Applications of biomass as a renewable fuel source have recently gained interest as supplements to existing energy supplies. Biomass energy, commonly known as biofuel, derives from living organisms 
(e.g., trees, switchgrass), and is an attractive alternative to traditional fuel sources due to the ability of living organisms to fix CO2 from atmospheric sources. Carbon dioxide fixation results in carbon cycling, and a zero net output of CO2 to the atmosphere. Additionally, biofuels are renewable energy sources, in contrast to fossil fuels, making them attractive options for longterm energy supplies.
Recently, Dr. Susan Burns and Dr. Kimberly Kurtis of the School of Civil and Environmental Engineering at Georgia Tech, with support from the Southern Company, have initiated an investigation of the engineering properties of fly ash produced from the burning of biomass‐derived fuel sources. Fly ash is the lightweight residual material resulting from the combustion of a fuel source, with coal combustion being the most well known and prevalent source of fly ash. The materials resulting from the high temperature combustion of fuel are highly oxidized and can be reactive components of a variety of construction materials like concrete. Combustion of biomass fuels also produces a biomass‐derived fly ash, and the engineering properties of this material are less well‐defined when compared to the properties of coal‐derived fly ash.
CEE doctoral students Chris Shearer and Nortey Yeboah are working under Drs. Burns and Kurtis to 
quantifying the engineering properties of biomass fly ash which is produced when the biomass is burned as the sole fuel source, or when the biomass is co‐fired with coal as the primary energy input. Biomass fly ash is being characterized in terms of type of fuel source (hardwood versus softwood), size of the biomass input (chips versus whole tree), and geographical and environmental characteristics of the biofuel such as rainfall and growing temperature. Understanding of these properties will allow the researchers to identify trends in the fundamental fly ash particle characteristics, including mineralogy, surface area, surface charge, particle size distribution, and carbon characteristics that result from the combustion of biomass and co‐fired biomass/coal.
Ultimately, Dr. Burns and Dr. Kurtis will examine applications for the productive reuse of the biofuel‐derived waste. Approximately 60% of the fly ash (more than forty million tons) currently produced as a by‐product of electricity generation in the U.S. is disposed in landfills, making reuse applications an especially appealing alternative to land disposal.
For more information about this research, contact Dr. Susan Burns or Dr. Kimberly Kurtis.