Bioenergy is an integrated life science company with a clear mission to develop products that improve lives. Our core technology is centered on the simple carbohydrate, D-ribose, and the dramatic metabolic impact it has on restoring energy in the body.
D-Ribose amplifies the body's natural response to metabolic stress, protects tissues from oxygen deprivation, and stimulates recovery following a hypoxic or ischemic insult. For healthy people this translates to more energy and less fatigue, greater exercise performance over time, and faster recovery from exercise or overexertion. For those with compromised heart or muscle function it means they can do more and enjoy a higher quality of life. No other compound, including natural bioactive compounds or drugs, can replace D-ribose in its important metabolic role in the body.
Bioenergy is commercializing products that transcend the spectrum from specialized nutrition to ethical pharmaceuticals, providing a continuum of care. Our clinical nutrition and branded nutraceutical products provide metabolic support to stressed hearts and muscles, and our bioactive ingredient, Bioenergy RIBOSE™, is widely used in foods and nutrition as an energy enhancing nutraceutical to fight fatigue and accelerate energy recovery. The Company's pharmaceutical division is developing D-ribose applications that will significantly expand the beneficial use of ribose in health preservation, and our cell technology subsidiary is developing cutting edge technology to help improve our blood supply.
20 Eylül 2007 Perşembe
Bioenergy
Biotechnology for biomass conversion
Bioconversion of corn starch
Corn starch is converted into ethanol through wet or dry milling processes followed by saccharification and fermentation. Technology for the fermentation of starch was first developed many thousands of years ago for beer making, but today's processes are much more efficient. Enzymatic saccharification used for converting starch into fermentable sugars employs glucoamylases that operate at elevated temperatures. Fermentation of the resulting glucose is carried out within a few hours, and the ethanol is distilled and dehydrated using contemporary technology that consumes relatevely little energy. In addition to ethanol, modern wet milling plants produce corn oil and animal feed products. These byproducts offset much of the grain price and retain the principal nutritive value. Fermentation of corn starch is an established but still evolving technology. Further improvements can be expected in the utiliztion of corn fiber byproducts the the implementation of even better distillation technology. Bioconversion of lignocellulosics
Bioconversion of lignocellulose to ethanol requires pretreatment, saccharification and fermentation. Pretreatment requirements vary with the feedstock and are often substantially less in the case of various paper and hydrolysis waste streams.
Cellulose saccharification
Cellulose saccharification is the process of turning polymeric lignocellulosic materials into fermentable sugars. this can be accomplished by a number of processes including acidic and enzymatic hydrolysis.
Pretreatment technologies
Pretreatment is essential for bioconversion of most lignocellulosic materials. Pretreatments include mechanical size reduction, heat, steam, steam explosion, autohydrolysis, acid hydrolysis, alkali treatment, ammonia, chemical pulping, solvent extraction, and various combinations of these separate processes. The purpose of pretreatment is to maximize subsequent bioconversion yields and minimize the formation of inhibitory compounds. With heterogeneous waste streams such as municipal solid waste (MSW), it may be necessary to go through some sort of classification process such as air classification or magnetic separation before carrying out pretreatment.
Classification processes
Air classification is used to separate mixed MSW into light and heavy fractions. It was developed to produce streams for paper recovery and combustion. In this process, a shredded waste stream is fed into a cyclone with air injected from the bottom. The light fraction consisting of paper and plastics exits from the top; the heavy fraction with wood, glass and metals exits from the bottom. Magnetic separation is used to remove ferromagnetic materials. Shredded waste passes through a magnetic separator on a continuous conveyor belt. Hand sorting is used to recover high value materials such as aluminum and some plastics. Recycling is best done by the consumer at the source. It is far easier to keep recoverable materials separate than it is to mix them and have to separate them later.
Mechanical size reduction
Requirements for mechanical size reduction vary with the feedstock. In the case of green wood, chipping is generally essential. The smaller the chip, the faster the pretreatment chemicals or steam can penetrate into the wood. Because wood is a thermal insulator, heat transfer into large chips can be uneven. However, if chips are too small for the dimension of the reactor employed, excessive packing can occur and steam does not penetrate appropriately into the bed. Chip sizes range from 3/4" to 1/8"In the case of agricultural residues, particle size reduction can often be done simply with grinding. For dry corn or soybean residues, density is often lower than what is desirable, and particle size reduction is not an issue
Municipal solid wastes present a particular problem because of their extremely heterogeneous nature. Large quantities of plastics, wood, metals and other materials are often present. If certain heavy metals are present in the mixture when acid is added, they can create severe downstream problems in fermentation and product formation. Batteries should not be a part of the waste stream.
