Everything 'Old' can be New Again

A biomass conversion technology developer has created a plan for large, grain-based ethanol producers to host cellulosic ethanol facilities, and reap the energy rewards.
By Kris Bevill | July 08, 2009
During his speech at the 2009 International Fuel Ethanol Workshop and Expo, Renewable Fuels Association President Bob Dinneen cautioned producers to not think in terms of new ethanol and old ethanol. "Just as with any new generation, the new generation of ethanol needs an older generation before it," he said. "Grain ethanol gives rise to the companies, the infrastructure, the trained and skilled workforce, the markets, the vehicles and even the public policies that are so essential for cellulosic ethanol."

Leaders at Inbicon A/S, a biomass conversion technology developer and subsidiary of Denmark's DONG Energy, wouldn't argue Dinneen's point. However, they believe the time has come for North American grain-based producers to begin producing "new" ethanol along with traditional ethanol and they believe they have created the technology to allow them to do it.

Early Experiments
Inbicon's beginnings date back to the 1990s when the Danish energy company Elsam began burning wheat straw for power production in Denmark and discovered operational problems that begged to be addressed. According to Inbicon CEO Niels Henriksen, early problems included high temperature corrosion, contamination of nitrogen oxide reduction catalysts, contaminated fly ash and limited amounts of straw that could be used in boilers. "The problem was alkali salts," he says. "We tried to wash the salts out and found that we could combine the washing with ethanol production." A biomass conversion project was begun with the construction of a pilot plant at the Fynsvaerket Power Station in 2003. In 2006, the company was one of six energy companies to merge and form Dong Energy, which is now Denmark's largest energy group. One year later, Dong Energy established Inbicon as a subsidiary company and transferred all of the ethanol-related technology commercialization activities to the company. "Today, we are proud to say that our process, besides producing ethanol, results in a high-quality solid biofuel without alkaline salts and a molasses that can be used for cattle feed," Henriksen says.

Process Triumphs and Challenges
Inbicon's biomass-to-ethanol conversion process works in three stages: mechanical conditioning of the biomass, hydrothermal pre-treatment and enzymatic hydrolysis. Biomass (primarily wheat straw in Denmark, but corn stover, sugar cane bagasse and other soft lignin biomass have has also been tested) is cut from large bales into small pieces before being conditioned and treated by continuously heating it to break down the lignin structure of the material. Enzymes are added and the biomass is liquefied in a reactor known as a free-fall mixer. The mixer reduces the viscosity of the biomass so dramatically, according to Inbicon, that the resulting liquid can be pumped to fermenters that have traditionally been used only for grain-based ethanol production.

Inbicon business development and marketing senior manager Christian Morgen says the pre-treatment process is the most important aspect of conversion and has been Inbicon's greatest simultaneous challenge and breakthrough. "The pre-treatment process determines the remaining process, due to the fact that we are able to maintain high dry matter content," he says. "The development of our high-gravity enzyme liquefaction technology allowed us to go from 10 percent or 15 percent dry matter in the pre-treated material to above 30 percent. The pre-treatment is the greatest challenge when it comes to the equipment, but the process makes it possible to have low enzyme consumption and high dry matter concentration going into fermentation."

The company is in the process of completing a demonstration-scale facility in the Kalundborg port facility, which will serve to demonstrate Inbicon's conversion process as well put to rest many technical and commercial uncertainties surrounding biomass-to-ethanol conversion, Morgen says. The $70 million demonstration plant is on-track to begin operations in
December, although there is still a considerable amount of work to be completed. "Commissioning this plant is every bit as big a job as a full-scale plant," he says. "It has the same amount of instrumentation, tanks [and] vessels as a full-scale plant. In order to prepare ourselves for the task at hand, we have built one-quarter scale components in our pilot facility in order to test and operate them to get experience and correct design errors. So far, these tests have been successful." Once fully-operational, the Kalundborg facility will process 110 tons of wheat straw per day and will produce ethanol as well as various co-products.

Crossing the Pond
Inbicon's next step is to incorporate its technology with 100 MMgy corn ethanol plants in North America. Well-known U.S. ethanol industry members Jeff Robert and Larry Johnson signed on with the company as G-team consultants in 2008 and are assisting Inbicon in North America. The team's first mission was to locate potential "host plants." The candidates? Any 100 MMgy grain-based production plant that is surrounded by ample amounts of corn fields, making it possible to co-locate a 20 MMgy cellulosic production plant.

