PROOF-OF-CONCEPT COMBINED SHROUDED WIND TURBINE AND COMPRESSED AIR ENERGY STORAGE SYSTEM

摘要

As the push for renewable energy sources continues, one significant drawback over fossil fuels is that they are not reliable. Wind is not guaranteed at all times, and the sun does not always shine. Moreover, the demand for electricity is variable due to daily and seasonal swings in power draw from the grid. Conventional power plants can increase or reduce production to meet seasonal demand, but usually cannot meet daily fluctuations. Therefore, power plants must maintain a relatively high level of electrical generation capacity throughout the day even if the current demand is low. A prime place to focus upon electrical demand fluctuations and the unreliability of the renewable sources is at the location of the changes in demand. Homes often sit vacant throughout the day and draw little power from the grid. When residents return in the late afternoon and evening, a sudden increase in demand occurs. To address this increase in demand at a local level, a small-scale proof-of-concept shrouded wind turbine (SWT) and compressed air energy storage (CAES) system was designed, built, and tested for an undergraduate capstone design project. The concept is that a small SWT charges the CAES system and when the residents return, the energy stored within the CAES system is released lessening the demand on the main electrical grid. The SWT was investigated due to the theorized increase in efficiency that the shroud provides by accelerating the air beyond ambient velocity at the location of the turbine blades. The CAES system consisted of a three-stage compressor that filled a high-pressure scuba tank. This air was then released in a controlled manner in order to operate an air motor coupled to an alternator that generated electricity. Testing of the SWT found that the prototype was too small to power the compressors for the CAES; however, the concept of the SWT was shown to hold true. Experiments using the CAES system demonstrated significant losses, but it did generate electricity. The small-scale prototype did reveal that the idea of focusing on the source of the power fluctuations is a viable option. As a result, by using many small power production and storage devices, the overall daily swings in demand for electricity can be corrected to levels that current power plants can meet.