Ethanol From Cellulose
Cellulosic ethanol is the most promising second-generation biofuel, but the cost of production limits its viability, though costs are declining. (203) In order to qualify for a renewable identification number for cellulosic ethanol, production must meet requirements that include lifecycle greenhouse gas emissions, as determined by the Administrator, "that are at least 60 percent less than the baseline lifecycle greenhouse gas (GHG) emissions" from gasoline or diesel, whichever the fuel is replacing. (204) In June 2012, the first tradable renewable identification number was issued to Blue Sugars for cellulosic ethanol production, but the company went bankrupt in 2013. (205) The CAA requires 0.1 billion gallons of cellulosic biofuel to be used in the year 2010 and its use to increase in steps to 16.0 billion gallons in 2022. (206) The administrator of EPA is given limited power in CAA section 211(o)(4) to modify the advanced biofuel and cellulosic requirements concerning the mandated percentages of GHG reductions. Section 211(o)(7)(A) allows the Administrator to modify the utilization requirements to prevent harm to the economy, the environment, or because of inadequate production. (207) This power has been used to adjust production requirements; in 2012, the industry produced only 20,069 gallons of fuel. (208) An alternative approach proposed by EPA to deal with the industry's performance is to change the definition of cellulosic ethanol to allow more fuels to qualify as cellulosic biofuels. (209) Technical amendments to the RFS to clarify the number of cellulosic biofuel identification numbers for fuels of varying cellulosic content were promulgated on July 8, 2014. (210)
Ethanol produced from cellulose or other non-food inputs is a promising source of biofuels. It can be produced from trees and forest residues, although there is no commercial production of fuel from woody biomass except for the use of pulp and saw mill wastes to produce heat, steam, and electricity. (211) Fast growing woody crops such as hybrid willow and poplar have the potential to be feedstock for cellulosic fuel. (212) Another potential feedstock is perennial grass, such as switchgrass or Giant Miscanthus. Switchgrass is a perennial Midwest and Southeast grass with nearly three times the yield of hay. Giant Miscanthus is a native of Asia that has some use as a fuel in Europe. The advantage of perennial grasses is that they are not normally irrigated and therefore require less water, fertilizer, and pesticides than most crops, and their extensive root system reduces soil erosion and provides habitat for wildlife. (213) Some of the plants approved for renewable fuel production by EPA, such as giant reed and napier grass, are invasive species that other government agencies are trying to control. (214) Agricultural residues not specifically grown for food such as corn stover can be used to produce cellulosic ethanol, although the use of corn stover for fuel could lead to increases in soil erosion. (215) A 2007 lifecycle study found that the energy requirements for cellulosic fuel production are low for switchgrass and hybrid poplar feedstock when compared to corn crops. Other experts claim cellulosic ethanol has a 100 percent energy gain, compared to the 34 percent energy gain for corn. (216) Utilizing non-food inputs is important because if all of the United States corn harvest is devoted to ethanol production it would offset about 25 percent of national gasoline demand. (217)
An advantage of using cellulosic feedstock is that it can be grown on marginal or degraded land that can provide increased regional agricultural income without utilizing land used for food production. (218) Moreover, cellulosic feedstocks require less pesticides and fertilizer than corn-based ethanol. (219) However, demand for cellulosic ethanol could result in adverse impacts on forests if they were cut to produce fuel or converted to plantations of fast growing trees. Other environmental concerns include the potential for soil erosion, soil quality degradation, loss of wildlife habitat, the introduction of non-native plant species, and nutrient releases to water bodies. (220) For example, if corn stover is used for fuel, the benefits of using this material for soil conditioning and erosion control is lost. As cellulosic biofuel production expands, other industries may be adversely affected. The paper industry, for example, is concerned that non-corn biofuel producers will compete for the raw material used to manufacturer paper. (221)
Using plant cellulose and extracting the sugars to make ethanol is more difficult than obtaining sugar from grains. (222) To convert cellulosic biomass to ethanol involves either a biochemical or a thermochemical process. The biochemical process involves pretreatment to release hemicellulosic sugars that are then turned into sugars using hydrolysis. (223) Usually the steam helps break apart the glucose molecule. (224) This is followed by enzymatic hydrolysis, which uses enzymes to break cellulose chains down to fermentable sugar. The sugars are fermented into ethanol and the lignin is recovered and used to provide the heat energy needed for the process. (225) Thus, cellulosic ethanol could be produced using less nonrenewable energy than corn-based ethanol. (226)
