Biofuels

By Gary Digiuseppe

A “biofuel” is one that is produced from substances derived from a living thing. These encompass a range of fuels either in development or on the market; they include ethanol and other alcohol fuels, biodiesel, biogas, solid combustibles like wood, and a host of secondary fuels, which are produced when the feedstock for the fuel (“biomass”) first passes through a transitory phase.

In most cases, fewer toxic emissions are produced from the combustion of biofuels than from the conventional fuels they replace. The fuels also come from renewable sources, so the use of a gallon of biofuel means the conservation of one more gallon of fuel from a finite resource like oil and gas reserves. And because many of those reserves are overseas, the use of domestically produced biofuels offers more benefits to the local economy.

Ethanol is the most heavily used biofuel in the United States. According to a trade group, the Renewable Fuels Association (RFA), US ethanol production capacity had reached 7.23 billion gallons a year as of the end of 2007, with another 6.22 billion gallons under construction. The US Department of Agriculture estimates US ethanol production was 5.9 billion gallons for the 12 months ending September 30, 2007, and projects production in the 2007-08 marketing year will be 9.3 billion gallons; that would be well over 6% of the entire US motor fuel supply. Ethanol is typically blended with gasoline at a 10% ratio, known as E10; California uses a 5.7% blend, which ensures the fuel carries 2% oxygen by weight. Nearly half of all gasoline sold in the US contains ethanol.

Gasoline-powered vehicles in the United States rarely run on pure ethanol; the highest available blend is 85% ethanol and 15% gasoline, and is called E85. Compression-powered or diesel engines can run on E95 or greater; in Brazil, which sought to become energy independent in the 1970’s and mandates 23% ethanol blends, some vehicles run on E100 with a few percentage points of water added. So-called “flexible-fuel” vehicles can be easily shifted to run on any blend from pure gasoline to E85; more than 1,300 fueling stations now offer E85, more than 700 of them in the Upper Midwest, which also produces the bulk of the nation’s ethanol supply. The Energy Policy Act of 2005 offers tax credits of up to $30,000 for businesses and $1,000 for homeowners who install new E85 pumps.

Although there are numerous kits on the market for converting conventional vehicles to flexible fuels, only one has been approved by the Environmental Protection Administration , which has tested and certified its effect on emissions; use of the others may be illegal. The “Flex-Box Smart Kit” is designed for larger vehicles using a Ford 4.6-liter engine, such as the Ford Crown Victoria, Mercury Grand Marquis, and Lincoln Town Car. The manufacturer, Chicago-based Flex Fuel US, hopes to get EPA approval for kits suitable for other makes and models of passenger vehicles, light trucks, and performance vehicles by fall of 2008.

Flex Fuel US says its device works by monitoring the vehicle’s engines and adjusting fuel injection accordingly; higher blends of ethanol to gasoline require higher rates of injection to maintain an optimal fuel/air mixture. Once the “Smart Kit” is installed, the vehicle can run on any blend of fuels from E85 to pure gasoline. The kit costs $1,295; for an additional $200, you can buy it from and have it installed by one of the nation’s 720 AAMCO Transmission Centers, as part of the mechanic chain’s “Eco-Green Auto Service” line.

There are about six million flex-fuel vehicles on the road, and the automobile industry is building approximately one million new ones a year. Daimler-Chrysler alone plans to build 500,000 flex-fuel vehicles for the 2008 model year; the makes and models available include the Chrysler Aspen and Sebring, the Dodge Avenger, Dakota, Durango, Grand Caravan and Ram Pickup, the Jeep Grand Cherokee and Commander, and the Town and Country. Flex-fuel vehicles made by Ford include the Crown Victoria, the Escape Hybrid and Hybrid Electric, the F-150 and F-150 LPI, the Grand Marquis, the Lincoln Town Car and the Mercury Mariner-Hybrid Electric. GM offers flex-fuel in the Chevy Avalanche, Express, Impala, Malibu, Silverado, Suburban, Tahoe and Tahoe Hybrid Electric, and the Uplander, and in GMC Savanas, Sierras and Yukons and Saturn Aura and VUE Green Line Hybrid Electric models. There are also Flex Fuel versions of popular vehicles sold by Honda, Mazda, Mercedes-Benz, Nissan and Toyota. The web site of the National Ethanol Vehicle Coalition, e85fuel.com , has a list of all past model year vehicles that included flex-fuel versions, as well as a searchable database of E85 fueling stations.

