Commercial Projects
Reactor Design: North Mississippi Biodiesel, Inc.
Methanogenic Conversion of the Biodiesel Byproduct: Glycerol
Reactor Design: North Mississippi Biodiesel, Inc.
The primary goal of this project is to evaluate the effectiveness of a custom designed reactor vessel for the production of biodiesel from soy bean oil. Investigations will occur on site in Union County, Mississippi. We propose to design and construct a reactor vessel on site as a component part of the production process to produce biodiesel fuel. While "biodiesel" is not new, the manufacture in commercial quantities is growing exponentially. Evaluating the success of the design is accomplished in evaluating the product produced.
The custom design of process equipment is cost effective and provides skilled construction jobs in the community. Purchasing general stock equipment out of state moves much of the initial financial benefit to the community out of state. We propose that many of the process components can be designed and constructed by local skilled labor, utilizing materials available from local vendors. We propose to build the largest single component for the entire process on site resulting in significant savings to us_ Income in the community is benefited in this manner. Skilled construction jobs typically have greater payroll per individual compared to unskilled labor. Further, biodiesel in the marketplace provides a cost saving alternative to imported and domestic petroleum products. The niche consumer gets a good value when choosing biodiesel, engines will last longer... Tax revenues are generated in construction (sales tax) as well as production through sales to vendors and subsequent highway use taxes. Mississippi's rural economy will benefit from increased marked interest in local family farming of soybeans as a "cash crop" with a future. The interest and promotion of soy biodiesel is largely the result of promotion by soybean farmers and marketers. Ag interests in Mississppi are keenly aware of the merits of the product.
Technical obstacles of this project are the high start-up costs of building a manufacturing facility , particularly in Mississippi. Most of the commercially available components are manufactured out of state, and are expensive, as custom orders, and incur delays in shipping with associated costs. Technical components made out of the country may be a matter of months before delivery. "Making biodiesel" chemically is a relatively simple process, however producing it commercially in sufficient quantities is another consideration. While the chemistry is "the same" many facilities, each by design is a unique production process and there is no "industry standard" at this time. Of producers across the United States, there is a wide variation of production volumes and feedstocks. There are many routes to an end product called biodiesel, but the most popular is through use of soy bean oil. Reducing start-up costs would likely facilitate greater investment in a new commercial venture.
The specific innovation to be tested in this project is a custom reactor design that is simple, yet adaptable to a variety of batch process production requirements. The reactor could be built on site utilizing local skilled labor and a minimum of specialized equipment. Reactors are sized to meet productions objectives of the facility. Assessment of reactor effectiveness is demonstrated by the production of biofuel meeting all production industry standards for biodiesel. Testing on fuel would be conducted at private regional labs as well as at Mississippi State University. Fuel meeting all applicable industry standards would be a reliable indication of reactor design suitability.
Primary task is to construct a reactor vessel for the mixing of soy bean oil and methoxide at normal pressure at required process temperature and in sufficient quantity to provide for reliable commercial production. Construction on site is desirable to meet custom specifications and process needs. While the reliability of the design is measured by the quality of the fuel produced, the greater innovation is to foster development of an industry in the state and nation that will surely reduce our dependence on foreign oil. Components for commercial biodiesel facilities are not readily available as such in the United States, however skilled assembly of available "parts from other industrial processes" can result in a satisfactory production process. Based on our research, many critical components in a biodiesel plant, were designed and built to serve other purposes prior to their production "life" in a biodiesel facility. A factory made component built in Europe will surely add to increased start-up costs.
We intend to introduce our finished product B100 biodiesel in the south eastern U.S. particularly in North East Mississippi through our marketing alliance with a regional petroleum distributor, established in the same community. We expect our product to be available regionally through this distributor in B20 (20%) blends at a price advantage to the consumer. This fuel has been well received in this market area, although production and availability from others prior was sporadic and unreliable. Construction of this specific facility addresses those earlier issues and expands to meet future production needs. Our distributor has made a written-commitment to buy our entire production. At this time the name of our distributor is confidential.
