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Fuels Of The Future

Chemistry and agriculture join to make a new generation of renewable fuels

by Marc S. Reisch
November 20, 2006 | A version of this story appeared in Volume 84, Issue 47

Biorefinery Pilots
Credit: UOP
Allyn Pinnello and Veronica Godfrey test new biofuel processes at a UOP facility in Des Plaines, Ill.
Credit: UOP
Allyn Pinnello and Veronica Godfrey test new biofuel processes at a UOP facility in Des Plaines, Ill.

Biofuels were barely a factor in the energy market in the days of $1.00-per-gal gasoline. But as oil prices have risen, fuels derived from renewable sources such as corn, soybeans, and other crops have garnered a great deal of attention. Add concerns over energy security and longer term worries over dwindling hydrocarbon resources, and biofuels start to look attractive.

Experts say biofuels won't replace all petroleum-derived gasoline or diesel. Instead, biofuels such as biodiesel, ethanol, and biobutanol will extend fossil fuel supplies. From being a curiosity in the U.S., biofuels have become a national obsession. In his State of the Union address in January, President George W. Bush set a goal for the country to replace more than 75% of oil imports from the Middle East by 2025, largely through the use of biofuels.

Since then, the Department of Energy has taken the effort to develop biofuels a step further. At a speech before the Chamber of Commerce last month, DOE Secretary Samuel W. Bodman said his agency's goal is to first make cellulose-based ethanol a cost-effective alternative to gasoline by 2012, and then to displace 30% of current gasoline consumption with biofuels by 2030. Biofuels now account for 4% of U.S. gasoline consumption. What that means, Bodman said, is the U.S. must raise annual production of bioethanol from 5 billion gal currently to 60 billion gal within 25 years.

The fuss over renewable fuels has created a commercial frenzy. To meet these ambitious goals, chemical engineers will have to design many more than the 106 ethanol plants operating in the U.S. According to the Renewable Fuels Association, 48 new ethanol plants and eight expansions of existing plants are now under construction.

Eventually, most ethanol plants will have to run on nonedible, cellulosic feedstocks, rather than the corn that fuels them today. The U.S. cannot produce nearly enough corn to supply food needs and still meet ethanol targets. To operate under this more complex and as yet unproven technology, plants will come to depend on many new enzymes, microbes, catalysts, and chemical process aids.

Add biodiesel to the overall goal of reducing vehicle reliance on petroleum, and the need for design and process improvements grows. The U.S. currently has 86 biodiesel plants with a production capacity of 580 million gal per year. According to the National Biodiesel Board, producers plan to add another 820 million gal of capacity within the next 16 months.

Among the companies identified with traditional petroleum-derived chemistry, DuPont is notable for extending its interest in renewable chemical feedstocks to an active role in the development of biofuels technology.

Some years back, DuPont and sugar producer Tate & Lyle developed a p rocess to manufacture 1,3-propanediol, a feedstock for the polyester polytrimethylene terephthalate, from corn sugar. That venture led DuPont to think about how it could apply its fermentation know-how to making fuels and chemical feedstocks in a biorefinery, says David L. Anton, venture manager for DuPont's seven-month-old biofuels business unit.

In 2002, DuPont and several research partners received an $18 million grant from DOE to develop a refinery that would produce ethanol, as well as propanediol and other chemical feedstocks. Unlike the project with Tate & Lyle, which uses cornstarch alone, DuPont and these partners are looking to convert both cornstarch and corn cellulose into usable carbohydrates. The corn cellulose, known as stover, comes from the leaves and stalk of the corn plant.

DuPont has worked with DOE project partner Diversa to develop enzymes that break down the cellulose into sugars. And it has worked with DOE's National Renewable Energy Laboratory (NREL) to develop a fermentation organism, Zymomonas mobilis, that can produce ethanol both from the glucose that comes from starch and from the difficult-to-ferment xylose that comes from cellulose.

An outgrowth of the DOE project, Anton says, is a joint-venture agreement with ethanol producer Broin, formed in early October, to apply what DuPont has learned and to convert an existing Broin ethanol plant into a biorefinery at a cost of $220 million. The upgraded facility would operate on both corn and stover instead of on corn alone.

"As we learned more about ethanol," DuPont's Anton says, "we talked to fuel sellers and realized there were opportunities beyond ethanol to develop something more like a typical fuel molecule." The result was a partnership formed in June between DuPont and oil giant BP to make butanol from biomass. Although ethanol and butanol are both alcohols, butanol has a higher energy content, can be more easily blended with gasoline, and can blend at higher concentrations without retrofitting cars, Anton notes.