Consumers can receive federal and state incentives for purchasing alternative fuel vehicles. Under the Energy Policy Act of 2005, the tax credit is equal to 50% of the incremental cost of the vehicle, up to a maximum of a $2,500 credit for vehicles weighing less than 8,500 lbs. Most flex-fuel vehicles do not cost more than, or are priced the same as, their conventional alternatives.

Most major car manufacturers say the use of E10 will not void their warranties; so do makers of power equipment, motorcycles, snowmobiles, outboard motors and lawnmowers. However, ethanol blends are not recommended in small aircraft. Ethanol is known to be corrosive to a number of substances, including soft metals like aluminum, zinc and brass, natural rubber, polyurethane and some other synthetic plastics. E85 must be stored in fiberglass and steel tanks certified for ethanol by UL or by the manufacturer. Ethanol is also extremely hydroscopic and will absorb water; for that reason, it’s not currently feasible to transport it via pipeline.

In the United States, almost all commercial ethanol is made from corn; in Brazil, which is the world’s leading ethanol producer–although the US will probably surpass Brazil in the next year–processors use cane sugar. The key to the production of ethanol is the use of carbohydrates as feedstocks; field corn is 75% carbohydrates and is the most abundant crop in the US, with a 2007 harvest of about 334 million metric tonnes. The USDA expects nearly a quarter of that, 81 million tonnes, to be used in ethanol production in the 2007-08 marketing year. After the ethanol is produced, the remaining 25% of the corn kernel is high in protein and oil, and is diverted into livestock feed. Early critics of the US ethanol program claimed it took more energy to produce ethanol–between the planting and harvesting of corn, the haul to the processor, refining and the subsequent distribution–than the ethanol itself contained. Those estimates failed to take into account the remaining feedstuff. The US Department of Agriculture says the production of ethanol yields 1.67 units of energy for every unit expended. According to the RFS, the “seed-to-wheel” reduction of greenhouse gases in the combustion of corn ethanol versus gasoline is 29%; that includes the emissions produced by farmers in growing the corn.

Since the 1978 Persian Gulf Oil Crisis, ethanol-blends have enjoyed a partial exemption from gasoline’s federal excise tax; the exemption is now 51 cents a gallon. Some Midwestern states, in hopes of attracting processing plants, also adopted ethanol subsidies. The 2005 Energy Policy Act included a Renewable Fuels Standard, which requires the nation’s fuel refiners to use a minimum level of biofuels. The RFS was 4.7 billion gallons in 2007, and is slated to reach 7.5 billion gallons in 2012. In addition, states have adopted their own mandates; Minnesota was the first to require all gasoline sold in the state to carry 10% ethanol. A new state law will double the requirement to 20% by 2013, unless ethanol already represents 20% of the state’s motor fuels by 2010, and provided the federal government gives Minnesota permission to use E20 gasoline. Hawaii now also has an E10 requirement, and Missouri’s takes effect on January 1, 2008. Several other states have adopted mandates for the future, most of them contingent upon the state reaching a specific level of ethanol production within its borders.

There have also been environmental mandates. Under amendments to the federal Clean Air Act that were adopted in 1990, the Environmental Protection Agency required the use of oxygenated fuels dubbed “reformulated gasoline” in “nonattainment” metropolitan areas with unacceptable levels of smog, and allowed their use to reduce carbon monoxide emissions in some parts of the country during winter months. Ethanol is 35% oxygen by weight; its presence in gasoline reduces CO emissions by up to 25%. Ethanol’s chief competitor as an oxygenate was methyl tertiary butyl ether (MTBE), which is derived from natural gas and was therefore preferred by energy companies with both oil and gas holdings. But early in this decade, studies revealed MTBE, a known carcinogen, had contaminated hundreds of California groundwater sites, and then-Gov. Gray Davis ordered its use phased out. Other states followed California’s lead, and ethanol became the lone remaining oxygenate on the market.

