Beyond Cellulosic

While cellulosic technologies receive the most attention as related to scale-up of next-generation ethanol production, other technologies are also being developed to meet future advanced biofuel mandates.
By Erin Voegele | October 06, 2009
Research and development efforts to establish viable, economical, commercial-scale cellulosic ethanol technologies have been ongoing for decades and always seem to be five years away. Approaching advanced biofuel mandates as established in the Energy Independence and Security Act of 2007 has increased interest and investment in many of these technologies. And while many cellulosic ethanol companies have made recent breakthroughs and are on the verge of reaching commercial-scale production levels, a diverse range of advanced ethanol technologies is nearing or, in some cases, entering commercial-scale production as well.

In many cases, these alternative technologies have managed to circumvent several of the challenges that still face cellulosic ethanol production. Some of these companies have developed advanced biofuel technologies that effectively negate problems associated with high input costs, feedstock handling and logistics, and scale-up issues. In addition, many of these alternative processes are employable in areas that cannot easily support either traditional corn ethanol production or cellulosic production, including urban and desert areas.

Gasification and Syngas Conversion Technologies
While cellulosic technologies typically employ either an enzymatic or an acid hydrolysis process that requires pretreatment and a predominantly homogeneous feedstock, both Warrenville, Ill.-based Coskata Inc. and Montreal, Quebec-based Enerkem Inc. have developed gasification and syngas conversion technologies that are feedstock flexible and require no pretreatment. In addition, while both traditional and cellulosic ethanol technologies are only able to convert the sugar-based portion of any feedstock into fuel, Coskata and Enerkem's technologies are able to transform the entire feedstock into ethanol.

During the front-end gasification process employed by both technologies, carbon-rich feedstock is heated in a controlled environment with pressure and a little oxygen. Rather than causing combustion, the heating process results in a gaseous mixture of hydrogen and carbon monoxide known as synthesis gas (or syngas), which is similar to natural gas. The hydrogen and carbon monoxide molecules can then be reconfigured into a variety of end products, including ethanol. "It's sort of as if you would suspend the [feedstock] material and raise it to its gaseous state, halfway between a solid state and combustion," Enerkem CEO Vincent Chornet says.

Although both technologies utilize similar and well-established front-end gasification processes and can employ any carbon-rich feedstock, including post-recycled municipal solid waste (MSW), cardboard, wood chips, crop waste or glycerin, that's where the similarities between the two technologies end.

In Enerkem's process, feedstock is converted into syngas inside the company's proprietary gasification system. It is then cleaned. "We remove particulates and tar, and we also condition [the syngas] in terms of making sure we get it to the right hydrogen and carbon monoxide quantity," Chornet says. "The result is a clean, chemical-grade gas that is very similar to natural gas."

The hydrogen and carbon monoxide molecules contained in the syngas are then recombined into methanol using a copper-based metal catalyst. In the final step of the process, the methanol is used to build ethanol molecules.

Enerkem was formed in 2000 and established a pilot facility in 2003. The pilot facility has operated more than 3,500 hours and has been used to test Enerkem's technology using more than 20 different feedstocks.

In 2007, Enerkem commenced construction on a 1.3 MMgy commercial-scale facility in Westbury, Quebec. The facility is designed to utilize decommissioned electric poles as feedstock. To date, the Westbury facility has produced conditioned syngas. It is expected to begin alcohol (methanol/ethanol) production near the end of this year.

While Enerkem's production technology is feedstock flexible, Chornet says his company's primary focus is on post-recycled MSW because it is widely available and has a cost-negative nature.

According to Chornet, Enerkem currently has four additional projects in the pipeline that are expected to produce a combined 90 million gallons of ethanol annually, including a 10 MMgy facility in Edmonton, Alberta, that will utilize post-recycled MSW. "The [company's] next step is to build the Edmonton project," he says. "It is now fully permitted and we are looking for construction to begin by the end of the year." That facility is expected to be operational by mid-2011. Enerkem is also working to develop a 20 MMgy facility in Pontotoc, Miss., that is expected to utilize post-recycled MSW, wood residues, construction and demolition debris and treated wood.

While the front-end gasification process utilized by Coskata's syngas conversion technology is similar to Enerkem's, the back-end ethanol production process is markedly different. Instead of using a metal catalyst to drive conversion of hydrogen and carbon monoxide into fuel, Coskata uses a biological catalyst to ferment the syngas into ethanol.

"The core of Coskata technology is a set of anaerobic bacteria that breathe in syngas," says Wes Bolsen, Coskata's chief marketing officer and vice president of government affairs. Because the process creates only ethanol rather than a mixed stream of alcohols, Bolsen says the technology is able to realize high yields.

According to Bolsen, the anaerobic organisms employed by the technology are not genetically modified. "Our base-level organisms came out of the Oklahoma Biofuels Consortium, and we've spent the past three years really transforming them through mutations and selective breeding."

By using anaerobic organisms rather than a chemical catalyst, Bolsen says Coskata is able to ferment the syngas into ethanol using low temperatures and low pressure, which reduces the technology's energy consumption. "It's the simplicity of the process that really makes it one of the leading conversion technologies," he says.

