Methods and systems for biological coal-to-biofuels and bioproducts
Methods and systems for the biological conversion of pretreated or solubilized coal or waste coal into biofuels. Coal ( 10 ) may be pretreated perhaps in a pretreatment reactor ( 13 ). Pretreated coal or even solubilized coal may be introduced into a processing reactor such as a bioreactor ( 16 ) containing a plurality of microorganisms ( 9 ) such as oleaginous microorganisms which can convert at least some of the pretreated or solubilized coal into lipids ( 19 ) or biomass ( 18 ), which then may be used directly or as a precursor for various products such as biofuels, feedstock, or the like.
1. A method for producing biofuel from coal comprising the steps of:
pretreating coal first with an alkali comprising NaOH and second with an acid comprising H 2 SO 4 to provide solubilized coal;
removing water insoluble fractions from said solubilized coal;
bioreacting said solubilized coal with at least one type of coal-utilizing bacteria;
generating biomass and lipids from said step of bioreacting said solubilized coal with at least one type of coal-utilizing bacteria;
converting said lipids into biodiesel with a transesterification reaction in a biodiesel production unit;
producing biodiesel and glycerol from said transesterification reaction;
collecting said biodiesel and glycerol;
anaerobically digesting excess biomass that cannot be converted into biodiesel;
producing methane from said step of anaerobically digesting said excess biomass; and
adding at least some of said glycerol to said step of anaerobically digesting said excess biomass.
2. The method for producing biofuel from coal according to claim 1 wherein said coal is selected from a group consisting of coal fines, waste coal, and any combination thereof.
3. The method for producing biofuel from coal according to claim 1 wherein said at least one coal-utilizing bacteria comprises genetically modified bacteria capable of bioreacting said solubilized coal.
4. The method for producing biofuel from coal according to claim 1 wherein said lipids are selected from a group consisting of diacylglycerols, triacylglycerols, and a combination of diacylglycerols and triacylglycerols.
5. The method for producing biofuel from coal according to claim 1 and further comprising a step of feeding said glycerol into an anaerobic digester to produce methane.
6. The method for producing biofuel from coal according to claim 1 and further comprising producing waste in said method wherein said waste is selected from a group consisting of unreacted coal and waste water.
7. The method for producing biofuel from coal according to claim 1 wherein said step of bioreacting said solubilized coal with said at least one coal-utilizing bacteria comprises a step of ex-situ bioreacting said solubilized coal with said at least one coal-utilizing bacteria.
8. The method for producing biofuel from coal according to claim 1 wherein said step of pretreating coal to provide solubilized coal comprises a step of in-situ pretreating coal to provide solubilized coal.
9. The method for producing biofuel from coal according to claim 1 wherein said coal-utilizing bacteria comprises a member of a genera selected from a group consisting of Rhodococcus, Streptomyces, Acinetobacter, Pseudomonas, Nocardia, Myca bacterium, Gordonia, Dietzi , and any combination thereof.
10. The method for producing biofuel from coal according to claim 1 wherein said coal-utilizing bacteria comprises bacteria from the genus Rhodococcus.