It has been demonstrated with repeated experiments in Phase I that ethanol, acetone, and butanediol can be produced from coal synthesis gas. Ethanol is a proven oxygenated fuel that increases the octane rating and reduces CO emissions when blended with gasoline. Ketones and diols, such as acetone and butanediol, are very similar to ethers and alcohols in chemical structure and thermodynamic behavior and may be found to be superior oxygenated fuels. The technical feasibility of biologically producing these fuels with fast rates and high yields from synthesis gas has been demonstrated. Gas retention times of a few minutes have been achieved in continuous culture experiments. Economic projections show that a return of 80 percent can be obtained from a moderately sized facility producing ethanol from coal synthesis gas. Phase II will concentrate on defining the optimal culture and bioreactor for oxygenate production. To ensure that the best possible system is developed, additional cultures will be screened for fast rates and high yields of ethanol, acetone, and butanediol. Optimal cultures will be developed to maximize rates, yields, and gas conversion. Bioreactors that achieve high mass transfer rates, as well as high cell concentrations, will be studied. Immobilized cell reactors and trickle bed reactors are especially promising for this application. Advanced bioreactor concepts, such as solidstate fermentation, nonaqueous fermentation, and high pressure fermentation, will be applied to these reactors to enhance mass transport. Equivalent retention times of seconds are conceivable for this technology. Process design and economic evaluation of the various alternatives will be used to guide the project. Phase III will be a pilot demonstration of the optimal culture and bioreactor found in Phase II. Successful completion of this demonstration will provide design data for the license and commercialization of this process.Anticipated Results /Potential Commercial Applications as described by the awardee:The potential commercial applications of this technology are extensive with a potential market for oxygenated fuels of 10 billion gallons per year. Phase I demonstrated the technical and economic feasibility of the biological production of fuel oxygenates. Phase II will optimize bacterial performance and develop engineering parameters for reactor and process design. Novel reactor concepts will be employed, and it is expected that a simple biocatalytic process with low capital and operating costs will be developed. Such a process should be readily commercialized.
