R. Nolan Clark

Wind Speed Power Spectrum Analysis for Bushland, Texas, USA

Numerous papers and publications on wind turbulence have referenced the wind speed spectrum presented by Isaac Van der Hoven in his article entitled Power Spectrum of Horizontal Wind Speed Spectrum in the Frequency Range from 0.0007 to 900 Cycles per Hour (Journal of Meteorology, Vol. 14, 1957, p. 160). Van der Hoven used data measured at different heights between 91 and 125 meters, and represented the high frequency end of the spectrum with data from the peak wind speed hour of hurricane Connie (13 August 1955). Because the data were collected in such special conditions we should question the use of his power spectrum in the wind industry. We computed a power spectrum for Bushland, Texas, from 13 years of hourly average data, 1 year of 5 minute average data, and 2 particularly gusty days 1 second average data all collected at a height of 10 metres. While the general shape is similar to the Van der Hoven spectrum, few of his peaks were found in the Bushland spectrum.

Remote solar, wind, and hybrid solar/wind energy systems for purifying water

Solar energy, wind energy, and a combination of wind and solar energy have been used successfully to power an UV (ultraviolet) water purification system. Five different solar and wind energy systems have been tested and although these renewable energy systems have been used for water purification, graphs contained in the paper can be used to determine the feasibility of powering other electrical loads. Combining a 100-W solar-PV system with a 500-W wind turbine resulted in pumping and purifying enough water to satisfy the potable water requirements of 4000 people (16000 liters/day) at an estimated equipment cost of

Livestock Water Pumping with Wind and Solar Power

4630.

The Influence of Feedlot Pen Surface Layers on Microbial Community Structure and Diversity

Recent developments in pumping technologies have allowed for efficient use of renewable energies like wind and solar to power new pumps for remote water pumping. A helical type, positive displacement pump was developed a few years ago and recently modified to accept input from a variable power source. This pump was tested at different pumping depths with both solar and wind energy power sources. The solar power source consisted of 640 W of photovoltaic panels and the wind power source was a 1000 W wind turbine. For Bushland, Texas, the solar powered pump provided enough water for the 150 beef cattle in the summer months of June, July, and August and was adequate in winter months when water consumption was lower. The wind powered pumping system provided sufficient water in summer for the same number of cattle (150 head), but had excess water in the winter and spring when winds were higher and water consumption was lower.

Potential use of wind power for pumping irrigation water

The biological and chemical characteristics of feedyard pen surfaces have the potential to affect environmental conditions with respect to air and water quality. Little is known about feedyard pen surface chemistry and that of the underlying microbial community structure. The feedlot surface profile has been described as four layers: the unconsolidated (or loose surface), dry-pack, wet-pack, and soil layer. It was determined that NO3-N concentration was greater in the soil layer than in the manure layers whereas NH4-N concentration was greatest in the wet-pack layer. In this study, we characterized the microbial communities associated with these four feedlot layers using the DGGE-PCR method employing a suite of primers that target 16S and 18S rDNA. The distribution of microorganisms intimately involved in the cycling of N such as the ammonia-oxidizing bacteria (AOB) found within the Betaproteobacteria and the nitrite-oxidizing bacteria (NOB) found in the Alphaproteobacteria division was determined. The influence of the feedlot layers on microbial community structure was observed in the spatial grouping of DNA fingerprint patterns and as assessed by two indices of diversity. Different lineages of AOB were found to be associated with these feedlot layers which imply a microbial ecosystem that is uniquely influenced by the physical and chemical properties of these feedlot layers. Both AOB and NOB communities are present in all feedyard pen surface layers for nitrification of ammonia to occur. The wet-pack layer showed a marked reduction in both fungal diversity and evenness. A feedlot pen surface may be viewed as a distinct microbiological island.

