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United States Department of Agriculture

Agricultural Research Service

Title: Assessment of Straw Biomass Feedstock Resources in the Pacific Northwest

Authors
item Banowetz, Gary
item Boateng, Akwasi
item Steiner, Jeffrey
item Griffith, Stephen
item Sethi, Vijay - WESTERN RESEARCH INST
item El Nashaar, Hossien

Submitted to: Biomass and Bioenergy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 17, 2007
Publication Date: February 8, 2008
Citation: Banowetz, G.M., Boateng, A.A., Steiner, J.J., Griffith, S.M., Sethi, V., El Nashaar, H. 2008. Assessment of Straw Biomass Feedstock Resources in the Pacific Northwest. Biomass and Bioenergy, 32, 629-634.

Interpretive Summary: Straw is produced as a coproduct of cereal grain and grass seed production on 6.2 million acres in the Pacific Northwest of the U.S. Historically, much of this straw was burned because markets for the straw were limited and disposal of the residue was required for subsequent seed and grain production. Air quality legislation has severely restricted the use of burning and consequently, there is a need to develop cost-effective ways to remove or market excess straw. Previous attempts to develop profitable markets for this straw included its use as feedstock to produce energy, but the high costs of collecting and transporting straw to a conversion facility limited the success of these efforts. In addition, chemical constituents of straw caused slagging and corrosion in previously used gasification reactors. Rising energy prices and the availability of new technologies have stimulated renewed interest in conversion of these residues into energy products, especially liquid fuels. Development of a successful approach will require technology appropriate for handling straw chemical constituents as well as strategies to significantly reduce the costs of collection and transportation of the straw. We evaluated the feasibility of developing farm-scale conversion technology to enable on-farm energy production utilizing independently-developed gasification and microchannel technologies. A limiting factor is the lack of farm-scale gasification technology that can operate with straw feedstocks that contain high quantities of silica, potassium and other corrosive and slag-causing minerals. We found that among cultivated turf and forage grasses there are significant differences in apparent silica accumulation may be useful in developing new germplasm with improved feedstock characteristics. At current straw yields, over 6.2 million tons of straw in excess of that required for conservation purposes can be collected from the region. There is potential to harvest straw from an additional 2.8 million acres currently enrolled in the Conservation Reserve Program (CRP) and potential exists to harvest straw feedstock from buffer strips during historically dry periods of the year when buffer function is not required. A new dual-stage farm-scale gasification reactor has been tested that has the capability to produce syngas from straw feedstocks without slagging, although design and operational modifications are needed to enhance carbon conversion efficiency. Coupled with existing microchannel catalytic Fischer-Tropsch technology to convert gasified straw to liquid fuels and assuming conservative yields of mixed alcohol liquid fuel from straw, there are sufficient reliable quantities of straw to provide over 6% of the region’s current liquid fuel consumption. Development of economic farm-scale technologies appears to be feasible and necessary to reduce the costs of straw collection and transportation.

Technical Abstract: Straw is produced as a coproduct of cereal grain and grass seed production on 6.2 million acres in the Pacific Northwest of the U.S. Some of this straw residue is returned to the soil for conservation purposes, but markets for excess straw are limited. As a consequence, much of this straw was burned historically. Recent legislation restricting the use of burning has created a need to develop cost-effective ways to remove or market excess straw. Previous attempts to develop profitable markets for this straw included its use as feedstock for thermochemical (gasification) approaches to produce energy, but the high costs of collecting and transporting straw to a conversion facility limited the success of these efforts. In addition, chemical constituents of straw caused slagging and corrosion in previously used gasification reactors. Rising energy prices and the availability of new technologies have stimulated renewed interest in conversion of these lignocellulosic residues into energy products, especially liquid fuels. Development of a successful approach will require technology appropriate for handling straw chemical constituents as well as strategies to significantly reduce the costs of collection and transportation of the straw. We evaluated the feasibility of developing farm-scale conversion technology utilizing independently-developed gasification and microchannel Fischer-Tropsch technologies. The limiting factor is the lack of farm-scale gasification technology that can operate with straw feedstocks that contain high quantities of silica, potassium and other corrosive and slag-causing minerals. Genotypic differences in apparent silica accumulation may be useful in developing new germplasm with enhanced feedstock characteristics. At current straw biomass yields, over 6.2 million tons of straw in excess of that required for conservation purposes can be collected from the region and there is potential to harvest straw from an additional 2.8 million acres currently enrolled in the Conservation Reserve Program (CRP). Potential also exists to harvest straw feedstock from buffer strips during historically dry periods of the year when buffer function is not required. A new dual-stage farm-scale gasification reactor has been tested that has the capability to produce syngas from straw feedstocks without slagging, although design and operational modifications are needed to enhance carbon conversion efficiency. Coupled with microchannel catalytic Fischer-Tropsch technology to convert gasified straw to liquid fuels and assuming conservative yields of mixed alcohol liquid fuel from straw, there are sufficient reliable quantities of straw to provide over 6% of the region’s current liquid fuel consumption. Development of economic farm-scale technologies appears to be feasible and necessary to reduce the costs of straw collection and transportation.

Last Modified: 9/10/2014