Steam treatment in a tumbling reactor is a convenient way to facilitate separation of plastics and fibers while increasing digestibility of MSW. In this process, garbage is introduced into a large, cylindrical, horizontal autoclave that is slowly rotated on its side while steam treatment takes place. The plastic materials collapse, and the fibrous materials for a pulp. Metals and other non-fibrous materials (e.g old shoes) are readily separated on a grating after treatment.
Autohydrolysis
Autohydrolysis is the process of converting lignocellulose into fermentable sugars by exposure to high temperature steam. Many lignocellulosic materials contain significant quantities of acetylated hemicellulose. Steam releases these in the form of acetic acid which subsequently carries out a partial hydrolysis of the hemicellulosic and cellulosic sugars. the principal disadvantage of this approach is that sugar yields are generally very low.
Acid hydrolysis
Acid hydrolysis is often used as a pretreatment because it can be adapted to a wide variety of feedstocks. Except in the case of strong hydrochloric acid hydrolysis, it is generally carried out at elevated temperature (100 to 240 °ree;C) for various lengths of time. At higher acid concentrations, it can be carried out at temperatures as low as 30°ree;C. Generally an inexpensive process, acid hydrolysis may also produce large quantities of degradation byproducts and undesirable inhibitory compounds in higher temperature (low concentration, greater than 110°ree;C processes).
Strong acid hydrolysis
Sulfuric acid can be used in concentrated form, but it is far more commonly used in a dilute solution of 0.5 to 5% sulfuric acid (on a w/w basis with dry solids). The concentrated form usually employs a method of separating and recycling the acid catalyst limiting the total acid losses to approximately 3%, or the same as the dilute process. Use of the concentrated acid however, allows lower temperature and pressure hydrolysis with fewer byproducts produced.
Concentrated hydrochloric acid (47%) is sometimes used for strong acid hydrolysis because it is relatively easy to recover. Hydrolysis with concentrated hydrochloric acid gives one of the highest sugar yields of any acid hydrolysis process. It is carried out at room temperature. The chief drawback is that it is highly corrosive, volatile, expensive and almost complete recovery is essential in order to make the process economical..
Weak acid hydrolysis
Sulfur dioxide is often used in combination with autohydrolysis because it gives better sugar yields and helps to modify lignin for subsequent extraction or recovery. Sulfur dioxide combined with steam is particularly effective as a pretreatment for enzymatic cellulose saccharification.
Dilute acid hydrolysis
Dilute acid hydrolysis with 1 to 5% sulfuric acid is generally considered the most cost-effective means of hydrolysing wood and agricultural residues. Yields of hemicellulosic sugars can be 80 to 95% of theoretical. Yields of glucose from cellulose are generally less than 50% but can approach 55% at elevated temperatures.
The ARKENOL process
The following information has been provided by Mark Carver of ARKENOL, and he should be contacted for further information.Recent advances in the chromatographic separation of strong acid hydrolyzate has improved the economics of the process.
The ARKENOL concentrated H2SO4 process uses several recent technological advancements to commercialize a Bergius derivative process. Advancements in cross-linked plastic coatings allow the use of lower cost materials in equipment selection and construction and with the lower temperature allowed by higher acid concentration, one can use near atmospheric pressure process operations.
The integration of commercial chromatographic separation equipment allows the near complete recovery of the acid catalyst without large energy penalties. Both environmental and genetic engineering have produced bioorganisms which readily metabolize both C5 and C6 sugars produced from the lignocellulose.
The ARKENOL process separates the lignin, ash and insolubles from the high concentration sugar and acid stream leaving a near zero solids stream for chromatographic separation. Separation recycles the acid for reconcentration and sugar for neutralization and nutrient addition.
Simultaneous fermentation of the C5 and C6 sugars in about 70 h hours converts more than 90% of these sugars into ethanol and CO2. Maintaining higher concentration sugars through the process allows 7-8% beer for feed to the distillation and dehydration columns. Clear sugar streams allow the recovery of bio-organisms for recycle as well as the recovery of reusable water from the distillation column bottoms. The lignin, ash and insoluables may be further processed for byproducts or used for biomass fuel (8000 BTU/Dlb) or composting.
The process economics have been evaluated for 12-20 MMGPY (million gallon per year) ethanol production plants receiving 400 to 650 TPD of 75% C+H content, 10% moisture biomass. Average collection costs range from $6 to $20/ton for the biomass collected within a 25 to 50 mile radius of the plant. 30 year cash on cash IRRs are generally above the 12% range with leveraged returns even higher.