Irrigation Pumping with Wind Energy—Electrical vs. Mechanical

Abstract The potential energy savings from three types of wind powered irrigation pumping plants were determined for selected areas of the U.S.A. The wind systems analyzed were: wind assist combustion engines; wind assist electric motors, with and without the sale of surplus electricity; and a stand-alone turbine with a reservoir for water storage. Because of the reduced wind power available and the relatively short time span during the irrigation season, the wind assist turbines will only provide between 6 and 31% of the required energy for pumping water. In all regions, the amount of electrical energy available for sale from the wind assist system is greater than the energy saved. The stand alone turbines can provide all the energy required for pumping the irrigation water; however, their use will require the installation of a reservoir for water storage. Thus, the stand-alone systems are suitable only in locations where surface irrigation systems can be used or where other energy sources can be used to pressurize the water distribution system. The size distribution of the on-farm irrigation pumping plants in the U.S. for zones of similar average wind power during the principal irrigation season is presented. The mid and southern Great Plains areas which have the largest potential wind power during the primary irrigation season account for over 32% of the nations pumping units.

Using Rotor or Tip Speed in the Acoustical Analysis of Small Wind Turbines

ABSTRACT DURING the past few years, researchers have been examining new wind energy systems to pump the large volume of water needed for irrigation. One new system uses a vertical-axis wind turbine to generate electricity that is compatible with utility grid power, and the pump is powered by this electrical system using a conventional electric motor. Another new system uses a vertical-axis wind turbine to produce mechanical power, and the pump is powered directly with this mechanical power or in combination with a diesel engine or electric motor. When the efficiency of converting wind energy to pumped water is compared for the two systems, the mechanical system provides 12% more energy than the electrical system. However, the electrical system is 2.5 times more profitable than the mechanical system because irrigation pumps are used seasonally. With the electrical system, energy generated in the non-irrigating season can be sold to the utility, but the mechanical system is only utilized when water is needed.

Size Distribution of the On-Farm Irrigation Pumping Plants in the U.S.

Acoustical noise data have been collected and analyzed on small wind turbines used for water pumping at the USDA-ARS Conservation and Production Research Laboratory (CPRL) near Bushland, TX. This acoustical analysis differed from previous research in that the data were analyzed with rotor or tip speed being the independent variable in addition to analyzing the data with wind speed as the independent variable. Acoustical noise generation was analyzed for two different wind turbines which were tested with different blades. The averaging period for acoustical noise data was one second instead of one minute (smallest time increment recommended in IEC wind turbine noise standard) since the sound pressure level of small stand-alone wind turbines can vary significantly over just a few seconds. Disconnecting the wind turbine from the water pump motor by the pump controller was shown to significantly increase the noise of the wind turbine.

Electrical Generation Using a Vertical-Axis Wind Turbine

ABSTRACT OVER 473,000 on-farm pumping plants were used to pump and deliver irrigation water in the United States in 1979. Over 60 percent of these units were smaller than 37.3 kW (50 hp) and only 9 percent of the units were larger than 74.6 kW (100 hp). Nearly one-half of the pumping plants (231,440) were located in the six High Plains States of Colorado, Kansas, Nebraska, New Mexico, Oklahoma and Texas.

Ammonia emissions from a beef cattle feedyard on the southern High Plains

ABSTRACT TRADITIONALLY, windmills have been of the propeller or multiblade types, both of which have their rotational axis parallel to the flow of the wind. A vertical-axis wind turbine has its rotational axis perpendicular to the flow of wind and requires no orientation to keep the rotor in the windstream. The vertical-axis wind turbine operates on the same principle as any airfoil by producing lift and drag forces. A newly designed 100-kW vertical-axis wind turbine has been operated for one year at the USDA Conservation and Production Research Laboratory, Bushland, Texas. The turbine has an induction generator and supplies power to a sprinkler irrigation system with excess power being sold to the electric utility. The turbine begins producing electric power at 5.5 m/s windspeed and reaches its rated output of 100 kW at 14 m/s. The unit has obtained a peak efficiency of 43% at a windspeed of 7 m/s or 73% of theoretical maximum. Using 17 years of windspeed data from the National Weather Service, the annual energy output is estimated at 200,000 kWh. The unit has experienced several operational problems during its initial testing. Guy cables were enlarged to provide greater stiffness at the top of the turbine to reduce blade stress levels. Also, the main contactor shorted and the brake system required a complete redesign and modification. The turbine was capable of operation about 60% of the time.