Wind Power A Clean, Renewable, Form of Energy
Wind power, or wind energy, is a renewable resource; it is from the sun. The intensity of solar radiation differs across the globe. Some areas receive intense amounts of sunlight, while others receive much less. The result is a temperature gradient; a gradient which is mediated by the flow of air to and from areas of dissimilar temperatures and pressure systems in our atmosphere. Uneven heating of the earth's atmosphere, in addition to irregularities on the earth's surface and the rotation of the earth create wind. Terrain, water bodies, and vegetation then shape flow patterns.
History of Wind Power
The recent history of wind power in the United States has a similar impetus to that of alternative fuel sources in general-- it was an idea borne from the 1970's Oil Crisis. It does, however, have a more extensive history reaching back into to late 19th century in the colonization of the American West; millions of windmills were erected for irrigation and cattle purposes to facilitate the growing number of farms and ranches. 1900 but soon feel into disrepair as inexpensive energy sources became more widespread and grid power extended its reach into rural areas used small electric wind systems.
Outside of the US, however, wind power has a broader history. In fact, there was evidence that boats were propelled along the Nile as early as 5000BC via wind energy. China used wind for pumping water several millennium ago.
Wind Power-harnessing wind energy for power purposes
Wind is harnessed to make mechanical power or electricity. The kinetic energy from the wind is converted through various different processes to create mechanical energy that can be used in lieu of fossil fuels. Although there exists some variety in the size and shape of the turbines, they perform the same function as illustrated in the following diagram:
· Wind turbines-similar to propeller blades-are erected in areas of high wind flow.
· Movement of the turbine powers an electric generator. The power is fed through a transmission before being released into the generator. The transmission keeps the generator operating efficiently during different ranges of wind speed. This allows energy generation at all times, even when winds are slight. The result of this process is an electrical current.
· This energy is either stored for later use, used directly.
There are two types of modern turbines-horizontal and vertical axis, both of which work similar to one another and as decried above. Between the two types, they come in an array of sizes from small 100 watt units for single homes to much larger or ones (with a blade diameter greater than 50m). These larger turbines can generate 1 MW of electricity.
The most common used today are horizontal axis turbines with three blades (15-30m in diameter) and produce approximately 50-350 kW of electricity. Often times wind turbines are grouped together; the arrangement in called a wind farm that provides energy to an electrical grid.
Vertical axis turbines are more efficient in areas with vast amount of lands and moderate wind speeds. Current technology is looking to develop different turbine types for different areas of wind speed given the amount of land available for farms.
General Advantages of Wind Power
The advantages of Wind power are many, including practical, environmental as well as economic.
Worldwide, the total kinetic energy contained in wind is more than 80 times that of human energy consumption. While only a fraction of this can be used for electricity purposes, the potential-given future technological developments-is great.
Environmental Advantages Renewable source of energy Clean, nonpolluting source of energy Curb the demand and use of fossil fuels Emit no air pollution of greenhouse gasses In CA, wind plants have offset the emission of than 2.5 billion pounds of carbon dioxide, and 15 million pounds of other pollutants
Economic Advantages--Wind energy is free! The cost of installation and maintenance has dramatically decreased in recent years. Future technology ensures only a continual decrease in the prices. No fuel to purchase and low operating costs. As a result, the lifetime investment is much lower than most fossil-fuel systems. Under the 1978 PURPA, individuals can install a wind mill and the local energy company must buy the excess power produced.
One of the primary disadvantages to wind power is the natural variability of wind in any given locale. Indeed there are certain areas with extremely high average wind speeds, but in most places, wind exposure is quite variable. Wind energy can only be stored with a battery, otherwise it is not. In the latter case, not all energy demands can be met through the natural timing of winds. For these reasons, it may not be a viable option for some. One other disadvantage is the competition for other -more highly valued and profit generating-land uses.
Economic Disadvantages The initial investment is often higher than fossil fuel systems. The higher costs is mostly due to the machinery which is involves. Other costs include site preparation and installation.
Environmental drawbacks The primary environmental drawbacks to wind power are as follows:· Noise pollution via the rotor blades Aesthetic impacts ("visual pollution")· Bird deaths
It is important to keep in mind that many of these problems have been resolved with increasing technology. Avian mortality, however, is still being studied.
A Homeowners Guide to Wind Power
How do you know if wind energy is an option for you?
