Biomass gasification is different from cellulosic ethanol in at least two major respects. First of all, it is a combustion process, not a fermentation process. As a combustion process, it can be self-sustaining once the combustion is initiated. It does not require continual inputs of energy as is the case with a fermentation process. The products of biomass gasification are syngas and heat, if the reaction is operated in an oxygen-deficient mode, or CO2 and steam (and much more heat) in the case where sufficient oxygen is supplied. In the case of the former, the syngas can be further reacted to make a wide variety of compounds, including methanol, ethanol, or diesel (via the Fischer-Tropsch reaction). A biomass gasification process followed by conversion to a liquid fuel is commonly referred to as a biomass-to-liquids (BTL) process.

However, there is one other major factor that differentiates biomass gasification from cellulosic ethanol. Biomass consists of a number of different components, including cellulose, hemicellulose, and lignin. In the case of cellulosic ethanol, only the cellulose and hemicellulose are partially converted after being broken down to sugars. The lignin and other uncoverted carbon compounds end up as (wet) waste, suitable for burning as process fuel only if thoroughly dried. Conversion is limited to those components which can be broken down into the right kind of sugars and fermented.

Gasification, on the other hand, converts all of the carbon compounds. Lignin, a serious impediment and waste product in the case of cellulosic ethanol, is easily converted to syngas in a gasifier. The conversion of carbon compounds in a gasification process can be driven essentially to completion if desired, and the resulting inorganic mineral wastes can be returned to the soil.

PureVision’s core technology separates the primary constituents of cellulosic biomass within one pressurized reaction chamber into three streams. This continuous process employs a counter-current extraction technique that removes and recovers the hemicellulose and lignin fractions in two liquid streams, resulting in a solid fraction containing a relatively pure cellulose or fiber. This patented biomass fractionation process occurs within approximately 10 minutes.

In the PureVision process, cellulosic biomass is size-reduced and fed into a pressurized reaction chamber uniquely designed for counter-current processing. The PureVision technology can be accomplished in a single stage or in multi-stages, depending upon the desired products. A distinguishing feature of the PureVision process is the ability to efficiently separate (fractionate) biomass into its three main constituents: hemicelllulose, lignin and cellulose.

In a two-stage setup, the target within the reaction chamber is to first wash out most of the hemicellulose in the form of hemicellulose sugars while keeping as much of the lignin and cellulose intact in a solid form. After the solids enter the second half of the reaction chamber, the pH, temperature and pressure are adjusted to wash and remove as much lignin as possible. These two washing stages yield (1) the xylose-rich liquor fraction, (2) the lignin-rich liquor fraction and (3) the remaining solid and relatively pure cellulose fraction.

In the first stage most of the solid hemicellulose can be converted into hemicellulose sugars. These sugars can then be fermented to produce products such as ethanol, xylitol or furfural or can be processed into a purified xylose stream. The first wash liquor fraction also contains smaller portions of the lignin, cellulose, protein, and ash components of the biomass, most of which can be recovered.

After the counter-flow washing of the hemicellulose occurs, most of the lignin and possibly the remaining hemicellulose are washed out in a second stage. This second stage wash liquor fraction contains most of the lignin and any targeted amount of the remaining hemicellulose sugars. This lignin-rich fraction is then further processed to produce a high quality, low-molecular weight lignin that can be sold as an industrial raw material to produce hundreds of industrial and consumer products. The lignin can also be used as a bio-fuel to provide energy for making electricity and steam to run the biorefinery.

The remaining cellulose fraction is between 90% to 97% cellulose, as most of the lignin, hemicellulose and extractives have been stripped off in the wash liquor fractions. Because of the high purity of the cellulose fraction, it can be sold as a pulp or enzymatically hydrolyzed into glucose requiring far less enzymes compared to competing technologies.

The PureVision process has enormous versatility and flexibility due to the many processing variables that can be achieved with steady state, counter-current processing. If the primary target is to produce a quality pulp for making paper products, the process targets the pulp specifications required by the pulp and paper industry to make paper products or dissolving pulps to make numerous industrial products. Alternatively, if the objective is to produce ethanol or other industrial chemicals, then the processing parameters will be targeted to maximize sugar production from the cellulose and hemicellulose fractions.

Verenium, based in Cambridge, Mass., is building a demonstration plant capable of converting biomass – the general name for plant material that can become ethanol – into 1.5 million gallons a year.

That demonstration plant is a necessary step toward developing a commercial-scale plant capable of producing 30 million gallons a year.

Last week, about 30 Southeast Texans – farmers, economic developers, members of the region’s BioFuels Alliance, and others went to Jennings to see the operation and learn more about it from Verenium officials.

