installing addition natural gas peaking power the costs will increase very significantly.   These increased cost factors will further increase the average future power costs by probably another 2 cents per KWH.  This added expense further increases the cost burden on the average U.S. Household for substantially reducing U.S. CO2 emissions in the future. willem Post said: John, "In most cases as long as the new replacement turbines are installed on existing wind turbine structures/foundations and reuse existing infrastructures, the cost should be a fraction of new grass root wind turbine installations." Just changing out a gearbox on a 3 MW IWT costs about $500,000 to $600,000, not counting non-productive down time. Newer IWTs do not have gearboxes, but use thousands of pounds of rare earth metals from China. To have 25% of US wind energy by 2062, 50 years, installation rates would be 180,000 MW per decade, or 18,000 MW per year, during the first 20 years and then 36,000 MW per year, new-built plus replacement, thereafter. These MW quantities include downtime of IWTs for scheduled and unscheduled outages. Note: The US maximum new-built rate was about 10,000 MW in one year. It will be less expensive to take the whole unit off the mast and rebuild it on an assembly line in factories located where there are wind turbines. Offshore will be a special challenge. With setbacks of about 2 km, large areas of the US would become unfit for human habitation. Birdlife, already greatly reduced due to modernity