Evolving Biofuels Require New TestsSecond-generation feedstocks require modified test protocols from those developed for first-generation biofuelsby Tim Studt
Metrohm’s 873 Rancimat method mimics the oxidation of a biodiesel sample at a fixed temperature with extrapolated results to the oxidation stability under real-world conditions. | First-generation biofuels are maturing with production in excess of 100 million liters/day and with instrumentation and testing methodologies established for a few simple ethanol-blended gasoline and biodiesel products. But the economics of using these materials cannot survive. The costs to produce them—mostly corn-based ethanol in the U.S.—is currently close to the cost that a gallon of ethanol-blended gasoline sells for at the pump. Biofuels were considered economically viable alternative fuels when crude oil stocks were at $70/barrel, but with the current depressed crude oil prices, this is no longer the case. Current biofuel feedstocks also are a primary global foodstock and export tradestock, which has raised foodstock costs while limiting its availability.A plethora of second-generation biofuel feedstocks are being evaluated that are expected to increase energy efficiency and lower costs, and they are non-foodstocks. These proposed lignocellulosic-based energy crops include woody plants and perennial grasses. They typically sequester carbon as they improve soil quality, require few fertilizers or pesticides, and don’t have to be grown on agricultural land that could be utilized for food production. The recent "90-Billion Gallon Biofuel Deployment Study" by researchers at Sandia National Laboratories, Livermore, Calif., and General Motors Corp. assessed how large a volume of lignocellulosic biofuels could be sustainably produced. The study revealed that plant, forestry waste, and second-generation dedicated energy crops could sustainably replace nearly a third of gasoline use by 2030.
Dept. of Energy - Energy Frontier Research Centers (EFRCs) www.sc.doe.gov/bes/EFRC.html |
• Rational Design of Innovative Catalytic Technologies for Biomass Derivative Utilization, Univ. of Delaware, Dionisios Vlachos, Director
• Center for Direct Catalytic Conversion of Biomass to Biofuels (C3Bio), Purdue Univ., Maureen McCann, Director
• Center for Advanced Biofuels Systems (CABS), Donald Danforth Plant Science Center, Richard Sayre, Director |
• Photosynthetic Antenna Research Center (PARC), Washington Univ., Robert Blankenship, Director
• Center for Lignocellulose Structure and Function, Pennsylvania State Univ., Daniel Cosgrove, Director
• Energy Biosciences Institute, www.energybiosciencesinstitute.org
- Univ. of California, Berkeley
- Univ. of Illinois, Urbana-
Champaign
- Lawrence Berkeley National
Laboratory
- BP U.S., Houston, Texas | Most biofuels are produced by straightforward and established manufacturing processes, are relatively biodegradable and non-toxic, have low emissions profiles, and can be used as is (biodiesel) or blended with conventional fuels (ethanol).Ethanol-based biofuels have become predominant in the U.S., while biodiesel is the more dominant biofuel in Europe. Bioethanol is mostly used as a blend with gasoline. Biodiesel can be used as a 100% replacement for diesel or as a blend with diesel. "Current biofuels are very regulated (to U.S. ASTM, European EN, and Brazilian NBR and ABNT standards)," says Peter Hoedl, director, Renewable Energy, PerkinElmer. "There are relatively few issues with the current technologies. Each region has its own standards." Instrumentation workhorses
The unique dual oven on PerkinElmer’s Clarus 500 GC allows it to complete both biodiesel glycerin and methanol GC analyses on a single instrument.
| Gas chromatography is the workhorse for biofuel analyses such as those for iodine number, fatty acid methyl ester (FAME) content, linolenic acid methyl ester (LAME) content, polyunsaturated methyl esters content, methanol content, and monoglycerine, diglycerine, triglycerine, free glycerine and total glycerine contents. Differential scanning calorimetry (DSC) is used for oxidative stability, and infrared (IR) spectrometry is used for FAME blends while ICP (inductively coupled plasma) spectrometry is used for measuring trace metal contents, like sodium and potassium. Metrohm offers ion chromatographic techniques for determining glycerol and antioxidants in biodiesel and the chloride and sulfate contents in bioethanol. Metrohm also has a potentiometric acid-base titration technique for determining the acid number in biodiesel."Atmospheric GC systems are also staging a comeback in the analysis of biofuels" says Alice DiGioia, senior manager for Chemical Analysis at Waters Corp. "Oxidation in biodiesel products is also a concern with traditional tests often measured in hours or even days. Testing these properties in an UPLC can accelerate that test time to just minutes."
