Research Project Summary Information
Microwave-assisted Hemicellulose Extraction from Woody Biomass and Conversion to Fermentation Sugars(ST10232-1)
New York has abundant biomass, and is heavily dependent on fossil fuels. Hemicellulose, a component of biomass, is underused in fuels and chemicals because it is difficult to convert into wood sugars, which are fermentable into a variety of products. For a biomass-based product industry to develop in New York, hemicellulose needs better processing methods. Microwaves can induce dipolar rotation in materials that contain water such as the hemicellulose component of wood. This is how food is heated in a common kitchen microwave. Internal steaming from the heat can open pore spaces. In addition to heating materials, microwaves affect the surface chemistry of materials by disorienting the charge. These are believed to be the two key mechanisms applicable to biomass processing.
Recent work by others indicates that microwave pretreatment of pulp saves 15% of energy over conventional mechanical pulping. Kraft pulping, hemicellulose extraction from softwoods, and starch hydrolysis are also reported to improve with microwave treatment. Deployment of these successes and expansion to other pulping processes and feedstock would require system design.
New York’s existing pulp paper industry has the skills and infrastructure to begin to process wood into not only paper pulp, but other bio refinery products. Integration of a microwave system into an existing mill would be needed, however.
Specific objectives included:
1) create a wood chip feedstock from willow and and maple cellulosic sources; 2) pretreat a portion of the feedstock samples via biodelignification and milling; 3) establish baseline hemicellulose extraction and acid hydrolysis data with lab digester; 4) design and fabricate bench scale microwave application systems for comparative analysis; and,5) evaluate ways to integrate the process into a paper mill and determine associated energy requirements and costs.
A successful project could help New York’s declining paper industry, or could be implemented at a wood- to- energy facility or a bio refinery. Other studies have estimated capital costs of $2.5 million per 100 daily tons of production, 60% of which, or $1.5 million, would be microwave equipment. An additional $0.15 million per 100 daily tons is anticipated for maintenance and service. Assuming a 1/3 market penetration in New York and present pulping levels, approximately 75 tons/day of hemicellulose could be generated and $1.1 million in microwave equipment could be sold. Nationwide, assuming 10% market penetration, $60 million in sales and an annual service need for $6 million would be created.
This research examined the use of microwave energy as a tool to reduce the recalcitrance of both hemicellulose and cellulose within the biomass matrix. The investigation involved exposure of willow, pine and maple wood feedstocks to microwave radiation at atmospheric pressure and pressurized conditions, with and without selected amendments, with power levels ranging from 1 kW to 40 kW. The research focused on feedstock exposure at atmospheric conditions. The goal was to establish whether increased power levels could induce superheated conditions in the wood structure capable of breaking down the woody matrix. The results showed that such breakdown tends to be primarily macroscopic and does not sufficiently disrupt the cellular wood structure necessary to enhance hemicellulose extraction or enzymatic hydrolysis beyond that which would be expected by conventional heating processes. Pressurized high temperature superheated conditions were found to be necessary to induce the desired breakdown of the biomass.
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Indigenous/Renewable Energy Resources
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R&D - Environment & Energy Res