"Children of the Corn," Feature Article, January 2003

FEATURE FOCUS: Alternative Power Systems

children of the corn

A growing contingent is at work to light a fire under ethanol.

by Gayle Ehrenman, Associate Editor

Other renewable power sources, mainly wind, sun, and water, may be drawing the lion's share of attention, but ethanol is a renewable fuel that's already well-entrenched and poised to spread into new arenas.

Early in the automobile era, ethanol actually had a chance of becoming the primary fuel instead of the alternative. Henry Ford intended his Model T to run on pure ethanol, but less expensive gasoline soon emerged as the dominant fuel.

The majority of ethanol in use today is employed as a gasoline blending agent, in a mix known as E10 (for the 10 percent ethanol mixed into the gasoline). More than one billion gallons of ethanol are blended with gasoline every year in the United States, and every automobile on the road today is capable of running on E10.

In all, E10 accounts for 10 percent of all gasoline sold in the United States. Its major advantages are that the ethanol fraction, derived from corn or other biomass, is reliable and renewable, and it is clean burning, composed of carbon, hydrogen, and oxygen.

The Illinois Department of Commerce and Consumer Affairs has run a John Deere combine for 800 hours on No. 2 diesel blended with 10 percent ethanol, with no ill effects on its mechanical operation.

Ethanol is set to grab an even greater percentage of the gasoline blending market, due to the banning of the most commonly used gasoline additive, methyl tertiary butyl ether, in California, New York, and a dozen other states as of January 2004. That leaves ethanol as the only viable oxygenating agent, to raise octane and reduce emissions.

There are some developments under way for ethanol that may help it move beyond the gasoline blend business. Researchers are looking at the use of ethanol to power fuel cells, or to blend with diesel, to form the less-polluting e-diesel. New methods for converting other biomass feedstocks, such as switchgrass and wood chips, into ethanol are expected to lower the overall cost of production significantly. Most ethanol available for fuel today is derived from corn starch.

Commercial e-diesel, ethanol-powered fuel cells, and cheaper production are still some ways off. E-diesel, the closest of these technologies to marketability, has yet to receive all the EPA approvals required for a commercial fuel. It has some major safety issues to overcome and is at least two years away from commercial use, said Norm Marek, manager for Alternate Energy and Transportation Fuel Programs in the Illinois Department of Commerce and Consumer Affairs, or DCCA, in Springfield.

For fuel cells and ethanol production technologies, the timeline runs even further. Stationary fuel cells powered by ethanol are roughly five years away, according to Gary Welch, the technical support manager for Williams Bio-Energy in Pekin, Ill. Waste biomass-to-ethanol conversion isn't expected to reach large-scale production levels until 2010, according to John Sheehan, a senior research engineer at the National Renewable Energy Laboratory in Golden, Colo.

From Corn to Cars

Ethanol, referred to chemically as either C₂H₆O or C₂H₅OH, is produced through one of two related fermentation processes, known as wet and dry milling. Each process involves the use of enzymes to convert starch, which is present in high concentrations in corn and other grains, into sugars. Yeast is then added to ferment the sugars. During this fermentation, the yeast converts the sugar into ethanol and carbon dioxide. The non-fermentable part of the corn is processed to make a variety of products.

Wet milling, which involves soaking the corn before
it's converted, produces a greater number of valuable byproducts, but yields less ethanol per batch. Dry milling, which involves grinding the entire corn kernel into flour, produces more ethanol per batch, but yields lower-value byproducts.

Both of these processes require heat that is derived from electricity.

Before it leaves the plant, ethanol is blended with about 5 percent denaturant (typically, natural gasoline) to render it undrinkable, and thereby exempt from beverage alcohol taxes.

One of the criticisms of ethanol has traditionally been that making it consumes more energy than it produces. A recent study by the U.S. Department of Agriculture, however, concludes that "ethanol production is energy efficient because it yields 34 percent more energy than issued in growing and harvesting the corn and distilling it into ethanol."

