To reduce the environmental footprint, the facility will use recycled water and will generate roughly 70% of its total energy needs from lignin, a process co-product. This plant will serve as the model for future system modules for use in other facilities planned for construction.

BlueFire estimates that more than 70 billions gallons of fuel grade ethanol can be produced from the 1 billion tons of recoverable waste in the US. For Southern California, the potential exists to convert these waste streams into several hundred million gallons of ethanol fuel per year.

BlueFire Ethanol was established to use the Arkenol process for the conversion of cellulosic waste material to ethanol. The Arkenol process uses concentrated acid hydrolysis to process cellulosic biomass into simple sugars suitable for fermenting into ethanol. Arkenol improved upon the well-known acid hydrolysis process in a number of critical areas:

• Efficient acid recovery and reconcentration;

• High sugar concentration at high purity;

• The ability to ferment C6 and C5 sugars efficiently with conventional microbes;

• The ability to handle silica in biomass feedstocks; and,

• The creation of usable and marketable by-products.

Incoming biomass feedstocks are pre-treated (cleaned and ground to a reduced particle size), and then dried to a moisture content consistent with the acid concentration requirements for decrystallization (separation of the cellulose and hemicellulose from the lignin). The biomass is then hydrolyzed (degrading the chemical bonds of the cellulose) to produce hexose and pentose sugars at the high concentrations necessary for commercial fermentation. Insoluble materials, principally the lignin portion of the biomass input, are separated from the hydrolyzate by filtering and pressing and further processed into fuel or other beneficial uses.

The remaining acid-sugar solution is separated into its acid and sugar components by means of an Arkenol-developed technology that uses commercially available ion exchange resins to separate the components without diluting the sugar. The separated sulfuric acid is recirculated and reconcentrated to the level required by the decrystallization and hydrolysis steps.

The small quantity of acid left in the sugar solution is neutralized with lime to make hydrated gypsum, CaSO₄ · 2H₂O, an insoluble precipitate which is readily separated from the sugar solution and which also has beneficial use as an agricultural soil conditioner. At this point the process has produced a clean stream of mixed sugars (both C6 and C5) for fermentation.

A yeast cultured to ferment the mixed sugar stream is mixed with nutrients and added to the sugar solution where it converts both the C6 and C5 sugars to fermentation beer (an ethanol, yeast and water mixture) and carbon dioxide. The yeast culture is separated from the fermentation beer by a centrifuge and returned to the fermentation tanks for reuse.

Ethanol is separated from the beer by conventional distillation technology, dehydrated to 200 proof with conventional molecular sieve technology, and denatured with unleaded gasoline to produce the final fuel-grade ethanol product.

The still bottoms, containing principally water and unfermented pentose sugar, is returned to the process for economic water use and for further conversion of the pentose sugars.

With the appropriate organisms, the process could be adapted for the production of bio-butanol. BlueFire’s plan calls for the deployment of bio-butanol production sometime after 2009.

BlueFire can use post-sorted municipal solid waste (MSW), rice and wheat straws, wood waste and other agricultural residues. BlueFire plans to locate their cellulose conversion facilities on landfills throughout North America, initially focusing on the California fuel market.

Resources:

• Izumi Plant presentation