However, there are environmental tradeoffs. Although ethanol burns “cleaner”, thereby reducing its greenhouse gas emissions, it’s more volatile than gasoline. Ethanol produces lower emissions of volatile organic compounds (VOC’s) at the tailpipe than does gasoline, but adding it to gasoline raises the vapor pressure, and increases VOC’s. To compensate, the EPA had required gas sold in smog nonattainment areas to be lower in octane. The oxygenate mandate in ozone nonattainment cities was eliminated with the 2005 Energy Policy Act.

Many believe the “fuel of the future” to be cellulosic ethanol. It’s the same end product, ethyl alcohol (C2H5OH), but instead of being produced from the fructose in grain or sucrose in sugar, it’s derived from glucose and xylose, the six-and-five carbon sugars trapped in plant materials like stems, leaves and branches. The lignocellulose within those structures is broken down with enzymes, and the sugars fermented into alcohol. Although these methods are not yet commercially viable, several processors plan to build pilot cellulosic ethanol plants in the United States and Canada.

Where an acre of corn only produces enough ethanol to replace 33 gallons of gasoline, the energy in an acre of cellulosic biomass could potentially replace 860 gallons of gas. And unlike corn, an annual crop that needs to be sown, nurtured and harvested every year, a native prairie grass called switchgrass is a perennial and generates up to 15 tonnes/acre a year with little or no farm inputs.

A study produced by the Departments of Agriculture and Energy identified 1.3 billion tons of feedstocks in North America that could be converted into 100 billion gallons of ethanol; this would be the equivalent energy of more than 40% of the gasoline consumed annually in the United States. It should be pointed out that ethanol does not replace gasoline on a 1:1 basis. According to the Department of Energy’s Oak Ridge National Laboratory, ethanol only contains 75,700 British Thermal Units (Btu) to the gallon; gasoline is 115,000 Btu, and motorists tend to get slightly lower mileage on low ethanol blends. However, pure ethanol has an octane rating of 113, versus 87 for regular gasoline, and adding it to gas can reduce pre-ignition or engine knock, as well as act as a natural antifreeze.

Biofuels have benefited from environmental restrictions imposed on other fuels. For instance, the phase-out of leaded gasoline in the 1980’s created an opening for ethanol as an octane enhancer. Similarly, the EPA’s new strict rules on sulfur in diesel fuel have enhanced the market for biodiesel as a lubricant additive to diesel fuel. Although diesel engines can run on as much as 100% biodiesel (B100), B2 or B5 blends are more common in the marketplace.

A process called transesterification is used to convert vegetable oils and animal fats into biodiesel; 10% of the feedstock is left over as glycerine. In the United States, biodiesel is most often made from soybean oil or animal fats; it can also be produced, with additional purification steps, from refuse such as kitchen grease, and other countries use feedstocks like palm oil or canola oil.

The biodiesel industry got its start through a 1998 law that reimbursed processors for the cost of the feedstock; it remained in an experimental stage, producing relatively small quantities for tests in metro transit fleets and school buses, until 2004, when Congress passed a $1/gallon excise tax credit. Production grew rapidly for the next several years, jumping from only about two million gallons in 2000 to an estimated 220 million gallons in 2007. Worldwide, the largest producer of biodiesel is the European Union, where a high percentage of passenger cars run on diesel; Germany alone produced 690 million gallons of biodiesel in 2006.

According to the Jefferson City, Mo. based National Biodiesel Board (NBB), Biodiesel offers numerous environmental advantages relative to conventional petroleum-based diesel. Emissions of sulfates and sulfur oxide, which are among the leading causes of acid rain, are virtually eliminated; emissions of hydrocarbons, which form smog and ozone, are 67% lower for B100 than for convention diesel, 12% lower for a B20 blend. Carbon monoxide emissions for B100 are 48% lower, and emissions of polycyclic aromatic hydrocarbons and nitrated polycyclic aromatic hydrocarbons, depending upon the compound, range from 50% lower to upwards of 99% lower. Particulate matter emissions are 47% lower. Nitrogen oxide (NOx) emissions, though, can be as much as 10% higher from pure biodiesel, although the NBB says the lack of sulfur in the fuel allows the use of NOx inhibitors that can’t be used in convention diesel.