Coskata was formed approximately three years ago and has since developed a pilot facility adjacent to its headquarters near Chicago. In addition, the company has established a semi-commercial facility near Pittsburgh and is in the process of developing a commercial-scale 55 MMgy facility in the Southeast that will utilize woody biomass to produce ethanol. Bolsen says the design and engineering of the facility is complete and a location has been selected. Construction is expected to begin as soon as financing is in place.

Photosynthetic Technology
While Coskata and Enerkem have developed feedstock-flexible production technologies, Cambridge, Mass.-based Joule Biotechnologies Inc. and Bonita Springs, Fla.-based Algenol Biofuels Inc. have managed to eliminate feedstocks entirely. Instead, Joule and Algenol's respective technologies utilize photosynthetic processes that consume carbon dioxide and sunlight and directly secrete ethanol.
Because the primary inputs of these two photosynthetic processes are not plant-based feedstocks, they are employable in areas that have been traditionally unable to support biofuels technologies, including desert and coastal areas that lack agricultural land.

According to Algenol CEO Paul Woods, his company's technology is completely different than second-generation ethanol technologies. There is no biomass that needs to be processed or additional inputs, such as chemicals or enzymes, that need to be added. "It's all done in one algae cell," he says. The algae employed by Algenol's technology are like tiny ethanol factories. "I think everything about our technology is just a little simpler and a little more elegant and a little easier," Woods says. "We have algae and sunlight and seawater. We introduce carbon dioxide, and that's it."

The algae are housed in bioreactors, which are large, durable, sealed plastic containers that measure approximately 5.5 feet wide by 50 feet long. The bottom third of the bioreactor houses the algae culture, while the top third is headspace in which the ethanol evaporates into as it is produced. The ethanol is collected from the headspace and purified.

Fresh water is the primary byproduct of the technology. "Right now, for every gallon of ethanol we are producing, we are providing one gallon of fresh water," Woods says. "We are not a net user of fresh water; we are actually a net provider of fresh water." Depending on where Algenol establishes its algae farms, the fresh water could be used to supplement municipal water supplies or for agricultural purposes.

Algenol currently has more than 200 region-specific enhanced algae strains. Woods stresses the enzymes are genetically "enhanced," rather than genetically modified. "Algae normally make tiny quantities of ethanol," he says. "We enhanced them and we make them so they are very specific to the regional climate that they are going to be living in. Right now, we have algae that produce more than 6,000 gallons [of ethanol] per acre per year."

Although Algenol was formed only three years ago, Woods has been working to develop the technology in his spare time for more than 25 years. He says when oil prices rose in 2006 he decided it was time to pursue the technology on a commercial level.

Woods says the technology is ready to deploy in pilot-scale and demonstration-scale facilities, but Algenol is awaiting U.S. EPA and USDA approval before moving forward. "I think we've taken a very conservative approach," he says. "We clearly don't think we have genetically modified organisms, but they are genetically enhanced, so I think we took a very conservative approach by going straight to the EPA and USDA and telling them exactly what we are doing. We are hoping these organizations give us the go-ahead to work on this on American soil."

Joule's technology, known as Helioculture, also uses a photosynthetic, direct-to-ethanol process. The technology combines sunlight and carbon dioxide in a solar converter that holds a solution of brackish or gray water, nutrients and highly engineered photosynthetic organisms which secrete ethanol.

Joule CEO Bill Sims compares his company's solar converters to a field of existing solar panels. The difference is, instead of capturing sunlight and converting it into power, Joule's technology harnesses sunlight and carbon dioxide to produce a liquid fuel. "These are flat panels that you can imagine being tilted toward the sun, and the solution is running through them in a continuous process," he says. The solution eventually ends up at a central plant where the ethanol is separated and the solution is re-circulated back through the process.

While Sims says Joule is not prepared to disclose exactly what kinds of organisms are employed by the process, he notes that the technology is projected to be able to produce 20,000 gallons of ethanol per acre per year.

Joule was established approximately two years ago, but only recently announced it was working on an ethanol production technology. "We were operating in stealth mode and made our introduction to the market at the end of July," Sims says. "We felt it was appropriate to function in stealth mode since we knew we were working on a transformational technology in a huge marketplace."

According to Sims, Joule has entered into final negotiations for a pilot plant location. Construction on that facility is expected to begin during the first quarter of next year. "Because the technology is modular, and therefore very scalable, we expect to scale the pilot facility to an industrial-sized facility also within 2010," Sims says. A commercial facility is expected to be established by 2012.

Although the technologies being developed by these companies are markedly different from both traditional corn-based and cellulosic ethanol technologies, the leaders of each company stress that a wide variety of technologies will be needed to produce 36 billion gallons of renewable fuel by 2022 and therefore the various ethanol production technologies shouldn't be pitted against one another as competition.

"It's not an either-or situation in my mind," Woods says. "I think the country really needs all these technologies to come together and provide domestic fuel sources." EP

Erin Voegele is an Ethanol Producer Magazine associate editor. Reach her at [email protected] or (701) 373-8040.