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Tulane First to Receive Real Time Simulator
Michael Strecker
Phone: (504) 865-5210
mstreck@tulane.edu
On Aug. 14, 2003, the largest power blackout in North America's history plunged 50 million people in eight states and Canada into darkness. Such a scenario could be prevented in the future thanks to HYPERSIM, a real-time simulator Tulane University's School of Engineering has acquired as the result of its long-running partnership with Entergy, the utility company that serves Texas, Louisiana, Mississippi and Arkansas.
Tulane is the only university in the country to house such a supercomputer, which was built by California-based Silicon Graphics, Inc. and Canada's Hydro-Quebec. Engineers will use the powerful simulator, in conjunction with an identical one at Entergy headquarters, to test the current power grid's performance in a variety of "what if" scenarios ranging from storms to sabotage.
"Normally, utility companies have to do such testing off-line on models of grids that won't be operational for five years. This will allow us to test a system as it is now," said Parviz Rastgoufard, Entergy Chair in Electric Power Engineering at Tulane.
Rastgoufard said the Real Time Simulator will bring vast benefits to the university as well as Entergy's customers. Rastgoufard and other Tulane faculty will use the simulator to teach electrical engineering students concepts of planning and operating electric power systems. Graduate students will assist in the coding and algorithm work necessary to create analytical software as well as responses to various disaster scenarios.
Entergy will benefit from the expertise Tulane engineers will offer them on preventing and responding to power grid threats.
Besides its use in the energy industry, HYPERSIM could also be used in simulating and analyzing worse-case scenarios in the shipbuilding, airline, space flight and other industries.
The simulator project, directed by Rastgoufard, is funded by the Entergy-Tulane Energy Institute. The Louisiana-based Clean Power and Energy Consortium (CPERC) will provide additional funding for the project over the next five years. Federal and state agencies and other national companies are also being solicited for project funding.
University-Industry-Government Collaborative Research in Gas Turbines
LSU Cogeneration Plant, GE Power Systems, Department of Energy and the Turbine Innovation & Energy Research (TIER) Center are involved in a unique partnership with the goal of developing the next generation gas turbines with improved efficiency and reduced losses. According to TIER Center Director Professor Sumanta Acharya, “Such a broad-based partnership blends fundamental research with the development of improved energy generation technology leading to reduced fuel utilization and energy costs”. This research is being conducted, in part, under the auspices of the Clean Power and Energy Research Consortium (CPERC) which integrates the energy programs at Louisiana State University (LSU), University of New Orleans (UNO), Nicholls State University, Southern University and Tulane University. The TIER Center represents LSU in the CPERC consortium and is spearheading research in several areas including: improving performance and reliability of gas turbines leading to reduced fuel utilization, use of synthetic gas (H2+CO) from coal or bio-mass and Liquefied Natural Gas (LNG) for energy generation, reducing emissions from power plants, and in the development of fuel cell technology for energy and power.
In cogeneration or combined heat and power (CHP) power is produced using a gas turbine generator, and the excess heat from the exhaust of the gas turbine is used to generate steam that can then be used to drive a steam turbine and/or for heating, ventilation and air-conditioning (HVAC) application. Since the excess heat is not wasted, cogeneration plants have relatively high efficiencies. In order to address campus power and HVAC needs, LSU decided in 2002 to install a cogeneration plant.
 The plant which has recently been completed delivers nearly 18 MW of power to the campus, and consists of a General Electric LM2500 gas turbine unit (see picture on right), a heat recovery steam generator (HRSG) to generate steam from the excess heat in the turbine exhaust, and a York steam chiller that produces chilled water for campus-HVAC. Unused steam is also utilized for campus space heating and providing hot-water supply.
To develop and improve existing gas turbine generators, flow, pressure and temperature data is needed in the actual engine. In order to obtain additional thermal data on the first stage vanes which are exposed to the highest temperatures, General Electric (GE) is providing TIER with a fully-instrumented hot cascade facility for making these measurements. This facility fabricated at a cost of over $0.5 million will be used for collecting film cooling data over the end walls and the turbine blades. This is a unique facility that includes both the combustor and the first stage vanes, and can therefore reproduce a more realistic engine environment compared to most other university laboratory facilities. Typical pressures and temperatures in the first stage vane are 5-6 atmospheres and 1000 0F.
