The Next Generation of Biodiesel Coproduct Research
In the early days, the quality of crude glycerin produced at biodiesel plants was of little concern to biodiesel producers. “U.S. biodiesel producers were mainly interested only in the fuel aspect of the business and paid little attention to the byproducts they produced, even though crude glycerin production is 10 percent of the final product,” says Darol Brown, president of Portland, Ore.-based Sego International Inc. “Most did not pay attention to whether they could find a market for the glycerin, or what level of purity the market required. It was generally considered that a market for the crude would develop without their involvement, so they put no time or effort into understanding the total end result of the process.” Brown says in the 1990s, he was the largest importer of refined glycerin in the U.S. “What they needed to consider, and what they have now learned, is that the price they get for their byproducts helps offset their cost of production and profits,” he says. “Those who did not understand this have generally been bought out, or they have gone out of business.”
There are many grades of glycerin beyond crude, including technical- and pharmaceutical-grade (USP). USP Glycerin is 99 percent minimum with very tight limits on a multitude of potential contaminants, Brown says, and each shipment of USP requires a certificate of analysis. The applications for USP glycerin are endless. It’s used in an almost unlimited number of products. USP-grade glycerin is found in pharmaceuticals, food materials, nutraceuticals, cosmetics and personal care items. Some are less known applications, such as its use on raisins to keep them chewy, or as a cleanser for dairy cow udders to ward off infection.
There really is no set specification for crude glycerin, Brown says. “But each potential buyer has his own limits,” he explains. “Crude sellers must supply a lab test showing the assay of glycerin, the amount of methanol, ash, salts, and water and, in some cases, the amount of fatty acids. In general, unless you have changed the raw materials used, the plant will produce a consistent product and, if you know the producer, you can have some surety that the product will not vary, although most still require the test results to come with the shipment.” Some of the more common applications for crude glycerin include propylene glycol (anti-freeze), dust control and use an animal feed ingredient. “Crude glycerin is a cheap source of carbon and can be used in place of corn, grains or molasses in cattle feed, but it’s the lowest price and gives the least return to the producer,” Brown says. “Dust control is a major user of crude glycerin, but it is formulated with many other additives and is a rather cheap net back to the producer of the glycerin.” Brown says other applications are somewhat small and dependent on low-cost product.
“In the long term,” he says, “most glycerin should be refined to USP and sold into the high-end markets, and these refiners are starting to produce more refined product every day, but it does require a better quality of crude to make it feasible.” In the early days, biodiesel producers were producing low-quality crude with 35 to 60 percent glycerin content with high ash, methanol and fatty acid content, and while some producers today still produce similar low-value material, many plants have installed means to recover excess methanol and neutralize the caustic glycerin solution with acid to float out the fatty acids, which are suspended by the high pH of the reaction, and subsequently remove the ash and salts from the neutralization process. Water removal is also necessary to lower shipping costs.
Sego International’s crude glycerin spec calls for a minimum of 80 percent glycerin, less than 1 percent methanol, and no more than 3 percent inorganic salts, 18 percent water, 1 percent ash, 0.5 percent free fatty acids, 1 percent matter organic not glycerin (MONG), and a pH between 6 and 8.
The uses of glycerin—crude, USP-grade or otherwise—and other byproducts from biodiesel production are virtually limitless. Profiled here is the glycerin and coproduct research of three Next Generation Scientists for Biodiesel.
Karthik Gopalakrishnan is a doctoral student at the biosystems engineering department at Clemson University. Gopalakrishnan has been researching the use of crude glycerin as a carbon substrate to increase biomass and lipid production in the algae strain Chlorella protothecoides. “Glycerin is a three-carbon sugar alcohol that can be consumed by algae as a carbon source to produce oils,” he says. “The algae I grow in the lab produce about 60 percent oleic acid, which is an Omega-9 fatty acid.”
Gopalakrishnan says in autotrophy mode, carbon dioxide is a carbon source when coupled with sunlight or artificial light, and oxygen is produced in the process. “In the heterotrophy mode, organic carbon sources like glycerol and glucose can be used,” he says. “The presence of glycerin accelerates the growth of this algal species when compared to carbon dioxide alone.” In addition to crude glycerin, Gopalakrishnan provides other nutrients like yeast extract (a nitrogen source), some phosphate salts (a phosphorous source), vitamins and micronutrients. He says 1 gram of glycerol yields about 0.5 grams of algae containing 50 to 60 percent lipids.
