Environmental Engineering Reference
In-Depth Information
Land Requirements
Land area used for the turbines in a wind power station is small, with unoccupied land
available for other compatible uses. Dedicated land actually occupied by the wind turbines,
the connecting roads, and the plant infrastructure is only 2 to 5 percent of the total station
area. The area surrounding the turbines is available for agriculture, forestry, fishing, or other
commercial uses. Midwest farmers have found that revenues per acre from wind plants often
exceed that for crops without effecting normal agricultural production.
In a DOE study to support a scenario in which 20 percent of the U.S. electricity demand
would be supplied by wind power stations in 2030, a total wind power capacity of 305 GW
was projected [DOE 2008]. Of this, 24 GW would be located on land-based stations and 54
GW in shallow water offshore. To meet that 20 percent goal, new land-based installations
would require approximately 50,000 km
2
of land. However, the actual footprint of land-based
turbines and related infrastructure would require only about ,000 to 2,500 km
2
of dedicated
land—slightly less than the area of Rhode Island. According to the conclusions of this study,
available land area is clearly not a limiting factor in meeting and even doubling the 20 percent
estimate.
Land costs are usually reflected in operating expenses. Land for wind power stations
is generally leased to the developer or operator, although in some cases the developer may
buy the site. Lease terms often include a one-time, advance payment of $200 to $2,000 per
turbine (in 2008 dollars) plus a royalty or percentage of earnings from electricity sales. The
royalty may be calculated on either gross or net earnings. Such fees have generally been 2 to
4 percent of net revenues.
Critics of wind power stations have raised concerns about visual pollution, noise, avian
and bat impacts, and other land-use issues. While questions of aesthetic and noise impacts
arise with the installation of all energy facilities, in other ways the land-use requirements for
wind power stations are unique. Developers must place the turbines in geometric patterns
to optimize the land use while minimizing the wake interference from upwind turbines on
downwind machines. These patterns depend upon the terrain and the prevailing winds. In
ridgeline installations turbines can be seen from greater distances, and often the land owners
that have to look at the turbines are not those receiving revenues. Offshore installations can
be seen for even greater distances and there is pressure to place installations out of sight of
land, up to 20 km from shore. Experience has shown that aesthetic objections diminish as
wind plants become more common and their environmental benefits are recognized.
Wind Turbine Size Factors
The trend in commercial sector has been to produce wind turbines with ratings of either
less than 00 kW or more than MW. For offshore applications, where transportation of
very large and heavy components is not a limiting factor, turbines with rotors up to 20 m
diameter and ratings of 7 MW are now being developed. Since 998 average turbine size has
increased 30 percent. In 2007, 40 percent of the turbines installed in wind power stations
had rated capacities larger than .5 MW, compared to only 3 percent in 2002 and 2003.
Machine sizes are expected to continue to increase, but at some point the transportation limi-
tations on components for land-based systems are expected to become a firm barrier.
Variability of Electrical Output of Wind Power Stations
Grid integration studies have generally concluded that large-scale wind deployment does
not have negative impacts at penetration levels less than 0 to 5 percent. Even at 30 percent
or higher wind penetration power regulation, impacts are expected to be small. An example
Search WWH ::
Custom Search