Week 2 iLab –
* Compare/contrast commercial wind turbines "offshore" versus "on land".
Land wind turbines “on-shore” are installed in land-based applications, while “off-shore” wind turbines are installed over water. There are some advantages and drawbacks; such as the environmental impact of offshore wind is considerably reduced compared with those onshore; although noise and visual impact are questionable to be problems there are some concerns. For example, there could be an environmental impact such as localized disturbance of the seabed from the noise caused by the turbine underwater. Another fact are that off-shore turbines tend to have larger ratings, because the cost of installation is greater, according to estimates based partly on European experience since 1991, offshore wind energy costs are around 30-50% higher than onshore, due to larger machine size and the costs of transporting and installing at sea.
However, these prices are expected to drop as happened onshore as technology improves and more experience is gained. According to studies in Denmark wind resources with the key factor being water depth are currently considered economically reasonable up to 40 kilometers from shore. Also winds tend to be steadier in off-shore applications, so larger turbines will generate more power, and helps predict payback period and shorten it. A drawback about offshore is although many people, while agreeing that wind turbines are a useful strategy, are not happy to see them in their area because they do not like the looks of the ocean shoreline being filled with turbines. The technology is well developed but off-shore wind is expensive because of construction costs and bringing the power to grid. And also might be difficult to maintain the windmills out at sea.
* Compare the electricity created from a home wind turbine versus a home wind "spire". Wind spire, spins around a vertical axis, it can catch the wind from any direction to turn the rotor without re-orienting itself. The airfoils also spin more slowly than the tips of propeller style blades, rendering it virtually silent. Wind spire was specially designed with aesthetics and minimal cost in mind, around $ 5,000. Wind spire will produce approximately 2000 kilowatt hours per year in 12 mile per hour average winds, size: 30 ft. tall, 2 ft. wide. Wind turbine, collects kinetic energy from the wind and converts it to electricity that is compatible with a home’s electrical system. Homes are served by both the wind turbine and the local utility. Wind speeds must be 10 mph or higher. As the wind increases, turbine output increases and the amount of power purchased from the utility is proportionately decreased. When the turbine produces more power than the house needs, the extra electricity is sold to the local utility. This is done automatically. Usually homes use about 9,400 kilowatt-hours of electricity per year; a wind turbine rated in the 5 to 15 kilowatt range would be required to meet the demand.
* How many wind spires would your home (or use an average 2000 square foot home)? Need to cover your daily electrical needs? (Cite your references.) The number of wind spire that would be used in a house of 2000sf. is not known per square foot average, as the cost of a system in fact depends on know how much energy (kilowatt-hours, kWh) the owners you use daily, how many full sun hours you receive per day; and if you have other sources of electricity. Another fact is that depending on wind speeds in a particular area, a homeowner may install two or three systems to generate 100 percent of the required power. As an example one homeowner in Nevada installed a single Wind spire to generate about 25 percent of his home’s power supply. Each Wind spire will generate approximately 2,000 kWh a year based on 11 mph average annual wind speed. According to monthly average graphic below provided by AltE Store these examples represent only...
American Wind Energy Association. Resources. Wind Energy Basics.http://www.awea.org/faq/wwt_basics.html
"The Physics Fact book". http://hypertext book.com/facts/2003/BoiLu.shtml. Retrieved on 17 February 2009.
Wind Resources of Ohio. http://ohiowind.org/pdfs/OH_spd100m.pdf
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