Journal of Energy Engineering

The events leading to the sudden and catastrophic failure of the North American power grid during August 2003 coupled with a record hurricane season a year later have civil engineers rethinking cost-effective backup power solutions for their clients. Electric deregulation across many areas of the United States has utilities looking for new value-added products and services to protect and acquire market shares. As a result, a new partnership has emerged between site planners and utilities to provide affordable backup power to the customer. Case studies are provided for a $1.0\mathrm{MW}$ backup power project for a 367-bed hospital and a $1.25\mathrm{MW}$ parallel power project for an insurance call center located in Gainesville, Fla. Results for each show competitive pricing for the client and attractive returns for the utility.

Generation of electrical energy from wind can be economically achieved only where a significant wind resource exists. Because of the cubic relationship between wind velocity and output energy, sites with small percentage differences in average wind speeds can have substantial differences in available energy. Therefore, accurate and thorough monitoring of wind resource at potential sites is a critical factor in the siting of wind turbines. An accurately measured wind-speed frequency spectrum at a site is another important factor. For assessment of the wind-power potential of a site, most investigators have used simple wind-speed distributions that are parametrized solely by the arithmetic mean of the wind speed. Assessment of power output of a wind turbine will be accurate if the wind speeds measured at the hub height (30–50 m) of a wind turbine-generator are known. However, the existing wind data available at most of the meteorological stations worldwide is measured at a height of 10 or 20 m above the ground. Therefore, wind speeds measured at anemometer heights are extrapolated to the hub height of the wind turbine. Many investigators have proposed simple expressions for height extrapolation of wind speeds. This paper reviews wind-speed prediction and forecasting, and development of techniques for accurate assessment of wind-power potential. Also, the need of wind-resource assessment and the techniques and methods used for it are highlighted.

There are growing provisions to include ocean wave energy as an alternate renewable energy source. There are also several challenges that need to be addressed before the technology gains full engineering and market confidence. One of the main technical hurdles is the need to address part-load problems of wave energy converters resulting from bathymetric conditions and variations in wave parameters such as wave frequency and height. As such, the wave phenomenon is inherently variable in time and space. This is compounded by the fact that wave energy conversion devices are less efficient at part load. This paper discusses sources of part loads in wave energy conversion including their impact on system efficiency for a California weather scenario, also relating wave energy conversion techniques to part-load efficiencies.

Energy conservation inside the buildings is of utmost importance. To reduce the heating and cooling loads inside the energy-efficient buildings, solar entry regulation as per season can be attained with the use of specific sunshades. Although various static sunshades have been developed depending upon solar geometry, the efficiency with respect to control of solar entry inside the building is a major concern over the seasonal classification for a particular geographic location. The proposed work aims at the design development of a new static sunshade depending on solar angles, whose efficiency has been experimentally verified using a small-scale modeling technique. Three experimental models of insulating material were prepared with varying aspect ratio of windows and static sunshades. Sunlit area, which in turn controls the temperature inside the models, has been made the criteria for deciding the effectiveness of the proposed sunshade over existing horizontal sunshade. The proposed technique can be applied at any geographic location over the world for which sunshade can be designed as per the climatic requirements of the place.

An equation is proposed to relate the efficiency of a steam-turbine plant (STP) to the pressure drop $\Delta P$ across the plant. The equation considers a STP operating on the Rankine cycle as a system and takes into consideration both thermodynamic and fluid-dynamic aspects of its work. The correlation between this equation and the experimental data was estimated. The physical meaning of the coefficients was established and their numerical values in a wide range of temperature and pressure variations were determined. The equation makes possible functional monitoring of an operating turbine. It can be useful in upgrading and optimizing individual units or designing a new STP.