Verenium already has an option to buy several hundred acres of land between Nome and Winnie to build a commercial-scale plant. The company also is looking at other areas along the Gulf Coast such as in Florida and Louisiana. The company plans to build several distilleries to produce ethanol.

However, the demonstration plant is an intermediate step, much the same as creating a kind of beer from the biomass is an intermediate step in distilling the pure alcohol, said Charlie Butler, human relations manager for Verenium.

“We have a master brewer on staff from Anheuser Busch,” Butler said.

That’s to control and to ensure the quality of the fermentation of the biomass early in the process.

Butler compared the start of the process with that of a pulp mill.

The biomass is fed into a chopper and is ground down to small bits. The mass comes in at about 50 percent moisture, so it contains a good deal of water anyway.

The mass is given the steam treatment and it becomes a slurry. From there, it is mixed with the company’s proprietary enzymes and bacteria, which help to create that beer of which Butler spoke.

From the beer vessel, the liquid then goes into distillation, which is where boilers come into play.

Solids drop out of the mix and are drawn off to become part of the fuel that heats the boilers.

The water that is drawn off during distillation is fed back to the steam vessels.

The pure alcohol – which might test out at 190 proof – becomes the fuel-grade ethanol.

Chuck Davis, head of commercial development for Verenium, said the demonstration plant will exist only to prove the concept.

That’s what will attract the financing to help make the commercialization possible, he said.

The demonstration plant, which will cost about $35 million to build, is about 50 percent completed and should be ready for operations by spring 2008, he said.

He said Verenium wants to be in a position to begin building a commercial plant by the end of 2008.

Construction would take 18 months to two years, he said.

The farmers were invited along because it is they who must decide whether to support such a plant with appropriate crops that they would grow expressly for Verenium’s ethanol plant.

No one at Verenium has yet put a price to the kind of crop that farmers would grow – and that’s something that farmers need to know before agreeing to a contract.

However, Verenium does need about 325,000 tons per year of biomass to produce its 30 million gallons of ethanol.

Davis said the company figures on production of 20 tons per acre of land, which would require about 16,000 to 18,000 acres of land.

Ted Wilson, director of the Texas A&M Agriculture Research and Extension Center west of Beaumont, said he thinks the 20 tons per acre is too aggressive a figure.

Wilson said he doesn’t think farmers in Southeast Texas could consistently raise that amount from each acre.

And the data for ethanol specific crops like energy cane – a more fibrous and less sucrose-heavy variant of sugar cane – or sorghum doesn’t yet exist for this area, Wilson said.

Davis was unworried.

“As we evolve, I expect costs to go down and yields to go up,” he said.

Davis said the kind of plant Verenium is pursuing is based on fibrous plants and not grain such as corn, which is now the main ethanol raw material.

The capital cost to build a distillery for the fibrous plants is higher than that for corn, Davis said. But the operating costs are lower, he said.

Richard Schroeder, a biomass consultant for Verenium, said farmers and the ethanol producer have to agree on prices or the project won’t work.

“We don’t expect anyone to grow a crop and lose money,” he said. “And we don’t expect anyone to switch crops so they can make more money. This is not ‘get-rich-quick.’

“One answer to your (Beaumont rice farmer Chuck Kiker’s) question is ‘how cheap can you grow it?’

“We want to build where we can get the cheapest crop,” Schroeder said.

He said Verenium is making a massive investment and commits to an area for “the long haul.” The service span of an ethanol plant should be 20 years, he said.

“On a per-ton basis, this is not worth what a food crop is,” Schroeder said. “But on a per-acre basis, it is feasible.”

Verenium’s kind of ethanol – called cellulosic – would yield between 1,400 and 1,800 gallons per acre. That compares with corn’s usual 400 gallons per acre, Schroeder said.

Twenty tons of biomass per acre would yield about 80 gallons per ton of biomass, he said.

Plenty of other unanswered questions remain for farmers, such as who harvests and who transports?

Also, Verenium was unable to offer specifics on a contractual minimum for a crop.

Rice farmer Alan Gaulding, who works land between Hamshire and Fannett, said Verenium’s operations were interesting to see.

“They still have a lot of work to do with the farmers,” he said.

For many on the trip, the most important thing they saw is Verenium’s intent is serious.

“They’re earnest,” said Lee Tarpley, a plant physiologist from the A&M research center.

“The importance of (the trip) is that Verenium is for real.”

San Ramon-based Chevron (NYSE: CVX) and Federal Way, Wash.-based Weyerhaeuser (NYSE: WY) each own half of the new company, called Catchlight Energy LLC. Michael Burnside, a 33-year veteran of Chevron, is CEO of the new venture. Densmore Hunter of Weyerhaeuser is chief technology officer.

