Source: National Renewable Energy Laboratory Photographic Information eXchange
Europeans used the kinetic energy in wind to sail to Virginia for 400 years, from the 1500's into the 1900's. Since those Europeans settled Virginia successfully in 1607, rural Virginians have used windpower to pull water up from wells - long before electrical lines connected farms to the "grid" and powered modern pumps. In some cases, wind power was also harnessed in Virginia to power manufacturing facilities, such as mills that ground wheat into flour. Pumping and powering grist mills required that the windmill be located directly next to the facility - gears and belts could not transmit the mechanical energy more than about 100 feet.
Today, almost all labor-saving devices in the home, office, or manufacturing plants operate off electricity that can be generated far away from the site where the power is used. A handful of existing wind turbines convert wind energy to electrical energy, including one 10 kW turbine at the Smith Mountain Lake Visitor Center:
More wind-powered turbines are planned in the mountainous regions of Virginia, or in the Atlantic Ocean east of the shoreline. Demand for more electricity is expected to increase along with the state's population. As more people are born in or move to Virginia, total demand for electricity in Virginia will climb - even if conservation efforts ultimately reduce demand/person.
The one-time infrastructure costs of building turbines and electrical transmission lines in remote areas is high, but the annual cost for fuel (wind...) is free. Even though electricity generated by wind costs more than electricity generated from coal, hydropwer, or nuclear facilities, there are still customers for wind-generated electricity.
In addition to Federal tax advantages, some states are adopting Renewable Portfolio Standards that mandate a certain percentage of electricity generated or purchased within the state come from renewable sources, and urban regions with air quality problems (like Metropolitan Washington) are trying to get credit for purchasing "green power" to meet Clean Air Act standards. (Virginia has suggested, but not mandatory, Renewable Portfolio Standards in the 2007 Virginia Energy Plan.)
Ridgetops in the Blue Ridge, Ridge and Valley, and Appalachian Plateau physiographic provinces - and the open water region off the Outer Continental Shelf - are clearly the areas with Class 3 and higher winds that could power a modern turbine. The Piedmont and the Coastal Plain have few locations with high wind potential. The greatest potential for generating electricity from wind energy in Virginia is to locate turbines in the mountains (especially Highland County) and offshore (east of the Eastern Shore/Virginia Beach).
Utilities seeking to generate electricity for sale look for at least Class 3 or higher zones, where wind speeds exceed 12.5 mph. (Wind power maps often show speeds measuring "wind density," where Class 3 speeds are about 15 mph. Wind density accounts for the decline in atmospheric density at higher elevation; thinner air generates less power when pushing against a turbine blade.)
The energy potential of a wind turbine increases dramatically as wind speed increases. The maximum energy output of a turbine at full speed is far greater than the likely production at average speeds... and the wind does not blow 24 hours/day, either.
Wind energy is often measured at 50 meters (164 feet) above the ground. Wind speed next to the ground is reduced by friction with vegetation and the surface of the ground. In engineering terms, "there is often a layer of high wind shear between 10 and 50 m height above ground due to the influence of trees."1
To maximize wind speed that turns blades, windmills involve tall towers. If a turbine blade can be extended on a tower as much as 400 feet above the ground, the wind currents will be faster and steadier. A tall windmill has greater potential to convert wind energy into electrical energy, and produce more electricity at a lower cost. However, a tall windmill will also be more visible from a distance, so wind energy projects involve scenic impacts. Raising turbine blades far above trees on towers 150-400 feet tall increases the potential windpower that could be captured... but makes the turbines very obvious intrusions on top of forested mountain ridges. In addition, new transmission lines will require cutting new swaths through the forests, creating visual scars.
The Virginia Wind Resource Map summarizes the wind potential of the state at 50 meters above the ground:2
Offshore locations are atttractive locations physically because there are no forests, no trees to slow down the breeze. Wind energy projects can be located according to financial and political reasons, as well as by simple physical geography. From a venture capitalist point of view, the ownership and permitting issues are also significant. Turbines are not cheap, and "time is money," so investors look for places where the delays in getting authorization to build will be minimized. Offshore, companies can negotiate with just state/Federal governments to get rights to build towers with turbines.
