The US Patent and Trademark Office issued patent Nº 9,217,161 for a process using naturally occurring microorganisms to ferment biomass or gases directly to hydrocarbons such as hexane and octane. The fuels separate and rise to the surface of the fermentation broth, and are exactly the same as current components of gasoline.
The inventors are Professor Richard Kohn and Faculty Research Associate Dr. Seon-Woo Kim from the University of Maryland (UMD). The team was awarded a separate patent earlier this year (9,193,979) for ethanol-tolerant microorganisms that convert cellulosic biomass to ethanol. (Earlier post.) Both processes were developed based on their theory, described in in a paper published in the Journal of Theoretical Biology, that fermentation systems drive toward thermodynamic equilibrium.
The two proposed a process based on the theory to isolate and to direct the evolution of microorganisms that convert cellulosic biomass or gaseous CO2 and H2 to biofuels such as ethanol, 1-butanol, butane, or hexane (among others).
For the biogasoline process, the inventors developed microorganisms that grow on carbon dioxide, which can be obtained as a byproduct from many industrial and agricultural processes. Plants convert sunlight and carbon dioxide in the atmosphere to plant biomass, including corn grain that is currently used to make ethanol, but the efficiency of energy conversion is much lower than what can be obtained with the microorganisms. The isolated microorganisms consume hydrogen directly as well as carbon dioxide or biomass, and they excrete alkanes hexane or octane. The direct consumption of hydrogen or electricity by microorganisms that produce fuels is often referred to as “electrofuels”.
In 2010, the US Department of Energy’s Advanced Research Projects Agency – Energy (ARPA-E) created the Electrofuels Program which provided more than $50 million to universities and companies to develop microorganisms that could use hydrogen or electricity to convert carbon dioxide to liquid fuels. The concept for the program was similar to what the Maryland inventors had done, but the inventors’ laboratory was not funded.
Despite the many proclamations of success and the ramifications of the program, ARPA-E did not continue the program after it expired in 2015. The UMD inventors hope to secure funding to improve the efficiency of their process.
Richard A. Kohn, Seon-Woo Kim (2015) “Using the second law of thermodynamics for enrichment and isolation of microorganisms to produce fuel alcohols or hydrocarbons,” Journal of Theoretical Biology, Volume 382, Pages 356-362 doi: 10.1016/j.jtbi.2015.07.019