Another reader chimes in on wind:
Your reader got a little carried away with his defense of wind. Comparing the cost of the output from a 30 percent available, un-schedulable generator with the cost of power from a 90 percent available, schedulable generator is fine, as far as it goes. If wind is strictly “source of opportunity” power, used when it is available and replaced by conventional power when it is not available, its value is substantially lower than its apparent cost.
However, if wind is treated as capacity, rather than commodity, achieving 90 percent availability of the output of one wind turbine requires the installation of 6 wind turbines of 30 percent availability in 6 geographically dispersed locations which have a very low likelihood of being impacted by the same weather events. While the 6 wind turbines will produce about twice as much power as the reliable portion, the excess power is un-schedulable and thus of lower value.
The availability of large capacity, rapid in /rapid out storage would reduce the number of wind turbines required, but probably not the total system cost.