This SBIR Phase I project enables the research and development of a new hybrid fixed-fluidized biomass gasifier design that allows for a higher carbon conversion efficiency over a far wider range of feedstocks than what current commercially available biomass-to-electricity technologies are able to offer. This technological development serves the public interest by increasing the economic viability of renewable waste-to-energy projects. Biomass waste accumulation from forest thinning and agriculture generate approximately 166 million tons of biomass each year in the United States alone and is problematic to dispose of due to air quality regulations, which restrict open burning, and tipping fees from waste sites that have to mitigate methane production from decomposition. Instead of open burning or uncontrolled decomposition, biomass gasification enables these resources to be utilized locally to replace fossil fuels and to sequester carbon to mitigate climate change. Biomass energy is currently limited by feedstock requirements (typically restricted to standardized wood pellets), which has constrained the implementation of biomass-to-energy plants in the U.S. This project seeks to greatly expand the feedstock characteristic options available for biomass energy to offer an off-the-shelf commercial solution to sustainable energy project developers in the U.S. and organizations responsible for biomass waste processing. Approximately 150 jobs are expected to be generated in the US to support these two industries, through manufacturing and project development, as well as associated sales and income tax revenue.
Commercially available downdraft and fluidized bed biomass gasifiers are hindered by three main root technical problems that significantly constrain the economic viability of state-of-the-art biomass-to-electricity projects: 1) each is limited by the small range of feedstock particle sizes it can process; 2) maximum allowable reaction temperatures are limited due to ash fusibility temperatures; and 3) the ash fusibility temperature is too low to maximize tar cracking. The proposed technical solution separates the vaporized tar and small feedstock particle sizes from the larger particles and high ash solid charcoal. This separation decouples the temperature requirements and allows for greater tar cracking potential at higher temperatures while maintaining a lower oxidation temperature for the char to increase carbon conversion efficiency??overcoming all three root technical problems. The goal of the research is to identify and validate the dimensions and parameters required to maintain stable biomass gasification with improved tar cracking efficiency and reduced ash clinkering risk. The scope of the project includes proving the proposed technology at a gas capacity of 20kW, which will be scaled up to a 150kW to be able to provide the algorithm to dimension the technology at any scale. The development of a fully fuel agnostic gasifier is the so-called holy grail of gasification and the successful completion of the project will be a significant step toward this goal, enabling the technology to scale successfully and be disseminated in almost any market or sector with a biomass waste stream.