Catchlight will seek biofuels made from non-food sources, particularly cellulose-based biomass. It will have offices in both San Ramon and Federal Way for the time being, said a Chevron spokesman.

Cellulosic feedstocks have many advantages over using corn to produce ethanol. Because cellulosic crops are not used for food, there is inherently less price volatility. And because a wide variety of crops can be used, they can be grown in a wide variety of geographic locations–even on marginal lands–and can, therefore, be more abundant. Plus, with certain crops, more ethanol can be produced per acre than can be made with corn.

With so many advantages, it seems only natural that we have dedicated energy crops, rather than using food crops for ethanol production.

Here are some numbers to think about.

Right now, corn yields, on average, about 160 bushels per acre, with industry predictions climbing all the way up to 300. And we get about three gallons of ethanol per bushel. That means for every acre of corn harvested, about 900 gallons of ethanol can be made.

Add in four tons of stover (converted cellulosically) per acre, with which you can produce 100 gallons per ton, and we’re looking at additional ethanol production of 400 gallons per acre–for a grand total of 1,300 gallons per acre. And that’s using two different feedstocks, with two different harvest times, two different costs and two different conversion processes.

Now consider a dedicated biomass energy crop like switchgrass, miscanthus or sorghum. These crops can be harvested, at the present time, at a rate of 20 tons per acre(very high estimate), with ethanol production of 100 gallons per ton(very advanced technology), for a total of 2,000 gallons per acre. You can see why energy crops and the cellulosic process will be huge successes.

And that’s with the current numbers. Imagine how big this would be if crop yields and gallons per acre were increased and cost were continually driven down. That’s exactly where this industry is heading.

U.S. ethanol plants produced about 5 billion gallons of ethanol in 2006, mostly from corn grain.

Mike Duffy, extension economist, 515-294-6160, mduffy@iastate.edu

The bioeconomy is the focus of research and discussion as a way to reduce dependence on imported oil, provide some relief from green house gas emissions and increase the use of agricultural products. Biofuels are a significant component of the bioeconomy. Ethanol and biodiesel are the primary biofuels used today.

In the United States, ethanol is primarily produced from corn. However, there is a considerable amount of research and development occurring to develop the capability to produce ethanol from cellulous material.

Switchgrass is one of the major plants considered in discussions of cellulous ethanol. Switchgrass (Panicum virgatum L.) is a perennial warm-season grass native to Iowa. In the past, it has been evaluated as an energy crop but primarily to replace coal. Using switchgrass to produce ethanol is a new use.

This report updates earlier production cost estimates for switchgrass. The earlier estimations were completed as a part of the study using switchgrass to replace coal. This information is available in Iowa State University (ISU) Extension publication Costs of Producing Switchgrass for Biomass in Southern Iowa, PM 1866). For more information on the agronomic aspects of switchgrass production, see the ISU Extension publication Switchgrass (AG 200).

The estimated costs of production are presented here in two sections. The first is the estimated costs. This is followed by a discussion of what could happen if we change the initial assumptions used to estimate the costs. Switchgrass costs are presented in three categories. The first is the production costs, which include establishment, reseeding and annual production. Next are the transportation costs; the final cost category considered here is storage.

Production Establishment

We make several assumptions based on 2001 research findings, with costs updates using 2007 estimates. The Information File 2007 Iowa Farm Custom Rate Survey was used to compute machinery costs. Other costs come from the Information File Estimated Costs of Crop Production in Iowa – 2007. Seed and chemical prices come from expert opinion.

Assumptions
(Note that these assumptions will be relaxed later, but they are used for the illustration that follows)

• The switchgrass is frost-seeded with a 25 percent probability of needing to reseed the stand
• The land charge assumed is $80 per acre
• Switchgrass yield is 4 tons per acre
• The switchgrass stand is assumed to last 11 years
• The reseed is assumed to last 10 years
• The interest rate used for prorating the establishment costs is 8 percent, while the operating interest rate is 9 percent
• Operating costs are assumed to be borrowed for six months
• The field is initially prepared by adding phosphorous and potassium. There is also an application of lime assumed.

It is assumed that a field needs to be reseeded 25 percent of the time. Basic ground preparation and lime are not included for the reseeding.

Assumptions

• A 4 ton per acre yield.
• 100 pounds of nitrogen (N) is used. The herbicides listed are examples. Phosphorus and potassium are at removal rates.
• Harvesting is done in mid to late November. It will be mowed, raked and baled, using a large square baler. Bales are 3x4x8 feet, with a weight of 950 pounds.
• The bottom of Table 3 also presents the total estimated costs for producing switchgrass. Production costs are the sum of the establishment costs, the prorated reseeding costs and the annual production costs.