Wind resources a categorized by wind-power density classes, wherein 1 is the lowest and 7 is the highest. Good wind resources generally fall above a class 3 level, with an average annual wind speed of at least 13 mph. These areas are located in the Pacific Northwest, the Great Plains, the Appalachian Mountain Chain, and various different locations along the east coast and elsewhere.
What about Vermont? Is wind energy feasible in the Green Mountain State, and more specifically in and around Addison County?
· The DOE provides mapping of the United States for potential users of wind energy:
The Northeast Region
The Northeast region consists of Connecticut, Massachusetts, Rhode Island, Maine, New Hampshire, Vermont, New Jersey, New York, and Pennsylvania. The region's total population in 1980 of 49,136,000 represents approximately one-fourth of the nation's population. A large percentage of the people in the Northeast live in the corridor between Boston and Philadelphia, while large areas of northern Maine and upstate New York are quite sparsely populated. The major cities, rivers, lakes, and mountain ranges are shown in Map 3-20.
The topography varies dramatically throughout the Northeast. The Appalachian Mountains extend in a bank from northern Maine beyond the southern border of Pennsylvania. To the east of the mountains lie piedmont and coastal plain regions. West of the mountains the land becomes flatter as one approaches the Great Lakes. A large portion of the land area of the Northeast is composed of either hills or mountains or open hills and mountains, while large areas of Massachusetts, Rhode Island, Maine, and New York are plains containing hills. The only area of tablelands in the Northeast extends in an arc from the Hudson River valley, across central New York, and into northwestern Pennsylvania. Central and southern New Jersey contains the only true plains in the region.
Areas of class 3 or higher wind energy potential occur throughout much of the Northeast region. The primary areas of good wind energy resource are the Atlantic coast, the Great Lakes, and exposed hilltops, ridge crests, and mountain summits from Pennsylvania to Maine. Areas of highest wind energy potential (class 5 and 6) are the outer coastal areas such as Cape Cod and Nantucket Island, offshore areas of Lake Ontario and Lake Erie, and the higher mountain summits of the Appalachians. Winter is the season of maximum wind power throughout the Northeast region. During this season, all except the most sheltered areas have class 3 or better wind resource, and exposed coastal areas and mountain summits can expect class 6 or 7 wind resource. In summer, the season of minimum wind power, class 3 wind resource can be found only on the outer coastal areas and highest mountain summits.
Major areas of wind resource in the Northeast region are described below. Maps of annual average wind power are presented in Maps 3-21 through 3-26 for Connecticut, Massachusetts and Rhode Island (displayed on one map), Maine, New Hampshire and Vermont (displayed on one map), New Jersey, New York, and Pennsylvania.
**This a map showing annual average wind power greater than 3 all along Vermont's eastern and middle regions. The range is from 3 to 5-indicating that wind power is indeed possible in Middlebury.
Another point made about wind power is that a wind farm or even a few turbines can share agricultural land uses. Grazing, for example, can continue to take place in the presence of a wind farm.
Small Wind Energy systems can be used in connection with (i.e./ supplementing the energy grid) or as stand-alone applications which are independent of the energy grid. One can choose between these two options based on the following criteria provided by http://www.eren.doe.gov/wind/homeowner.html
Conditions for stand-alone systems
· You live in an area with average annual wind speeds of at least 4.0 meters per second (9 miles per hour)
· A grid connection is not available or can only be made through an expensive extension. The cost of running a power line to a remote site to connect with the utility grid can be prohibitive, ranging from $15,000 to more than $50,000 per mile, depending on terrain.
· You have an interest in gaining energy independence from the utility
· You would like to reduce the environmental impact of electricity production
· You acknowledge the intermittent nature of wind power and have a strategy for using intermittent resources to meet your power needs
Conditions for grid-connected systems
· You live in an area with average annual wind speeds of at least 4.5 meters per second (10 miles per hour).
· Utility-supplied electricity is expensive in your area (about 10 to 15 cents per kilowatt-hour).
· The utility's requirements for connecting your system to its grid are not prohibitively expensive.
· Local building codes or covenants allow you to legally erect a wind turbine on your property.
· You are comfortable with long-term investments.
Before one decides on wind power, one must do a series of site specific spots. Even within the same property, there can be better places to harness the wind than others can.
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