My First Attempt at a LowCost Homemade （我第一次尝试低成本的自制）.pdf

My First Attempt at a Low-Cost Homemade Wind Turbine Dawn Jacobs April 19, 2012 Abstract I built a wind turbine using mostly salvaged materials in the hopes of using the homemade, off-grid power to charge my family’s many hand-held electronic devices. We have a total of 16 rechargeable devices in regular use in our household, requiring an estimated 112 watt-hours of energy each day. I planned to mount a small wind turbine (4-foot blade diameter) on our roof and store the power in a 12V Duracell Powerpack. We would then use the built-in standard receptacles on the Powerpack to charge our electronics. My wind turbine works successfully to produce power; however, the available wind at my location is not sufficient to produce the amount of energy required to meet the above needs. This is due to:  A high cut-in speed (12.5 mph) caused by the weight of the blades/hub and the internal friction of the generator.  The inefficiency of the homemade blades. The power coefficient, Cp, of my turbine was found to range from 0.12 to 0.16, as compared with typical Cp values of 0.4 for commercial wind turbines. Once the cut-in speed is achieved, my turbine performs as predicted for a typical home-made unit. During testing it produced on the order of 200W when wind speeds of 25 to 30 mph were obtained, and data confirmed the exponential relationship of power to wind speed. My wind turbine would perform well in a location where average wind speeds are typically high such as ridge-top and coastal regions. Problem With four people in our household, including two teenage boys, we have a large number of handheld electronic devices that require frequent charging. The amount of energy that we use for this purpose on a daily basis is estimated in Table 1. I wish to find a way to take these devices off- grid using a green renewable energy source. Table