Now, let’s go into a little more detail, so there can be a comfortable understanding of how simple the process really is.  We will use ethanol as our example biofuel using the GFT process.  The GFT process utilizes gasification (which we call reformation) and Fischer-Tropsch reaction to take any carbon-containing feedstock, convert it to a synthesis gas (or syn gas), and then configure those molecules into the target fuel of choice.  This is followed by traditional distillation and condensation to purify and liquefy the compounds.  Gasification is not new technology and has been used in the coal industry for decades.   Gasification combined with Fischer-Tropsch has also been utilized since the early 20th century, notably by the Germans in World War II after the allies took out their access to petroleum.  The South Africans have been using this process to make gasoline from coal since the 1960s.  Biomass gasification simply uses biological materials (like wood or switch grass) which have extremely high carbon content instead of coal. 

How Does It Work? 

So how exactly does one go from a pile of wood chips to a drum full of ethanol?  In order to understand the technology, we must first understand the make-up of the raw materials and end-products.  Alcohols, gasoline, diesel fuel, jet fuel, etc., are all organic compounds.  That is, they are based on carbon.  Their formulas are different, but they all contain carbon and hydrogen and the alcohols also contain oxygen.  What is wood made of?  Wood is made almost entirely of cellulose (including hemi-cellulose) and lignin.  There are trace amounts of other items like metals, and there is of course a tremendous amount of water, but the “woody” mass is essentially cellulose and lignin.  Cellulose is made up of glucose (a sugar) molecules, hemi-cellulose is glucose and other sugars, and lignin is mostly phenols.  Glucose is made of carbon, hydrogen, and oxygen as are all other sugars in varying formulas.  Phenols are also made up of carbon, hydrogen, and oxygen.  You can see that the basic chemical ingredients for wood are exactly the same as they are for liquid fuels – just in a different form.  If we could break up the glucose (and other sugar) and phenol molecules to get at their carbon, hydrogen, and oxygen, we can reconfigure those elements to make fuels.   That is the basis of our process technology approach.  The gasification part of the technology (reformer – ethanol unit #1), uses heat and pressure to break down those molecules into carbon and oxygen - in the form of carbon monoxide and carbon dioxide - and hydrogen.  This process is called pyrolysis and is different from combustion in that the wood raw material is not consumed in the process like a fuel.  At this point, the carbon monoxide, carbon dioxide, and hydrogen are still in the form of a gas.  This is the syn gas.  Interestingly, this part of the process is the most complicated and critical, because the syn gas has to be just right in order for the next step to work properly.  How do we convert the syn gas to fuel?  The syn gas then goes to the Fischer-Tropsch reactor (ethanol unit #2) which uses a specially designed catalyst package to re-assemble the molecules into the fuel we need.  For example, ethanol has two carbons, six hydrogens, and one oxygen and is assembled like; CH3-CH2-OH with the “OH” attached to the second carbon.  The catalysts simply take the available carbons, hydrogens, and oxygens that were released from the wood chips and “re-assemble” them in the form of ethanol molecules.  At this point, we still have a gas, so the next step is easiest of all; we simply use traditional distillation and condensation (cooling) equipment to purify the ethanol stream and to make it a liquid.  The material is then ready for commercial sale – it’s that simple. 

Fermentation processes, on the other hand, must have those sugars intact as sugars (carbohydrates) and use micro-organisms to convert those sugars to alcohols.  Cellulosic fermentation uses microbes to hydrolyze the cellulose into constituent glucose molecules first and then they can be converted, using more micro-organisms, into ethanol.  

Conclusion