Storage

Previous studies estimated the costs for storing switchgrass. The options considered include storing in: an open field, an open field on crushed rock covered with a tarp, an enclosed structure, and a pole building with open sides. These studies found that the enclosed building is the most expensive type of storage, but, because maintaining quality of switchgrass is very important for ethanol production, it is the method selected here. (Note that if switchgrass is used as a coal replacement, the quality consideration is not as critical and another storage option might be considered.)

The costs of storing include not only the cost for the facility or method used but also include the value of the switchgrass in storage and dry matter loss associated with the various storage methods.

The estimated storage costs are presented in Table 4 for an enclosed building. (These cost assumptions are relaxed in later discussions.)

Since there are various types of enclosed buildings, we make several assumptions.

Assumptions

• The structure is a tarped hoop type structure and holds 5,454 bales or 2,591 tons.
• Assume a cost of $12 per square foot for the finished building.
• Dimensions are 100×300 feet (30,000 square feet).
• The bales weigh 950 pounds or 0.475 tons and are 3x4x8 feet.
• The bales are stacked 20 feet high or six bales high.
• The building and area are assumed to take two acres. The extra space is for building edging, driveways and turnaround space for semi-trucks.

One issue that is not addressed is who owns the switchgrass while it is in storage. This aspect of the cost of production has not been decided. Therefore, we chose not to estimate it. There are at least two major costs that are not considered because of this decision. First, there is the value of the switchgrass over the time it is in storage. Second, and perhaps more important, is the insurance for the switchgrass and building. Storing this much dry hay could create a fire hazard.

Transportation and Handling

Transportation and storage logistics will vary depending on the situation, so again, we make some assumptions.

Assumptions

• For these estimates, the switchgrass bales are staged along the edge of the field. This cost is included in the production budget. A farmer with a typical tractor and bale fork can perform these duties.
• Another transportation cost is collecting, delivering and unloading the bales into a storage facility. A semi-trailer holding 20 tons (or 42 bales) is used to haul the switchgrass. Estimated times are 30 minutes to load the truck and 20 minutes to unload. The charge for the semi is $70 per hour.
• A typical tractor and bale hauler will not work to stack large square bales 20 feet high. More specialized equipment is needed for this task. Estimated costs of such a tractor were $20 per hour and $10.78 worth of fuel per hour. The operator charge is $12 per hour.

Table 5 shows the estimated transportation costs. These are shown in two categories; field to storage (5-mile trip) and storage to plant (30-mile trip). It is assumed that the unloading will be done at the plant at plant expense.

There are two comments regarding these cost estimates. The loading and travel time to take the semi from field to field and then to a storage facility may be underestimated. It is possible, too, that if enough farmers raise switchgrass, they can haul it to the facilities themselves. This would change the cost estimates. However, the estimates used here present the opinions of several farmers who grow switchgrass.

Table 6 shows the total estimated costs for switchgrass. This includes production, storage and transportation.

Alternative Assumptions

Estimating the cost of producing any crop will vary depending upon the assumptions made. Making assumptions is necessary, however, because we can’t model each individual farm, field, and situation. By varying some of the key assumptions we can determine areas that are the most critical in estimating the costs of production.

The Future

The future of switchgrass production depends upon its potential commercial uses. If switchgrass is used as a feedstock for ethanol, replacement for coal or other technologies, further research is needed to increase yields.

As shown in Figure 1, increasing yield will have the biggest impact on reducing the costs of switchgrass for any energy use.

The Conservation Reserve Program (CRP) may also play a role in the future of switchgrass. If green payments would be added to a switchgrass rotation on CRP land, there would be a larger economic incentive for producers. Switchgrass is a good alternative because it can be grown on marginal land and offers erosion control as well as other environmental benefits.

For switchgrass to become a commercially viable crop, there must be available markets. For cropland, there must be a sufficient economic incentive for producers to change their rotation systems. More efficient harvesting and transportation methods must be adapted to improve profitability. In addition, logistical issues must be addressed and, perhaps most important, the issues of handling and storage must be addressed.

Switchgrass can become a viable bioenergy crop. The engineering is being refined. But, before switchgrass can become viable commercially, key farmer issues must be addressed.

Due to the higher yield density of the feedstock, biofuels produced from dedicated energy crops have the potential to compete economically with gasoline and offer significant cost advantages over other biomass sources.

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bagasse) are about 65 gallons per dry ton.10 Thus, a

when short line rail transport is available.11 So, cellulosic

n Large Area: Minimum of 500,000 acres of available

n Sustainable: Cropping practice maintains or

n Reliable: Consistent crop supply history with dry

n Favorable Transport: Easy access from field to