B20 will cloud (form wax crystals), plug filters and cease to flow at temperatures 2-10°F. higher than conventional diesel; the fuel will gel faster than will petroleum diesel in cold weather. Biodiesel can also harm some natural rubber or butyl rubber-based engine components, chiefly fuel pump seals and fuel hoses, on older vehicles; these are typically found in cars built before 1993, and should be replaced if the vehicle will run on blends above B20. The NBB has established an accreditation panel that audits biodiesel producers to ensure their products and processes meet ASTM quality standards; their products carry a “Certified Biodiesel Marketer” seal. Processors can also become accredited under the BQ-9000 program.

Biodiesel is an excellent solvent–if you spill it on a painted surface and fail to remove it, it will dissolve the paint. For that reason, it can contribute to fuel filter clogging in vehicles previously powered by conventional diesel; the petroleum diesel will leave sediment in the bottoms of fuel lines, tanks and delivery systems, and the biodiesel dissolves it. So, when initially moving to a biodiesel blend, filters may need to be changed more often. However, biodiesel usually has a higher cetane rating than conventional diesel, and demonstrates similar fuel consumption, horsepower, torque, and haulage rates.

There are other benefits related to human health and safety. The flash point of biodiesel, the temperature at which it ignites, is over 200°F, compared to 125°F peroleum diesel. Biodiesel is largely non-toxic–a fatal dose for a 160-lb person would be about a quart and a half. And it degrades in the environment four times faster than conventional diesel. The NBB says for every unit of energy needed to produce biodiesel, 3.24 units are gained–the most efficient production of any fuel.

Most engine manufacturers say use of up to B20 blends will not void their warranties. However, the Engine Manufacturers’ Association warns raw or refined vegetable oils and animal fats experience significant degradation due to oxidation compared with petroleum diesel fuels, and their use as fuels can lead to the formation of sludge in the storage or vehicle fuel tank, which in turn, can plug fuel filters. “Straight,” non-transesterified vegetable oil can be used in older diesel engines with indirect injection systems, but the US Department of Energy says the oil can have significant adverse effects in diesel engines and should not be used.

New technologies are coming forward that could dramatically redefine the traditional image of a biofuel. Thermal depolymerization, or TDP, mimics the way nature produces petroleum by subjecting organic matter to intense heat and pressure. The nation’s largest meat and poultry processor, Tyson Foods of Springdale, Ark, has formed a partnership with ConocoPhillips to convert chicken fat from Tyson’s plants into TDP, which in turn will be made into diesel at one of ConocoPhillips’ existing facilities.

Tyson has also entered into an agreement with Syntroleum Corporation of Tulsa, Okla to build a plant that will produce 75 million gallons of diesel from synthetic oil using the Fischer-Tropsch process. Fischer-Tropsch was invented by two German scientists in the 1920’s, and uses a chemical catalyst to turn carbon monoxide and hydrogen into liquid fuels; fuelmakers convert matter containing carbon and hydrogen by subjecting it to high temperatures in the presence of oxygen, a process called gasification. Although Fischer-Tropsch typically uses coal or natural gas as a feedstock, the companies’ venture, Dynamic Fuels LLC, will utilize fats and grease supplied by Tyson. Fischer-Tropsch can also be employed to convert the waste from pulp and paper mills; a Finnish forest products company, UPM, intends to use the process to make fuels from the leftovers at its plants.

The future of biofuels in America appears quite bright; production has gone from virtually nothing 30 years ago to over six billion gallons a year today, and industry and government are uniting to find new ways to deliver alternative fuels to the marketplace. And, in coming years, the story may become yet more dramatic. The catalyst for industry growth has been higher costs of competing energies; if crude oil prices fade, interest from the government and the private sector may wane. But, for now, record petroleum prices are fueling even more zeal to develop alternative sources of liquid fuel.