By mid-June, the company had formed general agreements with three specific clients, including Global Ethanol. Johnson says the G-team reviewed all of the ethanol plants in the U.S. and has compiled corn acreage data on each plant that they have an agreement with. "We will need to collect only about 25 percent of the available corn stover within 25 miles of the plants we selected," he says. "So there's a huge amount of corn stover out there if we only have to collect 25 percent to fill the needs of our first plant."

There needs to be a huge amount of corn stover available to make the process effective, because a huge amount of feedstock is required to operate each facility. Approximately 460,000 tons of corn stover will be required to feed each 20 MMgy plant. The logistics behind collecting such massive amounts of biomass can be hard to fathom. Tonnage per acre will vary greatly, of course, but Johnson estimates that good yielding corn (approximately 200 bushels per acre) will produce 1 ton of corn cobs and 4.5 tons of stover per acre. Not all of the cobs and stover can be collected - some must be left in the fields for erosion control and to replenish nutrients, he says. But if Inbicon utilizes 2.5 tons per acre of stover and/or cobs, the company needs to have access to 200,000 acres to obtain the feedstock it requires. Johnson breaks it down even further. "If we average 500 acres per farmer contract, that'll be about 400 farmers we'll have to contract to take their stover," he says. "Just from a communication standpoint and a data collection standpoint, that's a lot of effort, a lot of communication [and] a lot of contracts that will require time and effort."

Johnson, who spent 25 years of his life as a farmer, has invested a considerable amount of time speaking to corn farmers and garnering their interest in an Inbicon project. "I have a pretty good idea what they will accept for a price," he says. "And let's face it - collecting 500,000 tons of corn stover and bringing it to collection sites and delivering it to the plantthere's no doubt it can be done. It's really quite simple. The question is going to be the economics. If we can afford to pay enough, farmers will fight to be able to deliver corn stover to us. If we have a low price, we'll be hard-pressed to sign up enough to guarantee delivery." Inbicon will base its price-paid for stover on conversion capabilities such as the cost of harvest, but there are still many unknowns and Johnson says there will need to be flexibility for the first few years of operation. However, he believes that corn stover will eventually become a commodity, similar to corn.

Dong Energy has many years of experience in feedstock logistics and can provide some mentoring to Inbicon in that area. Johnson says he saw first-hand the company's ability to handle large amounts of biomass and was very impressed. However, Dong's experience is based on wheat straw and in the U.S., corn stover is the feedstock of choice. Morgen admits that presents a challenge to the company. "We will bring our experience to the U.S., but farmers and equipment manufacturers will have to work together, and with us, to develop new harvesting techniques," he says.

Johnson says U.S. equipment manufacturers see the switch to cellulosic feedstock harvesting coming and are already working to create new methods to harvest corn stover.

Economics are the make-or-break factor of any project, and ethanol producers who are strapped for cash might need some convincing before being willing to sign on for a cellulosic project. Both Johnson and Robert stress that while the up-front capital costs for a 20 MMgy cellulosic plant will be considerably more than a grain-based plant, the benefits of hosting an Inbicon facility at a 100 MMgy grain-based plant make it worth the cost. The company's production process creates ethanol, obviously, as well as C5 molasses and lignin. The molasses can be used as a livestock feed and/or fuel for the plant's boilers. The lignin can be used to power the entire cellulosic facility with energy to spare. "We'll be reducing the host plant's energy costs by several million dollars just by using the lignin," Johnson says. "And, if we use some of the molasses as a boiler fuel to burn, we can offset all of their energy requirements."

Robert says the progression to cellulosic ethanol production is an ongoing process and it's important to remember that ethanol production has continuously evolved as technologies have become better understood. "As we move away from the grain-based era into the cellulosic era, we're not starting from scratch but we have to recognize that there's going to be a significant shift in the metrics that we've all commonly utilized to measure performance, success and the efficacy of a particular technology," he says. "As an industry, we need to be patient. Nobody is going to be able to introduce technology that is going to provide the best potential metrics that we will enjoy five, 10, 15 or 20 years from now. We're at the beginning and, from a technological perspective, no one is close to the finish line."

Johnson agrees. "[Inbicon's process] is really the first step into the future - into cleaner energy. I really think that it's the general direction that this whole industry is going. Trying to get the first 15 MMgy ethanol plants built [in the mid-1990s] was a huge challenge. Eventually, with enough hard work, we ended up getting it done. Now we're just on a new phase and a new challenge and we'll look back sometime and say that wasn't so hard.'"

Kris Bevill is the editor of Ethanol Producer Magazine. Reach her at (701) 373-8044 or kbevill@bbiinternational.com.