Chemists and engineers think of a “refinery” as an adjustable conversion of petroleum to many usable commodities. This approach results in a process and business that responds to changing market conditions by “tuning” its output production to suit the market.
This same concept can be applied to renewable biomass conversion processes. Biomass can be converted to usable products through biochemical and thermochemical processes. Through these processes, products like transportation fuels and industrial chemicals, fine chemicals, bio-polymers, fertilizers and pharmaceuticals, other oils and gases may be manufactured.
The Arkenol process uses concentrated sulfuric acid to convert the cellulose and hemicellulose fractions of biomass into fermentable sugars in an efficient and cost effective manner. For the first time since the petroleum boom, renewable biomass can again become a major source of chemicals for industry and society.
By weight, the largest component of plant matter is lignocellulosic material; a mixture of cellulose, hemicellulose, and lignin. Both cellulose and hemi-cellulose are long chain polymers made up of individual sugar molecules. When these long chains are attacked through either acid or enzymatic hydrolysis back to their constituent sugars, the cellulose chain splits into glucose (a six carbon sugar, hence “C6”) and hemi-cellulose breaks down into xylose (a five carbon sugar, hence, “C5”). Though cellulose is found in greater proportions than hemi-cellulose, the relative amounts of each within a plant depend upon the kind of plant and its age. In general, hemi-cellulose comprises about 20% of a lignocellulosic material. Many other commercial fermentation methods ignore this valuable fraction.
Compared to hemicellulose, cellulose is a stable molecule that is difficult to hydrolyze. This difference in stability manifests itself in different reaction rates and different reaction end points. Because hydrolysis reactions of cellulose and hemi-cellulose proceed at different rates, care must be taken to maximize yields and recover the resulting sugars prior to degradation to elemental carbon. This process control is central to Arkenol’s patents.
In order to utilize the hemicellulosic component of biomass, a viable method of metabolizing the resulting C5 sugars is needed. Techniques ranging from genetic engineering of yeast and bacteria to environmental acclimation are used to develop strains to make use of the hemicellulose. Arkenol has developed a yeast which, through the process a natural selection, has been bred to preferentially metabolize C5 sugars for the production of ethanol. When the C5 sugars have been consumed, the yeast will then metabolize the remaining C6 sugars. This results in increased product yields over competing processes.
The Arkenol process has been consciously designed to be “zero-discharge” from a process view. This means that, to the extent possible, the Arkenol process recovers and recycles all reagents used to effect the hydrolysis of cellulose. Virtually everything that comes into the plant as feedstock leaves the plant as valuable output product. However, as with any process that handles biomass, there are certain “fugitive” particulate emissions. In the Arkenol process, these types of emissions are extremely limited and of no significant consequence.
No. The reagents used in the process are not peculiar and do not require any unique handling. All of the chemicals are commonly used in many manufacturing processes such that there are established and accepted standards of handling and storage which can be implemented. Precautions to insure the safe handling of all chemicals are incorporated in the preliminary design phase of the project and are carried out through operations, Equipment and areas where chemicals are stored are equipped with safety and protective systems designed to meet or exceed all applicable regulations. Where possible, more inert chemicals are used. Impermeable containment facilities are installed in areas where accidental spills may occur. Fire fighting equipment, eyewashes, safety showers are placed to insure quick response to accidents. The commitment to safety during construction and operations is instilled upon all site personnel through oral and written instructions.