Aline Cotel University of Michigan Ann Arbor

Ethanol/gasoline blends are being promoted as "clean energy" alternatives and are viewed by many policymakers as key to reducing reliance on foreign oil and lowering emissions of greenhouse gases, thereby satisfying both the energy security and environmental agendas of the U.S. However, ethanol-based biofuels can pose a risk to the aquatic environment, as large fish kills attributable to ethanol spills have already been documented. Due to its complete miscibility in water, ethanol may become mixed in the water body in high concentrations. The physics of this mixing process are complex and appear to be influenced by the production of heat and variations in interfacial tension and viscosity. This research will elucidate the physics of mixing of biofuels in surface water by conducting experiments to measure the rate of mixing and entrainment in a multiphase system using DPIT (digital particle image thermometry) and DPIV (digital particle image velocimetry). The goal is develop a correlation between the degree of mixing and the relevant nondimensional parameters. The high concentrations of ethanol may solubilize hazardous compounds such as benzene from gasoline into the water column. Due to the high organic compound loading in the water column, pesticides historically present in sediment may desorb and be re-suspended in the water column. This study will evaluate the enhancement of desorption of organochlorine pesticides from sediment that may occur in the presence of ethanol and gasoline mixtures due to cosolvency effects as well as due to possible changes in the structure in sediment organic matter. The goal is to quantify the degree of desorption as a function of the composition of the mixtures of water, ethanol and gasoline, and the properties of the sediment.

In an effort to promote ethanol/gasoline blends as an alternative fuel, potentially major negative impacts on the environment have been overlooked. The assumption is the environmental impact of biofuels on surface water is negligible as "ethanol is biodegradable." Yet, large fish kills attributable to ethanol spills have already been documented. The models used for predicting concentrations of ethanol in rivers do not reflect the actual process of mixing. This research will examine the physics of mixing of ethanol/gasoline blends in water to help develop more accurate methods for predicting ethanol concentrations in rivers. Due to their solubility in ethanol, hazardous compounds present in gasoline may be solubilized in higher concentrations in a river. With a high organic contaminant concentration in the water column, pesticides historically present in sediment may desorb and be re-suspended, thus increasing their mobility. The information provided by this study will aid in the determination of the magnitude of the environmental risk posed by spills of ethanol/gasoline blends in surface waters.

Project Start
Project End
Budget Start
2013-09-01
Budget End
2017-08-31
Support Year
Fiscal Year
2013
Total Cost
$329,985
Indirect Cost
Name
Regents of the University of Michigan - Ann Arbor
Department
Type
DUNS #
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109