In spite of the vision of Al Gore and others, windmills cannot be expected to supply a major part of our energy demands. For a good discussion of the problem with wind and other forms of green energy, see The Wrong Way to Get to Green, by Robert Bryce.
According to Bryce, windmills require 45 times as much land as nuclear power to produce the same amount of energy. Wind farms tend to be located far from population centers and so would require hundreds of miles of additional power lines to reach consumers. When you add up the land, new power lines, and the concrete and steel and other inputs required to build and operate a windmill, the expense per megawatt of electricity is higher than for most other sources of power. And not only is it expensive, but wind power is often unavailable on the hottest days of summer when energy demand is greatest.
Besides the high cost of land and materials required, wind energy is costly in terms of its impact on the environment. Windmills and the new high voltage lines associated with them kill birds, disfigure the landscape and create noise that irritates nearby residents.
For the above reasons, the government should stop subsidizing and pressuring utilities to use wind energy and let the market determine how viable it is. Wind might be cost effective in some locations, but it is not economically viable on a large scale. The greater the share of electricity in a grid that is generated by wind, the higher the cost. This is because standby generating capacity from other sources must be maintained to meet demand on some days when their is little wind. Existing sources of electricity like oil, natural gas, nuclear, and coal are much more reliable and less costly than wind, even when environmental costs are accounted for.
Without subsidies and mandates requiring a specified percentage of electricity to be generated from renewable sources, utilities would only use wind and other forms of renewable energy if they were cost effective. Some argue for subsidies to renewable energy sources because they claim that conventional sources of electricity are subsidized either through tax breaks or by not having to pay for the pollution they cause. If this is the case, the solution is to eliminate subsidies and make sure that utilities pay the full cost for each source of power they use. Market prices will give utilities and their consumers the correct signal about the scarcity of the resources involved in producing electricity, thus motivating utilities to economize in choosing how to generate electricity and motivating consumers to economize in choosing how much electricity to consume.