However, ethanol doesn't offer the fuel efficiency of gasoline. A gallon of ethanol contains 28 percent less energy than a gallon of gasoline. This has been one of the drawbacks to flexible fuel vehicles that run on higher blends of ethanol, such as E85.

The national Ethanol Vehicle Coalition estimates that there are currently more than two million flexible fuel vehicles, or FFVs, on the road, but most drivers aren't even aware that they can fuel their vehicles with anything besides standard gasoline. All 2003 Ford Taurus models, as well as DaimlerChrysler's Dodge Caravan and Chrysler Town & Country minivans, among others, can run straight from the factory on E85, standard gasoline, or a mix of the two. Onboard sensors monitor the fuel mixture and the onboard computer adjusts spark timing and fuel flow to optimize performance.

Ethanol, an alcohol fuel that is in use primarily as a gasoline blending agent, is currently derived by fermenting the starch in corn kernels.

Flexible fuel vehicle adoption has been slowed by the lack of public fueling sites. Currently, there are only about 200 public E85 fueling stations, most of which are in the Corn Belt. This lack of infrastructure has meant that most people who drive flexible fuel vehicles will never fill them with E85. For that reason, most of the FFVs promoted as such are being sold as fleet vehicles into cities where there is a legislated requirement to put alternate fuel vehicles into service.

On the positive side, ethanol burns cleaner than conventional fuels, which results in fewer tailpipe emissions. A car burning E10 emits as much as 30 percent less carbon monoxide than one running on conventional gasoline; 12 percent fewer volatile compounds; 30 percent fewer toxic components, such as benzene and toluene; and 3 percent fewer nitrogen oxides.

There is one irony to all this: Ethanol is too costly to use in the production of ethanol. At this point, most ethanol production consumes electricity generated by coal, which produces high levels of NO_x and sulfur dioxide emissions.

Cleaner, Cheaper Fuel

One major research effort at the National Renewable Energy Laboratory is seeking to address both the cost issue and need for coal in the production of ethanol. The Bioethanol Pilot Plant, a test plant funded by the Department of Energy, is using everything from waste newsprint to rice straw, switchgrass, and corn stover to produce ethanol.

The waste biomass-to-ethanol process relies on a new class of enzymes that serve as catalysts to convert cellulose and hemicellulose—the parts of biomass that currently are considered waste—into the sugars that are then fermented into ethanol, according to NREL's Sheehan. The enzymes required to make this process commercially viable are expected to be delivered next year by Genencor of Palo Alto, Calif. What's left after the cellulose and hemicellulose are processed is lignin, a polymer that can be burned to produce steam and electricity to power an ethanol production plant.

The main focus of the project at this point is processing corn stover—every part of the corn plant except the kernel—that is currently considered waste. The goal is to have a commercial demonstration of the corn stover-to-ethanol project online by 2007.

Sheehan estimates that it's possible to produce 10 billion to 20 billion gallons of ethanol per year from this material, a major increase over the two million gallons per year produced from corn kernels alone.

NREL and industry researchers are using NREL's Alternative Fuels Users Facility to move advances in ethanol and biomass research into development phase.

The Illinois Department of Commerce and Consumer Affairs, meanwhile, has partnered with NREL; John Deere in Moline; the National Corn Growers Association in Chesterfield, Mo.; and the Renewable Fuels Association in Washington, to extensively test and quantify the potential of e-diesel in off-road, diesel-powered equipment.

E-diesel is a blend of 10 to 15 percent ethanol mixed with at least 80 percent No. 2 diesel fuel and up to 5 percent of an additive to keep the two fuels blended. It has been found to reduce particulate matter and carbon monoxide emissions, but has little effect, positive or negative, on NO_x emissions, according to Wendy Clark, NREL's group manager for fuels performance.

In light of the increased restrictions placed on diesel fuel by the Environmental Protection Agency, e-diesel has some real appeal for heavy-vehicle manufacturers, such as John Deere. The DCCA is conducting a series of laboratory engine emission, durability, and component compatibility and performance tests in three proprietary series of John Deere diesel engines, Marek said.

