By: Robert C. Brown, Director, and Robert Mills, Communications Specialist, Bioeconomy Institute, Iowa State University
The use of fermentation to produce ethanol from corn and other biomass is well known in the agricultural world. There are, however, other technologies that can convert biomass into fuels and chemicals. Foremost among these are thermochemical processes, which use heat and catalysis to break down biomass to intermediates that can be upgraded to transportation fuels.
One advantage of thermochemical processing is that the end result can be “drop-in fuels,” those that are fully compatible with the existing fuel infrastructure. While not perfect, these drop-in fuels are good enough to run in today’s engines without modification.
Another advantage to thermochemical processing is that most systems can work with a variety of biomass feedstocks. Often the feedstock is lignocellulosic biomass, such as corn stover, switchgrass, miscanthus, wood, etc. But thermochemical processing can also use lipid-rich biomass such as distillers dried grains and algae as well as mixed wastes from commercial and municipal sources.
There are two basic types of thermochemical processing, indirect and direct liquefaction. Indirect liquefaction includes gasification, where the solid biomass is heated to create synthesis gas, or syngas, that is subsequently upgraded to liquid fuels. Various catalysts are then used to convert the gas into alcohols or hydrocarbons. The advantages of gasification is that the process produces a uniform product and it is commercially proven. Gasification, however, requires technologies to clean the gases, which are still under development, and the capital costs can be high.
Direct liquefaction uses heat and pressure to convert the biomass into liquids which can then be further upgraded into finished products. Direct liquefaction includes pyrolysis and solvent liquefaction. In the case of pyrolysis, biomass is heated in the absence of oxygen. The process yields bio-oil, syngas, and a solid product known as biochar. The bio-oil can be upgraded to drop-in fuels. Pyrolysis can be performed at relatively small scales, allowing it to take place close to the source of biomass rather than moving biomass to one large, centralized processing facility. One of the major problems with pyrolysis is that the bio-oil is unstable, complicating its conversion into fuels.
At Iowa State University, we have invented a process to condense the pyrolysis gases in fractions, resulting in better, more stable products. The economics of fast pyrolysis are promising. In addition to producing fuels and chemicals from the bio-oil, the biochar may also have economic value. Consisting mostly of carbon, biochar can be used a soil amendment, helping retain moisture and nutrients. There is also research underway to use biochar as a filter medium for purifying water.
Solvent liquefaction, or solvolysis, is similar to pyrolysis except that it is performed in a solvent at elevated pressure. Though the fundamental chemistry of solvolysis is not well understood, the technology has promising economics. The process can upgrade bio-oil in a way similar to oil refining, and it can create sugars which can be further upgraded without expensive enzymes.
In addition to extensive research into thermochemical technologies, there are also many efforts underway to commercialize these technologies. Like all start-ups, these efforts have met with various degrees of success. There are, however, several pilot-scale systems being tested and commercial plants being built.
Bioenergy is a complex topic. There are many pathways from raw material to finished product. What’s more, bioenergy technology must be viewed in context of larger energy issues and policies. You can learn more in a book written for the general public, “Why are We Producing Biofuels,” by Robert C. Brown and Tristan R. Brown. The book is available on Amazon. You can read the first chapter for free online at: http://www.brownia.com/content/whyareweproducingbiofuels_excerpt.pdf.
Little known to our dealers and for many of our employees is the fact that our large square baler, the 2170XD and now the 2270XD, is recognized as the “King of Collection” for the baling of corn stover and wheat straw for the fledgling cellulosic ethanol industry. For over 5 years, AGCO has been working with both leading industry and university associates to develop an economical biomass feedstock supply chain. Now our balers are the centerpiece of the supply chain critical to the success of the first 3 major projects for the industry. These three projects are Abengoa’s Hugoton, KS project; Dupont’s Nevada, IA project; and POET/DSM’s project in Emmetsburg, IA. Each one is making ethanol from corn stover. Taken together these projects will require over 1,000,000 dry tons of material or roughly 1.8 million bales of which over 1.5 million will be large squares. With the corn harvest lasting only 6-8 weeks, to say there is intense activity for the baling of corn stover is a huge understatement.
Whether collecting this material for his or her self or having a professional harvester do it, this is a source of additional income for our farmers. Data has also shown an additional benefit resulting from this undertaking of residue management. With corn yields continually increasing, our farmers are producing rising amounts of corn stover as well. In fact so much residue is available after harvest that leaving it all on the field is not providing the same benefit it has in the past. The evidence is clear that removing some of the stover results in better yields in a corn on corn rotation. Uniformity of seed placement and depth, faster soil warming, less nitrogen fixing and less disease all help increase yields from 5-10%; this with the added benefit of less tilling.
Last year, during the 2013 corn harvest we had over 100 of our 2170’s and 2170XD’s at work making over 1,000,000 bales of corn stover for the ethanol industry. This amounted to over 90% of the large square balers working in this market. AGCO is working through product development to continue to improve our large square baler to support this dynamic new industry and our farmers. Better densities; data acquisition, management and evaluation; all helping to improve the operators of our equipment; and producing the most reliable and efficient large square baler in the market. This makes it easy to understand why our large square baler is considered the “King of Collection”.
If you would like to learn more about AGCO’s Biomass Solutions, please visit: www.bit.ly/AGCOBiomass.
With the new year upon us, the AGCO team wants to continue to provide you with relevant and valuable information. We want to know more about you and what posts you would like to see on the AGCO blog for 2013. We are asking you to take our brief survey so we can find out what you want to read!
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Agri-Trade is a treat for the whole farm family and an opportunity for the next generation in agriculture to see progress and products first-hand. There will be presentations and seminars all week, on a variety of subjects. Agri-Trade is the place to learn, first-hand, about the machinery and products that you need to farm successfully. All of the best equipment is here, with knowledgeable manufacturers reps, information and answers to your questions. For more information, please visit www.agri-trade.com.