The thermochemical process uses heat and chemicals to produce syngas, which is carbon monoxide and hydrogen. The syngas is mixed with a catalyst and reformed into ethanol and other liquid coproducts. (227) Then the lignin is separated from the mixture, which may be burned for power production. At this point the sugar is treated in the same way as corn-based alcohol production. Yeast is added and allowed to ferment. Then the alcohol is separated from the fermented mash, and a by-product called "stillage" is left. The ethanol is dehydrated to produce fuel-grade ethanol. (228)
On July 7, 2011, the Department of Energy announced a $105 million loan guarantee for the development of a commercial-scale cellulosic ethanol plant called Liberty in Emmetsberg, Iowa. It will utilize 770 tons per day of corn cobs, leaves, and husks to produce 25 million gallons of ethanol a year. (229) The plant, a joint venture by POET of Sioux Falls, South Dakota and Royal DSM, a Dutch company, will use the enzymatic hydrolysis process. (230) This process was first used on a commercial scale in the Beta Renewables plant in Crescentino, Italy that opened in 2013. The Iowa plant opened on September 3, 2014, and a similar plant built by the same company opened in Brazil on the same date. (231) To make the enzymes used in biofuels, the Danish company Novozymes obtained $28.4 million through the American Recovery and Reinvestment Act to build a $200 million plant in Blair, Nebraska. (232)
The most important legal issue concerning the use of cellulosic ethanol is that its production has not matched the requirements mandating its use. In 2012, there was no commercial scale production in the United States, but EPA continued to mandate its use by refiners. (233) Because the amount of cellulosic ethanol required substantially exceeded the amount produced, the D.C. Circuit vacated the 2012 blending requirements, but upheld EPA's requirements for advanced biofuels because the volume required could come from sugarcane ethanol imports and biodiesel production. (234) For 2013, EPA regulations called for 810.185 gallons of cellulosic ethanol to be blended, which is well below the statutory 1.0 billion gallons. (235) EPA's 2014 proposed rule called for 17 million ethanol-equivalent gallons of cellulosic biofuel, but, as previously discussed, EPA has had serious problems in finalizing the rule. (236) EPA is also attempting to expand the amount of cellulosic renewable fuel by approving new fuels as qualifying for RFS credit. In 2014 EPA reclassified millions of gallons of advanced biofuel as "cellulosic ethanol," including compressed and liquefied natural gas from landfills and wastewater treatment plants. (237) This increased the amount of cellulosic ethanol to over 18 million gallons by late 2014. (238) But scaling up cellulosic ethanol production from nearly zero to 16 billion gallons in a decade is nearly impossible. In the first few years of the cellulosic mandate, many business had severe financial problems, and many failed. (239)
EPA's hope for expanded cellulosic ethanol use is based on new commercial-scale cellulosic ethanol plants that came online in 2013 with a combined capacity of nearly 88 million gallons per year, (240) though they are not likely to produce at that level. (241) The INEOS Bio Indian River BioEnergy Center in Florida, with an 8 million gallon per year capacity, and the KiOR facility in Mississippi, with an 11 million gallon per year capacity, are the first commercial-scale facilities to be registered as renewable fuel producers by EPA. (242) The KiOR operation uses a new technology that turns woodchips into a drop-in fuel that can be used without modification of the vehicle. The challenge will be to do so profitably. (243) Other plants include the Alpena Biorefinery in Alpena, Michigan; Fiberight LLC in Blairstown, Iowa; Fulcrum Bioenergy in Reno, Nevada; and POET/DSM in Emmetsburg, Iowa. Abengoa Bioenergy plans to begin production of 25 million gallons a year of cellulosic biofuel made from corn stover and switch grass at its Hugoton, Kansas plant in October 2014. (244) Another plant under development is a 30-million gallon per day DuPont facility in Nevada, Iowa. (245)
Biomass-based diesel is defined as renewable fuel that has lifecycle GHG emissions 50 percent or less than petroleum-based diesel. (246) Agri-biodiesel is defined at IRC section 40A(d)(2) as biodiesel derived solely from virgin oils, including esters derived from virgin vegetable oils from corn, soybeans, sunflower seeds, cottonseed, canola, crambe, rapeseeds, safflower...
Biofuel and advanced biofuel.
|Author:||Reitze, Arnold W., Jr.|
|Position:||Continuation of IV. Advanced Biofuels through VII. Conclusion, with footnotes, p. 338-365|
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