No modifications have been required to accommodate a 10 percent e-diesel blend. To date, one series of tests has run a John Deere combine for 800 hours on the 10 percent blend, with the mechanicals remaining within factory spec.

As with ethanol-blended gasoline, e-diesel suffers from poorer fuel economy than unblended diesel. A 10 percent blend will deliver 3 to 4 percent lower fuel economy than standard diesel, Marek said. While that is a negligible loss, heavy equipment will suffer a power dropoff when it burns e-diesel, he said.

Safety Woes

In addition, there are some major safety issues that make the fuel unlikely to become available on a retail basis, according to Bob McCormick, senior engineer for NREL. The biggest concern is flammability—something most diesel users rarely consider.

E-diesel has a low flashpoint, McCormick said, creating the very real concern that ethanol vapor in a vehicle's fuel tank will mix with air and be ignited by a spark during refueling or during a crash. DCCA is conducting tests with NREL to determine if installing a flame arrestor in the fill mouth of a vehicle's gas tank will help prevent the problem.

Marek predicts that this device, coupled with education and control of the fuel in a fleet-dispensing setting, will make e-diesel a viable fuel source for heavy equipment manufacturers, like Deere, in roughly two years. NREL's McCormick cautions that it is too early in the analysis of the problem to know whether other safety issues will crop up.

Fuel Cell Power

The concept of using ethanol to power fuel cells is even further away from commercialization, but seems more likely to have wide application. Williams Bio-Energy's Welch said that the company has partnered with Caterpillar in Peoria, Ill., Nuvera Fuel Cells in Cambridge, Mass., the Illinois DCCA, and the U.S. Department of Energy to develop and test an ethanol-fueled proton exchange membrane fuel cell system.

Anhydrous denatured ethanol will be used as the base fuel in the project, which will be based at Williams' Pekin, Ill., facility. The goal of the demonstration is to prove the durability of the stationary fuel cell by logging 4,000 hours of continuous operation. The system will produce 15 kW of electric power.

NREL researchers are developing technology to produce ethanol from the fibrous waste material (cellulose and hemicellulose) in the corn stalks and husks, which is collectively known as corn stover.

Nuvera is providing the fuel cell system and the reformer, which will use a hybrid of partial oxidation and autothermal reforming to convert the ethanol to the hydrogen required by the fuel cell, according to John Batal, Nuvera's program manager for the project. Ethanol is easy to reform and easier to store and transport than pure hydrogen, making it particularly suitable for use in fuel cells, he said.

Caterpillar will provide the power conversion equipment to convert the fuel cell's direct current to the alternating current required by Williams' local electric grid. Williams is providing the site, the ethanol, and the power grid.

Nuvera has been testing the fuel cell system and reformer since July and expects to deliver it to the field test site at the end of February, Batal said. If all goes well, the durability test should be completed six to eight months later.

There are only about 200 public E85 fueling stations in the United States, which is slowing adoption of flexible fuel vehicles.

Despite these innovations, ethanol has a long way to go before it is widely adopted as anything more than a gasoline additive. For starters, it still needs to be transported by truck or rail, a process that is too costly to be widely used outside of major corn producing areas. Current pipeline technology doesn't safeguard against water pockets diluting the ethanol during transport, NREL's Clark said. And, there is an elastomer compatibility concern with the seals in pipelines and pumping equipment that makes it unlikely that fuel ethanol will be delivered that way any time soon.

Perhaps more significantly, ethanol production is still quite expensive. The U.S. government provides subsidies to fuel blenders for adding up to 10 percent ethanol, but there are no tax credits or subsidies for a higher percentage of ethanol use.

In order for ethanol to become more widely used as a fuel, either the cost of production must be significantly reduced or a national standard, mandating the use of renewable fuels and providing incentives for their use, will have to be issued. Until that time, gasoline and other fossil fuels have little to fear from ethanol.