Journal American Society of Sugar Cane Technologists, Vol. 30, 2010

Transcription

1 Economic Feasibility of Growing Sugarcane and Energycane for Energy on the Mineral Soils of Southern Florida J. Álvarez 1, Z.R. Helsel 1, L.E. Baucum 2, R.W. Rice 3, and R.A. Gilbert 1 1 Everglades Research and Education Center, University of Florida, Belle Glade, FL 2 University of Florida, Hendry County Cooperative Extension Service, LaBelle, FL 3 University of Florida, Palm Beach County Cooperative Extension Service, Belle Glade, FL Florida has caught the attention of several firms that have developed technologies to convert crops into energy. The University of Florida s Institute of Food and Agricultural Sciences is currently involved in a multitude of research projects in this area. This paper reports a preliminary economic assessment of agronomic research conducted on sugarcane and energycanes on mineral soils in southern Florida. Agronomic data were incorporated into an enterprise budget format. Results were obtained from sugarcane and energycane grown as energy crops. The budgets address the typical cost and return figures, break-even outcomes, and are used to perform sensitivity analyses at different levels of yields and prices of ethanol. Under the assumptions of this study, including the cost and price structure expressed in nominal values, results indicate that, at current average yields of sugarcane of 32 tons/acre in a 4-year cycle, the break-even price of ethanol would be about $1.57/gallon, not including the costs of processing, fermentation and distillation. For a 6-year cycle of energycane with an average yield of 30 tons/acre, the break-even price of ethanol excluding the costs of processing, fermentation and distillation would be around $1.15/gallon. Although no definitive recommendations can be extended at this stage, most scenarios analyzed appear to indicate that the potential of sugarcane and energycanes as biofuel crops will largely depend on fermentable biomass yields, prices of fertilizer and chemical inputs, and distance from the fields to the processing plant. Comparative Study of Multiple Energy Crops for Cellulosic-Ethanol Production M. Kim and D.F. Day Bagasse from energy crops such as sugar cane and energy cane were used to produce cellulosic ethanol. Chemical compositions were 41% cellulose, 25% hemicellulose, 21% lignin for commercial sugarcane and 54% cellulose, 29% hemicellulose and 21% lignin for energy cane. Lime treatment was performed with a mixture of bagasse, calcium hydroxide and water at a ratio of 1:0.2:8 at 121⁰C for 1h. The treatment retained most of cellulose for both energy crops and removed 57% of lignin for commercial sugarcane and 47% of lignin for energy cane. When both energy crops were hydrolyzed with a mixture of cellulases such as Spezyme CP and Novozyme 188, theoretical cellulose hydrolysis 156

2 yields were 85% for treated commercial sugarcane bagasse and 72% for treated energy cane bagasse. After both energy crops were fermented by Saccharomyces cerevisiae, ethanol concentrations were 0.20 g/g dry biomass for treated sugar cane bagasse and 0.15 g/g dry biomass for treated energy cane bagasse. Biodiesel from Algae as an Alternative for Sugar Mill Sustainability V. Kochergin 1 and M. Suhr 2 1, LSU AgCenter, St.Gabriel, LA 2 MS Processes International, Hutchinson, MN Sugar industry needs innovative approaches for improving its sustainability. Emerging biorefining industry appears to be a natural partner for the sugar mills that offer possibilities of integration of new technologies into existing processing facilities. Algae production has been considered as a promising source of biomass for conversion into fuels and added value chemicals. Some strains of algae containing % oil show promise of productivity of times higher compared to oil producing land crops. Sugar cane mills can supply carbon dioxide from flue gas necessary for algal growth and can provide electric power and steam required for biomass conversion. Additionally, cane mills generate significant amounts of clean water and have ponds available for algal production. Material and heat balances have been evaluated for an operation scenario, where algae are produced next to a 15,000 tpd sugar mill providing energy for algae cultivation, harvesting, biomass drying, oil recovery and biodiesel conversion. Assuming algal biomass production rate of ton/acre/day and 30 % oil content in algae, sugar cane mill can support a 10,000,000 gallon/year biodiesel production facility. The amounts of produced biodiesel well exceed the fuel requirements for cane harvesting and transportation. Co-location of a sugar cane mill and algal facility allows taking advantage of existing agricultural infrastructure and resources while maintaining the same level of sugar production. 157

