Assessment of straw biomass feedstock resources in the Pacific Northwest

Straw that is produced as a coproduct of cereal grain and grass seed production on 24,000 km2 in the Pacific Northwest states of Idaho (ID), Oregon (OR) and Washington (WA) has potential as a bioenergy feedstock. Previous attempts to develop approaches to convert straw to energy based on transporting straw to a conversion facility were uneconomical. Rising energy prices and the availability of new technologies have renewed interest in converting these lignocellulosic residues to energy products, especially liquid fuels [Perlack RD, Wright LL, Turhollow AF, Graham RL, Stokes BJ, Erbach DC. Biomass as feedstock for a bioenergy and bioproducts industry: the technical feasibility of a billion-ton annual supply, 2005. http://feedstockreview.ornl.gov/pdf/billion_ton_vision.pdf (website accessed December 2007). [1]], but information on the distribution of these resources is lacking. Development of an economic approach to convert this straw to energy will require an assessment of the regional distribution of available straw to identify an appropriate scale of conversion technology that optimally reduces straw collection and transportation costs. We utilized county-scale US Department of Agriculture (USDA) National Agricultural Statistical Service (NASS) data to quantify total grass seed and cereal straw production in each county of ID, OR and WA, subtracted the county-specific quantity of field residue for each crop, and developed an estimate of available straw, that remaining after sufficient straw is returned to the soil for conservation. At current straw yields, over 6.5 Mt of straw in excess of that required for conservation purposes are available in the region. This straw is distributed across the landscape at an average density of 2.4 Mg ha−1 and in many locations will require small- or local-scale technology to enable economical conversion of the feedstock to energy.