The North Mississippi BioDiesel, Inc. site is located in Union county, in close proximity to our primary distributor, and "on the way" to Memphis to the regional source for petroleum bulk distribution. In addition to on site storage, filtration equipment is necessary to refine the biodiesel and insure that it meets industry standards. We have currently 250,000 gallons of storage on site. The raw oil tanks are preheated. Each of the reactors will be heated.. Filtration of the biodiesel will include "dry washing" with Magnasol and filtering through a filter press. Our process area utilizes 12 large pumps for various purposes transferring liquids. We can receive and distribute materials from this site by highway, or by railroad with our spur on Miss.-Tenn. Railroad. The entire process area meets spill containment requirements and is linked by a common vapor recovery system to limit process emissions. We have addressed all state and federal permitting requirements and are authorized to begin initial production in March 2006.
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Methanogenic Conversion of the Biodiesel Byproduct: Glycerol
Biodiesel is considered a displacement alternative to petroleum diesel. It is produced via reacting plant oils and/or animal fats with an alcohol (traditionally methanol) and a catalyst (traditionally sodium hydroxide). The chemical reaction is illustrated in Figure 1 of the appendix. The products of the reaction are fatty acids methyl esters (biodiesel) and glycerol. The biodiesel can be utilized in its neat form or blended with petroleum diesel as fuel in a compression combustion engine. In the past, glycerol, in its refined form, was sold on the open market for approximately $0.80 per pound. Different industries use the refined glycerol in variety of products such as food, pharmaceuticals, cosmetics, etc.
High petroleum prices and tax incentives for biodiesel has caused a significant increase in biodiesel and glycerol production over the last two years. This increase in glycerol production has had tremendous impacts on current market prices. In the past year alone refined glycerol prices have dropped from $0.35 per lb to $0.16 per lb suggesting glycerol supply has surpassed the current markets need for this versatile chemical. Inventories of this compound are reaching crisis levels at many biodiesel facilities. In recent months, some Mississippi biodiesel producers have had substantial difficulty marketing their glycerol by-product. What was once a profitable byproduct has now become a liability. Since the traditional markets are currently unavailable, new dependable markets and/or long term uses must be identified for glycerol. An economically and energy efficient option for the biodiesel producer would be the conversion of glycerol a commercially established fuel.
In addition to the numerous commercial uses, glycerol is also a very important biological molecule. Glycerol is a metabolic intermediate during the breakdown of most sugars that can be used by cells to create energy or products. Of importance here is the ability of some microorganisms to convert glycerol to methane. When oxygen is limited a consortium of microorganisms known as acetogens and methanogens enzymatically convert glycerol to methane. This is accomplished through a synergistic relationships formed between these groups of microorganisms. The process works when acetogens first convert the glycerol to acetic acid followed by the conversion of the acetic acid to methane by methanogens. This methane could provide the energy to generate steam needed during the processing of vegetable oils to biodiesel. Traditionally, natural gas is used as the fuel for the generation of steam but natural gas prices have soared from $10.00 thousand cubic feet (tcf) to $14.00 tcf in the past year alone with price predicted to go even higher. This is a significant cost to the biodiesel producer that is further compounded by the loss of revenue from the sale of glycerol. Therefore, the overall objective of this proposal is to design and optimize a system to digest the glycerol generated during biodiesel production into methane using a consortium of acetogens and methanogens.
Generation of biogas is a well-established technology especially for the conversion of animal manures on a relatively large scale. The science of acetogenis and methanogensis is very well understood (Drake 1994). Metabolic pathways have been identified for both acetic acid production and methane generation. However, little work has been done on the development of technologies to take advantage of these microorganisms abilities on the scale required for a biodiesel producer or the utilization of glycerol as the sole carbon source for the production of methane. It is known that the acetogen, A. carbinolicurn, has the ability to produce acetic acid and water from glycerol and carbon dioxide as shown in Formula 1 (Drake 1994). The actual biological conversion of glycerol to acetic is a bit more complex than that shown in Formula I and is given in more detail in Figure 2. This is one of the critical steps in the production of methane by methanogens. Aceticlastic methanogens are one of the largest subgroups of methanogens know to exist and they require acetic acid for the production of methane. They make their living through the conversion of acetic acid to methane and carbon dioxide as shown in Formula 2. Methanogens also can produce methane from a variety of other carbon sources such as CO2, formate, methanol, and other unidentified compounds (Ferry 1992 and Lou, et al. 2002).