 As part of the DOE project three-dimensional end-wall contouring concepts (see figure on right) are being examined to see if the thermal loading to the end wall and aerodynamic losses in the vane can be reduced. Preliminary results in a cold cascade indicate that end-wall contouring can lead to reductions in coolant usage and improvements in aerodynamic efficiency. Greater efficiencies translate to reduced fuel consumption and energy savings. These results are now being verified in the GE-hot cascade facility. Based on this work improved end wall designs will be developed and provided to the gas turbine industry for possible adoption in modern gas turbines.
Another aspect of the collaborative project is exploring leading edge contouring by simply adding a fillet to the blade leading edge. An example of such contouring is shown in the figure below on the left. Such contouring leads to significant reductions in the pressure loss as shown below in the pressure-loss coefficient (Cpt,loss) contours for the baseline blade and filleted blade profiles. These reductions in the pressure loss translate to improvements in efficiency and reductions in fuel usage per KW of power generated.
The design improvements developed as part of the collaborative will be transferred to the industry, and this technology transfer can contribute to the development of the next generation engines for power production. The net result of this research are: greater efficiency, reduced fuel consumptions and reductions in energy costs. This is particularly important to the state of Louisiana which is one of the largest consumers of energy in the country and reductions in energy costs can benefit the state in a measurable way.
The above project is an example of how CPERC is partnering with industry and government to help drive down energy costs.
For additional technical information contact: Professor Sumanta Acharya, TIER Center Director, acharya@me.LSU.edu, 225-578-5809
For information on CPERC contact: Mr. Charles Cusimano, LSU Board of Supervisors, LSU System Building, Baton Rouge, Louisiana 70803
Fuel Alcohol Production from Post-Harvest Sugarcane Residue: CPERC Sponsored Research at Nicholls State University
Sugarcane has been an integral part of the south Louisiana economy and culture for more than 200 years. Sugarcane arrived in Louisiana with the Jesuit priests in 1751 and, in 1795, Etienne de Bore granulated sugar on a commercial scale at Audubon Park in New Orleans. The Louisiana sugar industry is in its third century of existence, having celebrated its 200th year of continuous sugar production in 1995 . Louisiana is the second largest U.S. sugarcane producer, with sugarcane production accounting for 41.4% of the nation’s total.
Post-Harvest Sugarcane Residue
In 2001, sugarcane was grown on 493,773 acres by 773 producers in 24 Louisiana parishes. An estimated 465,000 acres were harvested for sugar, with a total production of 1,554,965 tons of sugar. The total acreage reported in 2001 was about the same as reported in 2000, which had set a new record for the Louisiana sugar industry. The sugarcane plant consists of about 75 to 80% net cane (stalks) from which the juice is extracted and the sugar crystallized. The other 20 to 25% of the plant consists of leafy material, including tops, from which little or no sugar is produced. This leafy material is called trash or post-harvest residue. This residue accounts for 3 to 10 tons per acre. Every year during and after the harvest the residue, mainly leaf litter, is burned by open air burning by the sugarcane farmers. This is done for two reasons: (1) to remove fibrous content which would greatly reduce milling efficiency and decrease profits and (2) at 3 to 10 tons/acre this residue in the field is unmanageable to the farmer for farming practices for subsequent cultivation. The current practice of open air burning of post harvest sugarcane residue not only affects air quality, but increasingly the general public is objectionable to this practice. The sugarcane farmers are looking for alternative to burning of the residue and if the sugarcane residue could be used to produce fuel alcohol via fermentation process, it will be a win – win situation.
The sugarcane residue is available every year. At an average of 5 acres/ton and with 465,000 acres in sugarcane cultivation, the amount of residue available is over 2.3 million tons/year. This is a renewable resource and could be used to produce energy in the form of ethanol.
