.5 billion gallons of cellulosic ethanol production by adding the technology to our existing facilities, licensing our technology to other producers and finally, transferring our technology to other forms of biomass such as wheat straw, switchgrass and municipal waste,' Broin said. That volume would represent over 20 percent of the cellulosic ethanol mandated in the Renewable Fuel Standard."[7]

• Bill To Extend Ethanol Tax Credit Reignites Fuel vs. Food Debate, 25 March 2010 by SustainableBusiness.com: "A bill introduced in the US House last week would extend ethanol tax credits for another five years, to 2015. This tax credit is set to expire on December 31, 2010."
  • "The Renewable Fuels Reinvestment Act (RFRA), introduced by Congressman Earl Pomeroy (D-ND) and and John Shimkus (R-IL), has reignited the fuel versus food debate and intensified scrutiny on the EPA's regulations on the environmental impact of corn-based ethanol."
  • "The bill would extend the $0.45 Volumetric Ethanol Excise Tax Credit (VEETC), commonly called the blenders’ credit, and a secondary tariff on imported ethanol from countries like Brazil. It would also extend the Small Producers Tax Credit and the Cellulosic Ethanol Production Tax Credit to January 1, 2016."[8]

• USDA Announces a Guaranteed Loan to a Biorefinery to Produce Renewable Energy, 3 March 2010 by the USDA newsroom: "The U.S. Department of Agriculture today announced that Range Fuels, Inc., a Colorado based firm with a planned biorefinery located near Soperton, Ga., is the recipient of a loan guaranteed by USDA Rural Development to make cellulosic biofuel from wood chips."
  • "This project is expected to provide biorefinery jobs, construction jobs and support the timber industry."
  • "When fully operational, the plant is expected to produce an estimated 20 million gallons of cellulosic ethanol per year."[9]

See the archive of past Cellulosic ethanol-related news

References

¹Biofuels for Transportation (draft) (2006, Worldwatch Institute), p.10-12. Used with permission.

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