Just as DuPont worked with Tate & Lyle to accomplish the conversion of corn sugar to propanediol, BP and DuPont now plan to work with British Sugar to convert an ethanol fermentation facility to make butanol, Anton says. The partners will work to develop a biological catalyst to ferment biomass-derived sugar to butanol.

BP and DuPont are confident of success: They say they will introduce biobutanol-containing gasoline in 2007 on a limited basis in the U.K. By 2010, they say, improved biomass conversion technology will allow broader commercialization.

Corn Mash
Credit: DuPont
Scientist Max Li develops biofuels at DuPont's Experimental Station, Wilmington, Del.
Credit: DuPont
Scientist Max Li develops biofuels at DuPont's Experimental Station, Wilmington, Del.

DuPont and BP are not the only firms working on new biofuel technologies. Another traditional oil company, Chevron, has launched three biofuel research partnerships this year. The most recent one matches Chevron with NREL to convert biomass such as forestry and agricultural waste into ethanol and renewable fuel.

Also pursuing second-generation biofuels, Spain-based Abengoa has teamed up with enzyme specialist Dyadic International to develop an enzyme derived from a fungus, Chrysosporium lucknowense, that can cost-effectively make ethanol from biomass. Under the deal, Abengoa is investing $10 million in Dyadic stock.

Meanwhile, VeraSun, the second largest U.S. ethanol maker, has developed a process to make both ethanol and biodiesel from the same feedstock. The company says it has applied for a patent for the process, in which it can extract oil from distillers grains, a coproduct of corn ethanol production, and then make biodiesel from the oil. VeraSun plans to build a 30 million-gal-per-year biodiesel plant by 2008 at an as-yet-undetermined site. It has hired engineering firm Lurgi PSI to design and engineer the new plant.

While companies like VeraSun, DuPont, and Broin are pursuing biofuels themselves, other firms want to capitalize on the need for ancillary technology services. Two traditional refining catalyst and system suppliers, Honeywell's UOP unit and the Davison division of W.R. Grace, formed units within a month of each other to supply such things as catalysts and adsorbents to petroleum refining and biorefinery customers.

Jennifer Holmgren, director of UOP's renewable energy and chemical unit, says her firm has developed a number of bioprocesses with petroleum refiners in mind, but the firm is in contact with agricultural product customers as well. Either way, "we are good at processing hydrocarbons," she says.

Beginning in 2004, UOP, one of the world's top three catalyst makers, began partnering with NREL and Pacific Northwest National Laboratory to learn how to process renewable feedstocks. With PNNL, for example, UOP came up with catalysts that convert glycerin to propylene glycol, Holmgren says. The technology could provide a new outlet for the excess amounts of glycerin that are being created in the conversion of oils and fats to biodiesel, she points out.

Another new UOP technology converts vegetable oils and greases into a diesel fuel that is more energy-dense and has a higher cetane number than either petroleum-derived diesel or biodiesel. Conventional biodiesel is typically made by catalytically combining vegetable oil and methanol, but the substitution of hydrogen for methanol produces a higher performance hydrocarbon fuel, Holmgren says.

UOP has also done work to blend vegetable oil and naphtha with the right catalysts to create high-quality olefins, she says. But the firm is only beginning its work to develop the thermo- and biochemical processes needed to commercialize a fuel and chemicals biorefinery. Holmgren adds that the company could partner with an enzymes specialist to develop biorefinery processes.

Grace's Davison division started a group within its R&D unit a year ago to apply its material science to biofuels development, says Gregory E. Poling, president of the division. "A number of refining customers are looking at biofuels," Poling says, and Grace wants to supply them with products such as enzyme carriers, molecular sieves for fuel purification, and chromatography-based analytical and quality-control tools.

According to Robert H. Harding, Grace's director of incubator technology, the firm is also working on ways to convert by-products from corn ethanol production into chemical precursors.

Even suppliers of process plant fluids are trying to win a piece of the burgeoning biofuels pie. For instance, Solutia is working to get its hydrocarbon-based Therminol heat-transfer fluids specified for use in biodiesel reactors and associated postreactor purification. "We are working with engineering firms to combine their biodiesel production know-how with our knowledge of heat-transfer fluids," says Ravi Prakash, an engineering specialist with Solutia.

Because of the efforts of Solutia, UOP, Grace, and others, biomass-based fuels are unlikely to remain the drop in the bucket that they are today. How much of the fuel bucket they will fill tomorrow will depend on technologies that many firms are just now starting to explore.

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