What is a “bio-refinery”?
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.
What is the “Carbohydrate Economy?
One hundred years ago most of our fuels, construction materials, clothes, inks, paints, and even synthetic fibers and chemicals were made from plant matter. Then petroleum flooded the economy and a new industrial era began. By the 1980s less than 5 percent of our industrial products and fuels came from biological materials.
However, new technologies, new laws, and increasingly environmentally aware public are ushering in a new materials base for the 21st century; plant matter. We call it a “carbohydrate economy”.
The environmental benefits of a carbohydrate economy are significant. Bio-based chemicals generate a tiny fraction of the pollution generated by the manufacture and use of petrochemicals. The use of biological fuels generates far less carbon dioxide than the use of fossil fuels. Finding commercial uses for the 300 million tons of cellulosic waste generated annually in our rural and urban areas would itself achieve important reductions in pollution. Switching to grasses or crops for making paper and construction materials would allow us to preserve old growth forests.
The carbohydrate economy promises economic as well as environmental benefits. Thousands of locally owned biorefineries that make multiple products from a single biological feedstock could inject billions of dollars into rural economies. The knowledge generated from this new manufacturing sector could become an important export.
On a molecular basis, there is no difference between a chemical derived from sugar and the same chemical derived from petroleum. The advantage of sugar-derived chemicals lies in their origins and their renewability.
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.
The Arkenol process has been designed and engineered to avoid significant impacts to the community and the environment. The plant can be designed, constructed, and operated in accordance with or better than all applicable regulations. Therefore, it is no more difficult to permit the Arkenol process than to permit similar industrial facilities. In fact, the unique environmental benefits of the Arkenol process provide an edge for permitting. Arkenol plants deliver visible environmental and socioeconomic benefits which make them attractive solutions to local problems. Arkenol has already successfully permitted a 15 mgpy rice straw-to-ethanol facility to be
Yes, Arkenol can license its technology to qualified entities for their own project development. However, Arkenol prefers to offer more that just a license. With its team members, Arkenol can provide turnkey engineering, procurement, construction, and operations services. Arkenol will work with developers around the world to license its technology and on an individual project, a corporate or a regional basis.
The Arkenol process, protected by national and international patents, 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.
All plant structures are composed of many-linked chains of sugar, cellulose and hemicellulose, which are surrounded by lignin; a glue-like carbon molecule that holds these sugar polymers together. In the first step of the Arkenol process, concentrated sulfuric acid is used to attack the long chain cellulose and hemicellulose molecules, breaking the links of the chain into their simple sugar components. This decrystallization and hydrolysis occurs at relatively low temperatures and pressures. The resulting solution now contains sugar, sulfuric acid, water, and lignin (an inert solid). The lignin is separated from this acidic solution using a filter press. The acidic sugar solution then continues on to a chromotographic separation unit which effectively separates the acid and sugar solution into a pure sugar stream and a pure acid stream. The acid stream, now dilute, is recycled and reconcentrated for further use. The now slightly acidic sugar stream (the separation of the streams approaches 100%) is neutralized with lime; forming gypsum. The gypsum is filtered from the neutralized sugar solution which is sent on for fermentation to the myriad of possible products.
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.
Numerous independent reviews confirm the soundness of the science which defines the technical approach. The authors range from independent engineers and consultants, such as Arthur D. Little, R.W. Beck, and Purdue University (for the USDA), to in-house reviews by Babcock & Wilcox and Tenneco Energy, and to ethanol plant design engineers including, Lockwood Greene, Zurn/NEPCO, and Raphael Katzen Associates International. Arkenol’s proprietary improvements have been protected via various patents, patent applications and trade secrets.
Process economics. Arkenol’s founders have directed their engineers to follow the “dumb iron” approach to pilot plant construction and operation and full scale engineering. With recourse to only private funds, Arkenol labored to contain costs through benchtop research to pilot plant construction. This was possible because the focus was not on developing new technology but on identifying and correcting the economic deficiencies of a proven process – concentrated acid hydrolysis.
Arkenol’s improvements to overall process efficiencies have resulted in higher concentrations of sugar and acid which require less energy to ferment and distill and reconcentrate for reuse. Arkenol’s process improvements have also resulted in higher sugar yields per cellulose unit further enhancing process economics.
Of lesser importance, perhaps, is Arkenol’s selection of the concentrated acid hydrolysis process which provides higher tolerance for variations in feedstock compositions. Genetically enhanced organisms used in simultaneous saccharification and fermentation processes are less robust and prone to destruction due to the required mechanical handling of the pumping processes used in continuous fermentations. For instance, these organisms are affected by co-factors present in feedstocks like municipal solid waste that, without pre-processing, result in the inhibition or even destruction of the organisms used. Concentrated sulfuric acid is an effective screening agent for these co-factors.
To summarize, Arkenol’s scientific and process improvements are described as follows:
It is useful to note that unlike hydrochloric and hydrofluoric acids used in competing processes, sulfuric acid is not toxic.
What kind of feedstocks can be used with the Arkenol process?
The energy of the sun is locked in the cellulose molecule. Because biomass and biomass-derived products contain cellulose in some proportion, the number of feedstocks suitable for the Arkenol process is huge. Suitable feedstocks include:
This astounding selection of feedstock provides a flexibility in matching available feedstocks with regional product markets.
Besides ethanol, what other products can be produced via the Arkenol process?
The Arkenol process extracts and converts cellulose and hemicellulose to C6 and C5 sugars. In a 1978 article published in Science, DuPont provided a review of over 250 chemicals that are manufactured today from petroleum and were once manufactured from sugar. Many of these are niche chemicals with small markets and high barriers to entry. The others are comprised of commodities whose manufacturing costs are optimized by the economies of scale found in the mega-refineries of the world. In order to compete in today’s market place with these petroleum-derived commodity chemicals, it is critical to begin with significantly lower feedstock costs. The Arkenol process provides this cheaper sugar feedstock, and because of its geographic flexibility, can be sited near its ultimate customers to permit lower transportation costs.
In additional to ethanol, there are other commodity chemicals in wide use whose markets can assist to springboard the Carbohydrate Economy. These can be divided into three general classes of chemicals: organic acids (e.g., citric acid, levulinic acid, acetic acid, oxalic acid), solvents (e.g., butanol, acetone, isopropanol, ethanol, furfural), and other chemicals (e.g., n-butyl butyrate, acetates, butanediols)
For a list of potential end products click here www.ilsr.org.
Aside from the primary fermentation products, the Arkenol process produces gypsum (calcium sulfate) and lignin in marketable quantities. Gypsum has markets in industry (e.g. road base, wallboard) and in agriculture (e.g., soil conditioner). Lignin also has markets in industry and in agriculture. Lignin may be used as a low-sulfur, cleaner-burning solid fuel with a higher heating value that ranges about 8,000 Btu/lb. As a soil amendment, lignin contains the minerals and nutrients that were originally extracted from the soil through the metabolism of plants. Its consistency is like peat moss, and in large scale agricultural applications, may be returned to the soil using conventional manure spreading equipment.
Because the Arkenol process recovers and recycles over 95% of the sulfuric acid used in the decrystallization and hydrolysis of cellulose, the amount of gypsum produced is significantly lower than older, less advanced processes.