“From my research, methanol has proven to decelerate the growth of the microalgae Chlorella protothecoides,” Gopalakrishnan says. “Other researchers have proved that Chlorella protothecoides has high salt tolerance, as high as 35 grams per liter, which can be equivalent to sea water.”
The goal of his research has been to increase biomass and lipid productivities, an important requisite for commercialization, and to do that, Gopalakrishnan built on previous research on the effect of the carbon/nitrogen ratio, which is “very important for lipid accumulation,” he says. “This was identified [by Yen-Hui Chen and Terry H. Walker at Clemson University] and I have used that in my research for improved biomass and lipid productivities.”
Gopalakrishnan has yet to work with commercial partners on his research, but says, “I would love to work with someone, to see my research into commercial production. Algae is the future of our lives, and I do envision algae biodiesel a reality in the future.” For this to happen, he says, focus must be put on furthering research and receiving government help in the form of grants.
Derek Pickett began as an undergraduate at University of Kansas in 2007 in the mechanical engineering program. Pickett recently earned his master’s degree with honors and is currently working at the university as a research scientist to improve a rig developed to gasify glycerin for combustion in a Chevrolet 350 V8 engine coupled with an electric generator. Pickett says the project was first developed by Bill Ayres from R3 Sciences LLC as a way to produce power from glycerin. The project was initially manufactured by the Biomass Energy Co. of Golden, Colo., and components of the initial rig were then donated to the University of Kansas in 2008 to get the system working repeatedly.
“The glycerin is converted to syngas through partial oxidation over a nickel catalyst on 22 millimeter aluminum oxide support spheres,” Pickett says. “The reformer catalytic material is first preheated with propane and once the appropriate temperature is reached, the glycerin is supplied.” At this point, the propane is shut off and the reaction continues without additional heat. “During both preheating with propane and the exothermic reaction of glycerin conversion, air is also supplied to control the temperature,” he says. The glycerin is broken down into hydrogen, carbon monoxide, methane, carbon dioxide and a few other trace species. Once the glycerin is converted to syngas in the reformer, Pickett says it is cooled in a heat exchanger, cooled again in an intercooler and then sent directly to the engine, which required only a few minor modifications to combust glycerin-derived syngas. “An aftermarket Woodward air-fuel valve and throttle valve were put on to allow for both pure propane and syngas combustion,” Pickett says. The exhaust gas recirculation (EGR) system was also disabled because the carbon dioxide and water vapor in the syngas act as EGR already.
The generator is a Mecc Alte ECO32-2L/4 alternator. “The power generation we were able to test was a function of our loading system, which was just simply two heavy-duty electric heaters drawing power from the generator,” Pickett says. They completed three loading tests: one with no heaters applied, then one heater (3.6 kW) and then two heaters (6.5 kW). With additional loading capabilities such as more, or larger, heaters, Pickett says the generator is capable of producing 50 kW.
They were able to run the engine at 1,800 RPMs and no load using about four gallons of glycerin per hour. “By increasing the flow rate of glycerin to approximately 4.8 gallons per hour, we can achieve 3.6 kW,” Pickett says, “and at 5.5 gallons per hour we achieve 6.5 kW.” He says the glycerin flow and power output trend is very linear, and to achieve the 50 kW max output of the generator, Pickett estimates it would require glycerin at a flow rate around 15 gallons per hour.
So far, two different types of glycerin have been tested, according to Pickett—food-grade, and refined glycerin from Renewable Energy Group Inc. “The only effect the purity has is on required flow rates of glycerin,” Pickett says. “When using the lower-quality glycerin, a higher flow rate to the reformer was required in order to produce the appropriate syngas.” He says future work will include trying to achieve syngas production from crude glycerin. A significant amount of heat loss, mostly from the engine, leaves room for future work on heat recovery and reuse for feedstock processing, distillation or use in an Organic Rankine cycle. “Using this technique, the heat could be used to produce useful work that could then be used to produce more power for the system,” he says.
The main goal of the system is to couple the rig with the initial production of biodiesel. Once more research is completed with the system and upgrades are made, the rig could potentially use the glycerin byproduct from the initial production of biodiesel for power generation. He says the most important finding is that the overall system is possible. “As far as I know, this is a very unique setup that no other university or company has attempted. Using glycerin for hydrogen-rich syngas production has been completed but utilizing the syngas for combustion and power generation has not been done. Additionally, once the rig is capable of operating directly with the initial production of biodiesel, there will be many commercial applications for the process.”
