KREC: Production of Biomass Briquettes as an Alternative Fuel Source

Large quantities of fossil energy, primarily natural gas and coal, are used in the production of ethanol and biodiesel. In August of this year, the Energy Policy Act of 2005 was signed into law, which includes a significant emphasis on renewable energy efforts. Kentucky's abundance of natural resources, including forestry wastes and agricultural residues, offers a vast resource of available biomass if utilized. Direct combustion and/or cofiring of biomass have not been widely implemented due to the high transportation costs that stem from a low bulk/energy density and handling difficulties associated with moving baled biomass. However, biomass offers numerous advantages relative to coal including reduced SOx, NOx, and mercury emissions and a reduction in the net emissions of C02 as biomass is C02 neutral. The Department of Energy has focused on improving the net energy and carbon balance with existing ethanol and biodiesel plants and in proposed biorefineries and thermochemical plants. Densifying biomass into briquettes would allow renewable energy to be economically transported to facilities that require process heat and steam and could be used as the feedstock for biorefineries and thermochemical conversion plants. Biomass briquettes could also be cofired to produce green power at existing utility power plants without significant plant modifications as such plants are designed to receive and process dense, free-flowing fuels. The overall objective of the proposal is to develop an economical process for manufacturing densified biomass briquettes that can be transported to and combusted in industrial boilers. Com stover, fescue, and wood waste will be investigated as the biomass source. Potential biomass-based binders, which can lower energy consumption during production and which are located at Kentucky agricultural facilities, will be used. These binders will include coproducts (distillers grain and distillers solubles from ethanol plants), waste products from soybean oil (diatomaceous earth and residual gum) and poultry litter. Initial experiments will be conducted with an automated hydraulic press to determine the optimal biomass type, particle size, moisture content, and binder combination. Optimal performance will initially be based on the relative compressive strength of the briquettes with the energy content, attrition index, and shatter and water resistance determined for the more promising combinations. Large-scale production runs (300 lbs) ofthe most promising binderlbiomass formulations will be conducted using a continuous briquetter. Proximate analysis, ultimate analysis, major and trace elements, bulk density, heating value, attrition index, shatter and water resistance, and compressive strength of the briquettes from the production runs will be measured. Based on the results, a preliminary economic analysis of small and large-scale briquette manufacture will be conducted. This proposal supports the goals and objectives identified in the DOE Multi-Year Technical plan for developing renewable power and the procedures developed could be easily adapted for biomass densification that is required within the sugar and thermochemical platform. It also supports recommendations made in the KY Comprehensive Energy plan by augmenting coal production in Kentucky by reducing the cost of green energy via biomass briquettes that are cheaper to transport and handle while simultaneously reducing harmful emissions.