Much of the instrumentation will remain the same for analyzing second-generation biofuel feedstocks. "But current methods are lagging, especially for the development of second-generation biodiesel feedstocks," says Jim McCurry, senior applications chemist at Agilent Technologies. "It has become difficult to measure naturally occurring contaminants in some new biodiesel feedstocks. These contaminants are mostly non-volatiles and cannot be measured by standard gas chromatography (GC) techniques." Sterols, one of these contaminants, can cause problems in the normal processing of biodiesel feedstocks. Waters’ DiGioia agrees that the measurement of impurities in biofuels has become a concern for researchers. McCurry also notes that measuring some biofuels, like pure ethanol with a denaturant added for transportation purposes (to avoid shipping a drinkable alcoholic liquid) can be difficult with conventional instrumentation. Second-generation limitationsWhile there are numerous specifications developed for first-generation biofuels, there are no specs developed for the second-generation materials because they’re still in the R&D stage. "In Malyasia, for example, their second-generation biofuel feedstock had an interference with the method which gave the wrong result," says McCurry. Most manufacturers have developed suites of columns for the available GC systems that have been tested and branded. The manufacturers are still attempting to evolve their designs for second- and third-generation feedstocks. Third-generaton biofuels are those with genetically altered first- or second-generation feedstocks or algae-based materials. "The potential yields being talked about for algae-based biofuels are very interesting," says PerkinElmer’s Peter Hoedl.
Net Energy Balance |
Product |
Energy out/Energy in |
Gasoline |
0.81 |
Ethanol from grain |
1.30* |
Ethanol from grain |
1.67** |
Ethanol from cellulose |
2.00*** |
Petroleum diesel |
0.83 |
Biodiesel |
3.20 |
Source: Congressional Research Service |
* Current technology
** Optimum technology
*** Conservative estimate | A number of biomass materials are being evaluated for selection as the optimal second-generation biofuel feedstock. While corn, sugar beets, sugarcane and palm oil (biodiesel) have been the primary first-generation feedstocks, second-generation potential feedstocks include canola, camelina, jatropha, salicoma, duckweed, Agave, poplar trees, switchgrass, eucalypts, miscanthus, sorphum, willows and others.These second-generation, lignocellulosic feedstocks offer a more abundant, underutilized resource. Producers can often process co-products or use crop residues, along with dedicated energy crops. The added complexity of these cellulosic materials is that a pretreatment process is needed, as well as new enzyme systems, and the development of
5-carbon sugar fermentation processes. Sky Countryman, manager of product management and applied technology at Phenomenex, notes that the development of second-generation biofuel feedstocks is likely to evolve to regional selections. "Since the transportation costs of materials is such a significant part of the overall cost, there’s likely to be regional processing plants with regional feedstocks that are naturally friendly for that particular region," he says. Countryman also notes that for second-generation biofuel feedstocks, "you’re going to need to do more in sample preparation steps prior to testing the materials, especially for bioethanol where the fermentation step may be analyzed with HPLC systems." Many of the steps for second-generation feedstock analyses will still utilize the same GC, IR, and DSC instruments, but the specific test protocols will just be more complex. The samples and the compounds will be different; the impurities will have to be scrubbed, and there will be different stationary phases and specialized detectors. "Also, in order to create a more efficient and cost-effective process, second-generation biofuels will require manufacturers to utilize online process analyzers in the field," Countryman says. He also notes that his company’s Zebron Zb-5HT Inferno GC columns have been developed for the evolving testing of glycerin in biodiesel feedstocks. The higher temperature gives better column lifetimes and allows optimized formats for faster cycle times. Third-generation research
Waters’ ACQUITY UPLC paired with the Xevo QTof mass spectrometer is suited for the analysis of biodiesel and organic contaminants.
| Genetic modification of second-generation biofuel feedstocks is expected to enhance the yield of these plants, along with hopefully focusing production on a narrow plant species, with the resultant increase in economies of scale. A number of research programs are underway, including one at Brookhaven National Lab where researchers are modifying high-yield woody plant cells to make them more digestible.Development of algae-based biofuels is also proceeding with the recent opening of a small pilot plant by Stellarwind Bio Energy in Indianapolis. Unlike corn, which produces 550 to 1,250 liters of ethanol/acre/year, algae can produce nearly 40,000 liters of biofuel/acre/year. Also, the oil produced is superior to bioethanol or biodiesel in that it can be sent directly to a refinery for conversion into gasoline. For more information, contact:
Sky Countryman, Mgr. Product Mgmt. & Applied Technology, Phenomenex, skyc@phenomenex.com
Peter Hoedl, Dir. Renewable Energy, PerkinElmer, peter.hoedl@perkinelmer.com
Christy Hurles, Project Mgr., Metrohm USA, churles@metrohmusa.com
James McCurry, Sr. Applications Chemist, Agilent, james_mccurry@agilent.com
Jim Mott, Sr. Technical Support Specialist, Shimadzu, jamott@shimadzu.com
Brian Murphy, PR, Waters Corp., brian_j_murphy@waters.com
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