Scaling up the system will increase the efficiency of the entire rig, Pickett says. “The Chevy 350 V8 is probably too large for the reformer we have in place, because a significant portion of the glycerin is just used to run the engine at idle.” The Kansas Soybean Commission and Renewable Solutions LLC provided significant funding for this project.
Michael Morgan, an undergraduate at Utah State University, began working as a research assistant, in 2009, with the USU team on biofuels projects under the mechanical engineering program, but after becoming deeply interested in lipid technologies he switched his major to biochemistry. Now he is based in the biochemistry lab of professor Lance Seefeldt.
USU began researching algae production in 2007. “In 2011, we began working with other oleaginous, or lipid-producing, microbes including yeast and bacteria, and we have been able to grow these organisms on carbon-rich, low-value effluent to create higher-value compounds such as biodiesel,” Morgan says. The team successfully created and patented a direct in-situ transesterification biomass conversion, which allows conversion of all available lipids from the biomass without doing an initial neutral lipid extraction from the microbial sources. He and the microbial products team successfully created biodiesel from yeast, microalgae and bacteria to do engine testing for performance and exhaust emission characteristics, the results from which have been published in Energy & Fuels.
Morgan set up a dynamometer and emissions station for testing the performance and emissions characteristics of each of the three microbial biodiesel types, for comparison to soybean biodiesel and No. 2 petroleum diesel. The team also built a diesel streamliner fueled by biodiesel from algae, bacteria and yeast and raced it on the Bonneville Salt Flats three times, setting one record and beating two current records. Morgan was lucky enough to drive the racecar during one of those timed events and produce the yeast and algae biodiesel used at the famed race spot in 2012 and 2013.
“For our yeast and bacterial growths we utilize 10-liter and 100-liter fermenters, and will soon be utilizing a 500-liter fermenter,” Morgan says. “We are interested in producing high-value coproducts as part of our biodiesel production program in order to help the cost-effectiveness of biodiesel production,” which could open new funding opportunities and collaborations. “We are looking at the different biomass profiles of each of the yeast strains used in our lab,” Morgan says. “Each organism has a unique profile for proteins and lipids especially,” he says. “As biochemists, we are working to understand the sequestration pathways and the profiles of the final products so that we can best determine optimal usage for each organism in the creation of bioproducts. We are in the process of working with an industry partner to optimize protein production from a few of our yeast strains and are also using genetics to produce specific desired products that have higher value.” He says the USU-created techniques used for extraction/conversion for biodiesel creation also allow them to maintain the yeast proteins for processing into coproducts. “This allows us the benefit of having multiple end products, which increases our ability to become economically viable in creating biodiesel using microbial sources,” Morgan tells Biodiesel Magazine. “For the production of lubricants, we are partnering with other outside entities that have unique chemical processes that create or eliminate compounds that cause biodiesel to have lower energy content and reduced long-term storage ability,” specifically the removal of carbonyl groups, he says. “Each of the coproducts that we are working toward have the goal of creating valuable compounds and reducing necessary processing in an effort to create an economically sustainable microbial biodiesel and bioproducts model that can be taken to industry.”
The USU team began looking into coproducts once the ability to produce sufficient quantities of biomass and FAME that analysis could be conducted on the value of the final products versus production costs. “It became apparent, especially in the case of microalgae, that we were not yet close to being economically sustainable,” Morgan says. Most of the coproduct work at USU has focused on yeast. “I believe without strong coproduct utilization and research into improving the value of the derived coproducts, the advanced biodiesel production initiatives will struggle to be funded and become or remain profitable,” Morgan says. Due to USU’s use of microbial sources for all of the university’s biodiesel production, the team has been involved only on a limited basis so far into biodiesel coproduct determination. “For the most part, our look at coproducts have mainly come through results in the lab and finding the value of the products that are naturally occurring in the strains we have selected over the past seven years, and utilizing our technologies that we have developed,” Morgan says. “The methods that we use for our conversion have helped lead us to the breakthroughs that we’ve had here in the lab and approach companies that may be interested in our results. This is why we have been working mainly with proteins and recently some lubricants. We are blazing new frontiers here in our lab due to our choice of microbial strains for biodiesel and bioproduct creation and, as such, are helping to develop new markets or enter existing markets with an alternative product source.”
Author: Ron Kotrba
Editor, Biodiesel Magazine