Wind power rarely occurs where it is needed most. Conversely, you would not want to live where the wind is always fierce, like the west side of the Falkland Islands. New transmission lines are necessary, and this obstacle is preventing wind power from developing as fast as planned. In Germany alone, it is estimated that 2,700 km (1,700 miles) of extra-high-voltage lines will be needed by 2020 to carry an expected 48 GW of wind power. These lines run at up to 380 kV, compared to high-voltage lines at 110 kV, which are scary enough, and will cost over 3 billion

Compressed Air _

Fig. 3.17 Compressed air energy storage scheme for wind power (Vestas Wind, No. 16, April 2009)

euros.11 Traditionally, power plants are built near population centers, so the transmis­sion lines are short. Distributing wind power will require new rights-of-way, some of it underground. These lines cost 7-10 times as much as standard lines.11 There will be political, legal, and social problems in addition to the large cost. Germany,

and even all of Europe, is small compared with the US. Transmission lines are an even bigger problem for wind power in the USA.

Load distribution is another big problem. If the wind input to the power grid varies by as much as 10%, the grid can become unstable. However, if several wind sources are connected to the same grid, load variation can be avoided if the power can be switched in and out fast enough from each of the sources. This requires accurate forecasting of the wind speed and close collaboration among grid opera­tors. The Nordic countries of Sweden, Norway, and Denmark are close enough to pool their resources for load leveling.18 They can exchange wind and hydro energy. For instance, when wind power is excessive in Denmark, it can sell the power to Norway. Norway can accommodate the power by slowing down its hydroelectric power, storing the energy in the reservoir above a dam. The hydro energy can be sold back to Denmark when the wind dies down.

Wind is so variable that it can never be a large fraction of the total grid power. Not only that, but it must be backed up by conventional fossil fuel or nuclear plants. Estimates vary from 90%11 to 100%.24 That is, for every megawatt of new wind power installed, one megawatt’s worth of new coal, oil, gas, or nuclear plants have to be built.