3 Recent Developments in Sugarcane Agriculture that Affect Processing B. L. Legendre Louisiana State University Agricultural Center, U.S.A. Sugar yield and sugar quality are affected by the quality of the product being processed. Sugarcane quality and sugar yield and quality are interrelated. In many production systems, both agricultural and manufacturing, there is conflict between productivity in the field and sugar quality. High productivity and/or throughput many times compete with high product quality. However, sugar quality can be influenced by ever-changing developments in sugarcane agriculture including the basis on which the cane is purchased by the factory, the introduction of new cultivars, use of chemical ripeners, changes in cultural practices and harvesting systems and the introduction into an industry of new disease, insect and weed pests. These developments differentially impact cane and juice quality and have a direct bearing on processing and, ultimately, sugar quality. Further, cane and sugar quality have taken on new meaning today with the vertical integration of many sugar operations from field to refinery to consumer. Today s refiners are seeking very high pol (VHP) sugar (>99.2 pol) and very low color (VLC) sugar (<2200 ICUMSA units). Therefore, it becomes imperative that we start with high quality sugarcane from the field if we are to produce high quality sugar for the refinery. Entrainment Losses in Louisiana Sugar Factories H. Birkett and J. Stein Sugar concentrations in evaporator condensates and in the barometric condenser water were measured at 10 Louisiana factories in 2009 using the phenol-sulfuric acid method. The concentration of sugar varied from 2 to 1650 ppm in evaporator condensates and represented an average sugar loss of 0.13 lb/ton at the average concentration of 89 ppm. In the case of the condenser water, once through injection water systems had sugar concentrations of 1 to 857 ppm with an average of 180 ppm which represented an average sugar loss of 1.8 lb sugar/ton cane. For recirculating injection water systems (cooling towers and spray ponds) the sugar concentration in the injection water varied from 1000 to 7000 ppm. Assuming a blowdown rate of 2%, the losses in the recirculating systems averaged 1.8 lb sugar/ton cane. The paper highlights the need for frequent testing of both condensate and condenser water streams to minimize sugar losses. 158

4 New Approach to Fluid Distribution in the Industrial Clarifiers V. Kochergin and C.Gaudet, LSU AgCenter, St.Gabriel, LA Juice clarification in a traditional cane mill is the only unit operation where suspended solids are separated before sugar boiling. Although residual solid content in clarified juice is typically less than a ppm, it is often a result of the increased residence time (1-1.5 hours), which results in sucrose losses. Clarification process is especially important for Louisiana sugar mills due to the climatic conditions and the type of soil that lead to elevated mud levels. Computerized fluid dynamics simulations performed by various research groups illustrate presence of turbulent eddies in the clarifiers that are responsible for efficiency reduction. Turbulence is highly influenced by the uniformity of juice introduction into a clarifier. A new design of a single tray juice clarifier has been tested in a Louisiana sugar mill during the 2009 season. A simple juice distribution system comprises a number of feed pipes uniformly distributed over the vessel crosssection. The end pieces of the pipes are supplied with turbulence reduction devices that virtually eliminate momentum of the feed juice. Comparison of clarified juice turbidity indicated that new design outperformed existing Dorr and Graver designs that were operated in parallel in the same plant. Operating results will be discussed as well as optimization challenges. Iron Mediated Clarification and Decolorization of Sugar Cane Juice: A Pilot Test L. R. Madsen and D.F. Day Research and development of a system which removed 50-60% of the color from cane juice (relative to hot-limed juice) was completed in The ASI pilot-scale settling clarifier was modified to accommodate sequential dosage of chemicals (ferric chloride and cationic polyacrylamide) prior to liming to ph The limed juice was then heated to flash and anionic polyacrylamide was added directly to the flash tank. The resulting juice was settled normally, and the color was compared to both a cold-limed control and the clarified juice made by the mill. When tested at the Westfield Sugar Factory, the process produced a clarified juice with 45-50% less color. This method is discussed in terms of chemical cost (relative to potential premium for low color) and the potential for color reduction, full-scale, in the raw sugar mill. Sugarcane Yield Monitors R. R. Price 1, R. Johnson 2, and R. Viator 2 159