The ARKENOL process has been evaluated by several internationally known independent engineering firms, extensively (4 years) reviewed and permitted for a California cogeneration project, demonstrated at laboratory scale for five years, operated for almost two years at a 1/2 TPD pilot plant on rice straw and sorted municipal paper waste feed streams, has had two $100 million plus engineering and construction firms prepare and evaluate preliminary engineering and cost estimate packages and is in the process of obtaining a $45 million financeable process guarantee from one of them.
They have several international patents pending on the process and are pursuing international as well as domestic development opportunities.
The first plants should be financed and starting construction by late 1996 or early 1997.
Biomass Feedstocks
Agricultural crops
Sugarcane, sugarbeet, corn, and sweet sorghum are agricultural crops presently grown commercially for both carbohydrate production and animal feeds. Sugarcane, corn and sweet sorghum are efficient at trapping solar energy because they are all "C4" plants. They use special biochemical pathways to recycle and trap carbon dioxide tht is lost through photorespiration. Sugarbeets are efficient because they store their carbohydrate in the ground. Sugarcane was the basis for the World's first renewable biofuel program in Brazil. Corn is the basis for the present renewable ethanol fuel industry in the United States. The sugars produced by these crops are easily fermented by Saccharomyces cerevisiae. The sucrose produced by sugarcane, sugarbeet, and sweet sorghum can be fermented directly after squeesing them from the crop. Corn traps its carbohydrate largely in the form of starch which must first be converted into glucose through saccharification with glucoamylase. The residues left over after removing fermentable sugars can also be utilized. In some cases they end up as animal feeds, but many agricultural residues can be converted into additional fermentable sugars through saccharification with cellulases and hemicellulases. The hemicellulosic sugars are not fermentable by S. cerevisiae, and must be converted to ethanol by pentose fermenting yeasts or genetically engineered organisms.
Bioenergy crops
Bioenergy crops include fast growing trees such as hybrid poplar, black locust, willow, and silver maple in addition to annual crops such as corn, sweet sorghum, and perennial grasses such as switchgrass. Many other crops are possible, and much more information is available from the Oak Ridge National Laboratory the National Renewable Energy Laboratory, and various USDA regional laboratories. The optimal crop will vary with growing season and other environmental factors. Most fast-growing woody and annual crops are high in hemicellulosic sugars such as xylose.
Agricultural residues
Corn stalks and wheat straws are the two agricultural residues produced in the largest quantities, however, many other residues such as potato and beet waste may be prevalent in some regions. In addition to quantity it is necessary to consider density and water content (which may restrict the feasibility of transportation) and seasonality which may restrict the ability of the conversion plant to operate on a year-round basis. Facilities designed to use seasonal crops will need adequate storage space and should also be flexible enough to accommodate alternative feedstocks such as wood residues or other wastes in order to operate year-around. Some agricultural residues need to be left in the field in order to increase tilth and to reduce erosion. But some residues such as corncobs can be removed and converted without much difficultly.
Wood residues
Softwood residues are generally in high demand as feedstocks for paper production, but hardwood timber residues have less demand and fewer competing uses. In the past, as much as 50% of the tree was left on site at the time of harvest. Whole tree harvest systems for pulp chips recover a much larger fraction of the wood. Wood harvests for timber production often generates residues which may be left onthe site or recovered for pulp production. Economics of wood recovery depend greatly on accessibility and local demand. Underutilized wood species include Southern red oak, poplar, and various small diameter hardwood species. Unharvested dead and diseased trees can comprise a major resource in some regions. When such timber has accumulated in abundance, it comprises a fire hazard and must be removed. Such low grade wood generally has little value and is often removed by prescribed burns in order to reduce the risk of wildfires.
Waste streams
Numerous waste streams could be exploited for ethanol production. They are often inexpensive to obtain, and in many instances they have a negative value attributable to current disposal costs. Some principal waste streams currently under consideration include mixed paper from municipal solid waste, cellulosic fiber fines from recycled paper mills, baggasse from sugar manufacture, corn fiber, potato waste, and citrus waste, sulfite waste liquors and hydrolysis streams from fiber board manufacture. Each waste stream has its own unique characteristics, and they generally vary from one source or time to another. Waste streams with lower lignin contents and smaller particle sizes are easier to deal with than those with higher lignin contents and larger particle sizes. Waste paper that has been treated by a chemical pulping process is much more readily converted than is native wood or herbaceous residue.