SEAS Seminar Archive
February 21, 2013
Inanc Senocak, High-Performance Simulation Laboratory, Department of Mechanical & Biomedical Engineering, Boise State University
There is a need for a short-term wind energy forecasting capability that can resolve wind speed and direction over complex terrain where significant number of wind farm installations has occurred in recent years. An accurate forecasting capability can be used to address load-balancing issues that arise from intermittent winds, and also to increase powerline capacity using the dynamic rating concept. However, there is substantial amount of uncertainty when predicting wind speed and direction over complex terrain, and any wind solver should also operate in the forecasting mode to be a useful tool in real applications.
To address these challenges, a multi-scale forecasting engine is proposed on emerging clusters of graphics processing units (GPU). In this engine, a regional weather forecast model will be executed on central processing units (CPU), whereas a micro-scale wind forecasting model will be executed on the GPUs of the same cluster in a multi-scale fashion. The microscale wind solver adopts a Cartesian mesh immersed boundary method to resolve arbitrarily complex terrain. A large-eddy simulation method with a Lagrangian dynamic subgrid scale method is used for turbulence closure. The Cartesian mesh topology maps well to the computer architecture of modern GPUs resulting in significant speedups in computations. Dual-level parallelism in the solver is achieved by interleaving MPI programming with CUDA. Equally important, a parallel amalgamated geometric multigrid method is implemented to accelerate the computations numerically. Parallel performance analysis and the Bolund Hill experiment are used to demonstrate the current state of the wind solver and identify areas for further research.
April 27, 2012
Mark A. Handschy, Enduring Energy, LLC
Julie Lundquist, University of Colorado
Variability of electric generation from renewable wind and solar resources poses a challenge for regulation and stability of the electric grid. It has been widely suggested that this variability can be reduced by aggregating geographically diverse generators, with a benefit determined by the degree of correlation between sites. Here, we propose a general quantitative form for site-to-site correlation using a simple model that shows how the geographic size of an aggregation region affects the time scale of electric-grid regulation requirements for wind and solar power.
Wind speed power spectra exhibit the same dependence on temporal frequency (f-5/3) as on spatial wave number (k-5/3), which suggests a characteristic velocity connects space and time domains even when atmospheric turbulence is not "frozen" as required by Taylor's hypothesis. With this connection, the temporal cut-off frequency below which trends are removed from time-series data substitutes for the outer spatial scale in determining correlation length. Some previously published results for wind-speed correlations seem to agree with this conjecture. Data for solar irradiance also show similar scaling, indicating that wind influence on cloud size, shape, and motion may determine solar power variability statistics.
June 17, 2011
Laura Hinkelman, Joint Institute for the Study of the Atmosphere and Ocean at the University of Washington
Widespread deployment of photovoltaic (PV) energy production systems requires understanding the spatial and temporal variability of the available solar irradiance. This talk presents the results of variability studies conducted using data from 17 radiometers deployed by the National Renewable Energy Laboratory (NREL) at a site on Oahu Island.
Istvan Laszlo, NOAA/NESDIS, Center for Satellite Applications and Research (STAR)
Solar radiation at the surface from GOES data in real time has been routinely estimated at the National Environmental Satellite, Data and Information Service (NESDIS) of the National Oceanic and Atmospheric Administration (NOAA). Currently available and planned products will be described along with the techniques used to produce them.
March 17, 2011
Offshore measurements of wind flow characteristics aloft for wind energy using ship-borne High-Resolution Doppler Lidar
Yelena Pichugina, NOAA/CU CIRES
The development of offshore wind energy is an application that requires accurate information on wind speeds above the surface at the levels occupied by turbine blades. Little measured data are available at these heights, and the behavior of near-surface winds is often unrepresentative of that at the required heights. As a consequence, numerical model data, another potential source of information, is unverified at these levels of the atmosphere. In this presentation a motion-compensated, high-resolution Doppler-lidar-based wind measurement system capable of providing needed information on winds in the offshore zone is described. The emphasis here is on high-resolution (<10m), high-precision profiles of wind speed and direction averaged over 15-min, calculated from the lidar scan data. Examples include time-height cross sections, time series, and distributions of quantities such as wind shear through the blade layer. Deviations between values of wind speed calculated from power-law profiles and those measured by the Doppler lidar will be presented.
December 2, 2010
Steffen Rebennack, Assistant Professor, Colorado School of Mines, NREL
Dr. Rebennack will discuss the reduction of CO2 emissions in the electricity sector, which poses several challenges when a CO2 emission cap is imposed. On the one hand, policy makers face the problem of choosing the "right" level of CO2 emission allowances with respect to environmental goals and economic tractability and, on the other hand, the electric utilities have to cope with uncertain CO2 prices in case of a Cap-and-Trade system. Dr. Rebennack proposes a stochastic programming formulation to calculate the operational cost when imposing different CO2 allowances emission quotas on the hydro power system.
Anneliese Alexander, Research Associate, NOAA ESRL
Ms. Alexander will discuss a study that is being conducted to determine the optimal renewable energy system over the conterminous United States using historic weather observations and land-use limitations. It is based on the projected renewable energy output that would be obtained given weather conditions over a three-year period on a 13km resolution grid. The minimization study looks for the lowest-cost renewable energy system assuming that natural gas would be used to make up any shortfalls in electricity production from renewable resources and assessing a penalty for wasted over-production of electricity. The complexity of how to approach such a minimization will be discussed. Some initial results showing the amount of fossil fuel backup required will be shown, as well as initial breakdowns of the location and number of wind turbines, solar photovoltaic, and concentrating solar plants that should be installed.
September 23, 2010
Lead Author Dave Corbus, NREL
Lead Author Debbie Lew, NREL
August 26, 2010: Energy-Water Nexus Seminar
Jordan Macknick, NREL
As the nation's electricity infrastructure changes in the coming decades, concentrating solar power (CSP) technologies are likely to play a large role. However, there has been much concern recently over the water requirements of CSP plants, which can have a higher operational water intensity than conventional energy technologies. As CSP is likely to be deployed in the arid Southwest, there is a potential for water rights conflicts to stall or prevent CSP installations. Water use in CSP plants can be significantly reduced by using different generation technologies and different cooling systems. Such technology changes may have tradeoffs in terms of plant performance and total costs, the magnitude of which are highly dependent upon the climatic conditions of the CSP plant location.
Lawrence Flowers, NREL
In the US, cooling thermal power plants uses more water than any other sector, including agriculture. There are more than 35,000 MW of wind energy installed in the US; more than 10,000 MW of that is in the West. DOE's wind future report indicates of the 300,000 MW needed for a 20% energy penetration of the US electricity grid, the West would have 76,000 MW installed. Each MWh produced by wind saves 200-700 gal of water, which would otherwise be consumed in cooling thermal power plants. A 20% wind future would save 4 trillion gals of water by 2030, and 435 billion gal/yr thereafter.