4C3H803+2CO2 -* 7C2H402+2H20 (I)
C2H402-* CH4 + CO2 (2)
Highly efficient digestors must provide this consortium of acetogens and methanogens with the required nutrients. Aceticlastic methanogens have some important coenzymes and cofactors associated with this pathway. The first coenzyme utilized in the pathway is coenzyme A (CoA), which is followed by the transfer of the methyl group to tetrahydrosarcinapterin (H4SPT) with the concomitant evolution of a CO2 molecule. The methyl group attached to the H4SPT is transferred to S-CoM. Fortunately, these coenzymes are synthesized by the methanogens themselves. On the other hand there are nutrients that must be supplied to ensure proper conversion of the glycerol to methane. The cofactors essential to this pathway are nickel and iron (Ni/Fe-S) and cobalt. The Ni/Fe-S is believed to be the site that the carbon-to-carbon bond in the acetic acid molecule is cleaved resulting in the production of CH3 and CO2 (Muller 2003). The cobalt facilitates the transfer of the CH3 from the NI/Fe-S to the S-CoM. This has been well studied in Methanosarcina barkeri (Muller 2003). As result of this work and many others, the nutritional requirements of these organisms are very well understood and can be provided through the addition of inorganic minerals.
Besides the nutritional requirements of methanogens, there are numerous physical and chemical factors that directly or indirectly affect efficiency of methanogenesis. These factors include temperature, pH, inorganic nutrients,organic carbon availability, and reduction/oxidation potential. In traditional digestors where the organic inputs are much more complex than glycerol, there exist the potential for undesirable groups of microorganisms to proliferate. When protienacious organics like manure are added to a digestor, compounds such as NO3, Mn, Fe, or SO4 are introduced and provide the opportunity for different groups of microorganisms to predominate over the methanogens (Prescott et al. 2001). This would result in a loss of methane production. The envisioned system would have the ability to prevent this scenario from occurring. Crude glycerol contains little to no NO3, Mn, Fe, or SO4 and would therefore not be introduced into the digestor. The redox potential is another environmental factor that has an impact on methane production. For maximum methane generation, the redox potential must be below -200 mV (Drake 1994). Within a small-scale digestor this can be easily controlled. With consortiums temperature shifts can determine what species of methanogen will dominate. Chin et al. showed that Methanosaeta sp. predominated over Methanosarcina sp. when the temperature was reduced from 30 C to 15 C (1999). Temperature is another environmental factor that can be easily manipulated on the small scale. The temperature and redox potential that yields the highest conversion of glycerol to methane needs to be determined. Until recently, conventional wisdom believed that methanogenesis did not occur at pH values much below 6.5. This thinking has since been proven wrong. Horn et al. showed that pH below 5.00 resulted in predomination of autotrophic methanogens (this a subgroup of methanogens that convert CO2 and H2 to methane) over acetoclastic methanogens. Resent work presented by Taconi et al. at the 2003 American Institute of Chemical Engineers Annual Meeting showed that environments with pH values above 5.0 the CO2 is in the form of a carbonate and was not available by her consortium of methanogens. However, when she conducted similar experiments at pH 4.5 the CO2 remained as CO2 and was converted into CH4, thus supporting the results observed by others.
Although the generation of methane from biomass is a well-defined science there needs to be some optimization for the utilization of the glycerol stream generated during biodiesel production. The technical challenge for this technology is to identify the optimum redox potential, temperature, and pH-for the conversion of glycerol to methane.
Project Objectives: The main objective of this investigation is to develop a process that utilizes microorganisms to convert crude glycerol generated during biodiesel production to methane. Other secondary objectives include:
1. Determine the optimum nutrient formulation for the conversion of glycerol to methane.
2. Determine the optimum temperature and pH for methane generation.
3. Optimize methane generation using crude glycerol.
4. Demonstrate a pilot unit generating methane using the crude glycerol produced by a Mississippi biodiesel producer.