Student Abstracts: Engineering at NREL

Realizing a Biorefinery by Expanding the Sugar Platform: Monosaccharide Separation. PAUL ALBERTUS (University of Michigan, Ann Arbor, MI 48109) KEITH NEEVES (National Renewable Energy Laboratory, Golden, CO 89401) .
The development of a biorefinery'a plant fed only by biomass and capable of producing multiple products, from fuels to plastics to pharmaceuticals'represents an important step toward the transformation to a sustainable society. The monosaccharides of biomass; glucose, xylose, mannose, galactose, and arabinose-may serve as the basis for a renewable chemicals industry. In order to take advantage of each monosaccharide's unique structure they must be separated from each other and the other components of biomass. Simulated moving bed (SMB) chromatography is one method for industrial scale sugar separations. Its complexity requires that a computer model be used to predict flow rates and switching times. Therefore, batch chromatography was used to determine the values of the parameters needed to construct a computer model of a SMB system. Pure component isotherms for each of the five monosaccharides at various concentrations, and competitive isotherms, in which multiple monosaccharides were included in a single pulse, were gathered. Flow rate and column length was varied to determine their effect on elution profiles. From these isotherms, it was clear that for monosaccharide concentrations similar to that from a slipsteam of hydrolysate from a bioethanol process, elution time is independent of monosaccharide concentration and the presence of multiple monosaccharides. Increasing residence time only modestly improved the separation. The computer model generates theoretical elution profiles that can be matched to the experimental ones by varying flow parameters. The correct parameters will be used by the model to aid in a full-scale experimental verification of the separation.

Cost and Performance Analysis of Evaporative Cooling Enhancement for Condensers at Empire Energy Geothermal Plant. DAVID COSTENARO (Washington University, St. Louis, MO 63105) CHUCK KUTSCHER (National Renewable Energy Laboratory, Golden, CO 89401) .
Many of today's geothermal power plants are located in arid climates. With water at a premium, air-cooled condensers are often used instead of wet-cooling towers. During the hottest times of the day, plant performance suffers as the "cold sink" (the ambient air) rises in temperature. For summer peaking utilities, these are also the times when grid power demand is highest. To boost the performance of a particular plant in Empire Nevada during these problematic peak hours, we have explored four methods for enhancing air cooling using evaporative means: 1) spray cooling, 2) Munters packing media-cooling, 3) deluge cooling, and 4) a hybrid combination of spray and Munters. A detailed Microsoft Excel spreadsheet is used to evaluate the performance and cost characteristics of each system operating in the Empire environment. It is concluded that the deluge cooling system, despite potential scaling on the condenser tubes, is the most economical way to optimize the plant's performance. The danger of scaling is dealt with by adding a purified water rinse to wash away new-forming scale whenever the deluge system shuts down.

Renewable hydrogen.. MALENE SAVAGE (Clark Atlanta University, Atlanta, GA 30314) BOB EVANS (National Renewable Energy Laboratory, Golden, CO 89401) .
Many efforts have been made to produce a competitive alternative to natural gas. Natural gas lowers the pollution but it is expensive and limited. One leading idea is that of renewable hydrogen. Renewable hydrogen has the potential of being cost effective and environmental friendly. The strategy is based on producing hydrogen from biomass pyrolysis using a co-product strategy to reduce the cost of hydrogen. During the first steps slow pyrolysis is used to maximize the yield of charcoal using densified peanut shells. Results were produced using the molecular beam mass spectrometer and the differential scanning calorimeter. MBMS produced kinetic data analysis that will help in predicting time and temperature requirements. The DSC produced information needed for heat requirements. All of the data gained from this summer will be used in the planning of the project.

Re-Design of a Hydraulic Oil Delivery System for Wind Turbine Blade Fatigue Testing . JAMES STACK (Bucknell University, Lewisburg, PA 17837) WALTER MUSIAL (National Renewable Energy Laboratory, Golden, CO 89401) .
The advancement of the wind energy industry is very much dependant on the ability to test the equipment being used in order to learn about their properties and make improvements in future designs. One type of test commonly performed is a fatigue test, which involves using hydraulic actuators to simulate the cumulative loading a blade will experience during its lifetime. Currently, new larger wind turbines are being produced with rotor blades spanning over 80 m which are stretching the testing capabilities of many test facilities. The Industrial User Facility at the National Wind Technology Center in Colorado is the premier wind turbine structural testing facility in the country and has just received a set of these new large-scale blades to test. But in order to maintain the speed at which these tests can be performed, the oil-pumping capacity of the hydraulic delivery system must be upgraded substantially, from the current rate of about 150 GPM up to 280 GPM. This paper focuses on the re-design of the hydraulics delivery system at the IUF, which involves combining two large pumps to operate in parallel, as well as the installation of a new oil cooler and larger piping to deliver the increased oil flow to the actuators in the test section.

Evaluation of the Smithsonian Environmental Research Center Two-Story Visiting Scientist Housing Designs Using Energy-10. RAINA STRICKLAN (Colorado State University, Fort Collins, CO 80523) ANDY WALKER (National Renewable Energy Laboratory, Golden, CO 89401) .
The Smithsonian Environmental Research Center (SERC) is located in Edgewater, Maryland. Plans to build visiting scientist housing have been submitted to the Federal Energy Management Program for energy analysis using Energy-10. Energy-10 is a software program that conducts annual hourly evaluations of a building's energy use. It uses thirteen energy efficient strategies to apply to a building to analyze energy efficiency. Modifications had to be made to the program since Energy-10 was designed to be used before the building design process, and the SERC blueprints were already drawn up. Insulation, air leakage control, high efficiency HVAC, and duct leakage strategies were considered for the SERC housing. Additional modifications were made to simulate a ground source heat pump, a waste water heat recovery system, and a solar water heater. Each strategy was analyzed separately, showing insulation and a waste water heat recovery system paired with a solar water heater to offer the greatest energy savings. Strategies were also combined to account for synergistic effects. By implementing a PV system, additional energy would be saved, generating 64% annual energy use savings over the SERC housing as planned. Implementation costs were not estimated as part of this study.

Development of a Weather Correction Model for Outdoor Vehicle Testing. DANIEL TUHUS-DUBROW (Brown University, Providence, RI 02912) ROM MCGUFFIN (National Renewable Energy Laboratory, Golden, CO 89401) .
When a vehicle sits all day in the sun, its cabin air temperature can reach as high as 80°C, and the dash temperature can reach 120°C. This requires a great deal of air-conditioning power for the initial cool-down of the vehicle. The National Renewable Energy Laboratory is currently looking into methods for reducing peak solar loads in vehicles, examining such technologies as solar reflective glazings, improved thermal insulation, and ambient venting systems. Two Lincoln Navigators are being tested outside the Thermal Test Facility for this purpose. One problem with outdoor testing of any kind is that the weather is always changing, and this could have an important effect on the results of the test. For example, if one technology was tested on a cloudy day, and another one on a sunny day, comparing the results would be meaningless. In order to account for these variations, a weather correction model has been developed. This is a two-node model that predicts the temperature rise in the cabin air and the cabin mass. "Standard" weather conditions are then chosen, and the measured data are normalized to these standard conditions so that different tests can be meaningfully compared. Results from the model are promising, but more testing must be done before the weather corrector can be put into use.