5 1 Biological and Agricultural Engineering Department, Kansas State University, Manhattan, KS USDA, ARS, Sugarcane Research Laboratory, Houma, LA One of the keys to successful precision agricultural systems is a yield monitor. Several yield monitoring systems were tested to indicate cane yield with a specific goal of monitoring truck load out weight information from the cab of the chopper harvester. The most developed system, an optic approach with three under-conveyer fiber optics and self-cleaning abilities, demonstrated a zero intercept linear line with an R-square prediction of The average overall prediction error on small loads (0.5 to 1.6 metric tons) was 7.5% while the average predicted error on commercial loads (21 metric tons) was 2.5% with a standard deviation of Factor testing indicated that the duty cycle reading was not affected by cane variety, harvester speed, harvested distance, or direction of cut (lay of the cane). Several other approaches are currently being evaluated to decrease errors on truck load weight predictions to below 2% with minimal calibration. Biomass Yields and Fiber Concentration of Energycane and Giant Reed Grown on Sandy Soils in Florida P.H. Korndorfer 1, R.A. Gilbert 1, Z.R. Helsel 2, J. E. Erickson 3, and L.E. Sollenberger 3 1 Everglades Research and Education Center, University of Florida, Belle Glade, Fl 2 Department of Biology and Pathology, Rutgers University, New Brunswick, NJ 3 Agronomy Department, University of Florida, Gainesville, Fl The development of carbon-neutral energy sources has become one of the primary challenges of the twenty-first century. Perennial grasses such as energycane (crosses of commercial sugarcane (Saccharum spp.) with S. spontaneum) and giant reed (Arundo donax L.), have been proposed as feedstocks for lignocellulosic ethanol or direct combustion. The objectives of this study were to evaluate biomass yields and fiber concentration (cellulose, hemicellulose, and lignin) of energycane genotypes and giant reed in nutrient-poor sandy soils of south Florida. Eight energycane genotypes (875-3, US , US , US , US , US , US , US ) and giant reed were compared in a randomized complete block design at two sandy soil locations in south Florida (Tecan, Florida Crystals Corporation, and Townsite, United States Sugar Corporation) from 2008 to At Tecan, fresh weight yields of all energycane genotypes ranged from 53.9 to 69.3 t ha -1 in plant cane and 44.1 to 56.7 t ha -1 in first ratoon. Giant reed fresh yields were significantly lower at 9.6 to 10.7 t ha -1 at Tecan, however hemicellulose (34.0%) and lignin (9.8%) concentration of giant reed was greater than the energycane ( % and %, respectively). Percent cellulose was similar across species at approximately 37%. Overall plant cane yields were lower and first ratoon yields were higher at Townsite than Tecan, but the same yield and fiber concentration differences between energycane genotypes and giant reed were observed. Our results indicate that energycane is a more appropriate bioenergy feedstock choice than giant reed for sandy soils of south Florida. 160

6 Thermophilic anaerobic digestion of cane sugar filter cake P. Horecký 1 and M. Saska 2 1 Business Development Director VWS MEMSEP s.r.o. a member of Veolia Water Solutions & Technologies Czech Republic 2, Louisiana sugar industry produces large volume of residual materials that are disposed at a cost to the mills. This material includes waste water, bagasse, boiler ash and filter cake. Most of these wastes contain biodegradable matter. This could be potentially resource for a biotechnology process which could produce extra by-products for the sugar industry. One possibility is using anaerobic technology for biogas production. The most suitable material appears to be filter cake. The preliminary experiments showed that producing biogas from filter cake is possible and it could be profitable to the cane sugar industry. WHY ETHANOL? Butanol Production and the Raw Mill. D.F. Day Butanol is an aliphatic saturated alcohol which can be used as a diesel fuel. The acetonebutanol fermentation was the standard method for industrial production of this solvent until the 1950s. Butanol has many advantages as an alternative fuel source; a higher energy content, usable in existing pipelines and easy to blend with gasoline or diesel. Like ethanol, butanol can be produced from sugarcane juice, molasses, sugar or bagasse hydrolysates. Ethanol production systems can be relatively easily retrofitted to produce butanol. Sugarcane juice and molasses ferment directly to butanol making this solvent a potential product for a raw mill based biorefinery. Research on How Mannitol Affects Sugar Crystallization in Raw Sugar Manufacture J. Wu Tiu Yen 1,2, C. Alexander 2, and G. Eggleston 2 161

7 1 ESCOM 1 Allee du Reseau Jean-Marie Buckmaster Compiegne, France 2 USDA-ARS-Southern Regional Research Center 1100 Robert E. Lee Boulevard New Orleans, LA 70124, U.S.A. The major (but not sole) contributor to deterioration in the U.S., particularly where warm and humid conditions prevail, is infection by hetero-fermentative Leuconostoc mesenteroides lactic acid bacteria. In recent years it has emerged that mannitol, a sugar alcohol, is a major product of Leuconostoc mesenteroides deterioration of sugarcane and a sensitive marker that can predict processing problems. Greater than ~500 ppm/brix of mannitol in sugarcane juice predicts downstream processing problems, but this threshold value may vary from region to region. Mannitol is much less soluble than sucrose at all temperatures. Mannitol forms needle-like crystals and star-like conglomerations of mannitol crystals are frequently observed at high concentrations of mannitol. At 10% mannitol levels in sucrose solutions (71 Brix), mannitol crystals tend to take over. The presence of calcium increases the solubility of mannnitol in such solutions as well as the solution viscosity. Investigations continue on the effect of mannitol on sucrose crystallization under industrial conditions using a 1 L laboratory crystallization unit as well as a 8 L pilot plant vacuum crystallizer (8 gal) manufactured by Honiron Corp. 162