Bagasse
Sugarcane refining generates a large volume of residue called bagasse. Disposal of bagasse is critical for both agricultural profitability and environmental protection. The sugarcane stalk consists of two parts: an inner pith containing most of the sucrose and an outer rind with lignocellulosic fibers. During refining, the sugarcane stalk is crushed to extract sucrose. This procedure produces a large volume of residue, bagasse, containing both crushed rind and pith fibers. In Louisiana, there are 16 sugar mills located in three regions, namely, Northern region, Teche Region, and River-Bayou Lafourche Region. On a yearly basis, approximately 5 million tons of bagasse is produced in the sugar mills of Louisiana. According to LSU Ag center approximately 75% of bagasse is used as in-house fuel for power generation or as raw material for producing low-value products such as mulch and ceiling tiles. The remaining 25% is waste that goes to a landfill or is allowed to decay and this 25% accounts 1.25 million tons of bagasse, which could be used for ethanol production every year.
Leaf stripping in Sugar Mill
The excess leafs that are brought to the mill along with cane stalk are usually converted to bagasse during the sugar production process. Some mills are separating leafs out of the process by using blowers and collecting these leafs as leaf stripping in the mill. The leaf stripping accounts for 5%/ton of processed canes. Currently, the Enterprise sugar mill in Iberia parish has half of its cane processed through leaf stripping process (diffusion process). This mill processed over 1 million tons of cane through diffusion process this year and this generated 50,000 tons of leaf in the mill. This is another source of raw material for ethanol production.
Ethanol Production
The close physical and chemical association between lignin and plant cell-wall polysaccharides is a major limitation to efficient utilization of sugarcane residue for ethanol production. A variety of pretreatments have been applied to agricultural residues and wood in an effort to increase the susceptibility of cellulose in these materials to enzymatic hydrolysis. Most of these pretreatments do increase the yield of glucose obtainable from lignocellulosic materials, but the yields are well below the theoretical maximum. In nature, lignin is degraded by various organisms, primarily to increase the amount of cellulose available for enzymatic digestion. Although the mechanism of natural lignin degradation is largely unknown, it is thought that oxidants such as hydrogen peroxide may play an important role. Hydrogen peroxide is known to react with lignin under certain conditions and has been widely used for many years to bleach high-lignin wood pulps. Delignification of wheat straw and corncobs by hydrogen peroxide has been reported. In this research, we demonstrate that the hydrogen peroxide treated sugarcane residue can be rapidly fermented to ethanol with greater than 92% overall efficiency. The major objective of this research is to evaluate whether alcohol can be made from fermentation of post-harvest sugarcane residue and to optimize a pre-treatment condition for high-efficiency alcohol production.
Results
Research at Nicholls State University explores the possibilities of making alcohol from the sugarcane residue. A chemical pre-treatment process using alkaline peroxide was applied to remove lignin, which acts as physical barrier to cellulolytic enzymes. Two yeast strains including Saccharomyces cerevisiae ATCC strains 765 and 918 were used in the experiment. The pre-treatment process effectively removed lignin. Alcohol production in the culture sample was monitored using gas chromatography. The results indicate that ethanol can be made from the sugarcane residue. The fermentation system needs to be optimized for evaluating the economics of producing ethanol from the sugarcane residue.
Figure 1. Solubilization of lignin from post-harvest sugarcane leaf treated with various concentrations of hydrogen peroxide at a pH of 11.5. Data represent means of four replications and the error bars indicate the standard deviation.
Figure 2. Solubilization of lignin from post-harvest sugarcane leaf treated with 1% hydrogen peroxide at various pHs. Data represent means of four replications and the error bars indicate the standard deviation.
Figure 3. Ethanol production by Saccahromyces cerevisiae strain 765 from the post-harvest sugarcane leaf pretreated with 1% hydrogen peroxide at pH 11.5. Data represent means of four replications and the error bars indicate the standard deviation.
Figure 4. Ethanol production by Saccahromyces cerevisiae strain 918 from the post-harvest sugarcane leaf pretreated with 1% hydrogen peroxide at pH 11.5. Data represent means of four replications and the error bars indicate the standard deviation.
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