There are no private landowners offshore, no land to lease or buy. Instead, Federal permits must be obtained from the Department of the Interior - Mineral Management Service. Previously the Corps of Engineers issued the permits, in order to manage the creation of new obstructions to navigation. Now MMS has the responsibility, reflecting their offshore responsibilities for oil and gas drilling and mining from the ocean seafloor.
Federal permits require an environmental analysis and a public comment process. The request for a Federal permit near Nantucket Island in Massachusetts became a hot political issue in 2005-2006, and the US Congress slowed down the proposed offshore wind farm there.
Siting a wind farm off the Virginia coast is a complex challenge. All proposals for wind farms in ocean waters create potential conflicts with shipping along the coast. In addition, military radars on the coastline may be affected by wind turbine blades, though some companies are developing "stealth" turbines that would not block radar signals. An offshore wind farm near Virginia Beach/Norfolk would be closer to the market for the electricity than one located off Chincoteague, reducing costs for underwater transmission lines - but would have more conflicts with shipping going in/out of the Chesapeake Bay.
On land, the taller mountain ridges in Virginia are the most attractive locations for electricity-producing wind tubines. Wind speed on the ridges is usually higher than in the valleys. Because the jet stream typically flows north of Virginia, windmills are feasible on low ridges in the northern part of the state. The closer to the North Carolina border, the higher the Virginia ridge must be to intercept strong and steady winds in all four seasons of the year:3
Most wind energy projects in the mountains are located on private lands. Energy companies would rather pay a private landowner and go through a county planning process than request a permit from the USDA-Forest Service to place turbines on National Forest lands. (Wind energy projects intended to generate power for sale must also get a certificate from the State Corporation Commission.) Those Federal forests have existing stakeholders and land use plans that defined primary uses for specific areas, and changing the designated uses to include wind turbines is a difficult process.
In November, 2002, Winergy LLC proposed to build 271 wind turbines in the Atlantic Ocean, east of Accomack County at a site called Porpoise Banks 2. The company proposed to build enough turbines to generate 975 megawatts/hour, equivalent to the output from a nuclear power plant. When the Army Corps of Engineers advised that the location was sensitive to the military, Winergy shifted its area of interest to the ocean east of Smith Island, at the southern tip of the Eastern Shore.
However, all proposals for wind farms offshore from the Virginia coast remain just proposals, with no operating turbines. Locating turbines out of sight, offshore of the Atlantic coastline of Virginia, does not eliminate siting conflicts.
In addition to the constraints of finding a location in Virginia with sufficient energy to power turbines, two environmental constraints limit the potential location of new wind energy farms - the visual impacts of the towers and blades, and tendency of the blades to kill birds and bats migrating through the area. Turbines could be "bird Cuisinarts," when a flock migrates through a wind farm. The Eastern Shore is a major stopping point on the Atlantic Flyway, and the Federal government must consider the potential impact on migratory birds before granting a permit for an offshore wind farm.
Birds and bats are threatened by onshore wind farms as well. A proposal in 2005 to build turbines on a ridge in Highland County exposed the conflicts between tourism-based businesses and the those who support wind farms. One article in the local paper noted that Federal mandates for utilities to generate a certain percentage of their electricity from renewable sources (renewable portfolio standards or "RPS") would stimulate wind power projects, but some states are "wind poor."
Even within a state that has the climate and topography to generate a lot of wind energy, the locations for windmills are often in rural areas - requiring unsightly power lines to the urban areas creating the demand for power. As discussed in the Congressional debate:5
In early 2006, Community Energy, Inc. revealed its interest in building a wind farm in Patrick County. As described in The Roanoke Times:6
Geographic Information System (GIS) technology can be used to identify environmentally-sensitive locations that would stimulate objections to a proposed wind energy "farm" of multiple turbines - see A Landscape Classification System for Virginia. Here is a sample map from that report:
