1.3 Billion Wind Turbines Needed to Replace Coal

McFadden Ridge Wind Project

Tennessee wind turbines similar to McFadden Ridge
Tennessee wind turbines similar to McFadden Ridge

Construction of Rocky Mountain Power’s McFadden Ridge I wind project is underway in Albany County, Wyoming, near the towns of McFadden and Rock River. The project consists of 19 General Electric wind turbines, capable of generating a combined 28.5 megawatts of electricity.

See the Update section at the end of this post for a recalculation of the number of wind turbines needed to replace coal.

1.3 Billion Wind Turbines Needed

Now for a little back-of-the-envelope math. The McFadden Ridge project has 19 wind turbines producing 28.5 megawatts of electricity. Each wind generator therefore produces 1.5 megawatts. In the United States in 2007 coal was responsible for generating 2,016,456 gigawatts of power (see USA Electricity Generation 2007 Chart). As 1 gigawatt equals 1,000 megawatts you would need 1.3 billion (2,016,456,000 megawatts / 1.5) wind turbines to replace coal. And coal only accounts for 48% of electricity production.

651 Million More Wind Turbines

Petroleum liquids (49,505,000 megawatts), petroleum coke (16,234,000 megawatts), natural gas (896,590,000 megawatts), and other gases (13,453,000 megawatts) account for a total of 975,782,000 megawatts. To replace these sources of power you would need an additional 650,521,333 wind turbines. In these calculations we are not replacing the 21% of electricity generated from nuclear power. Even so, removing fossil fuels from the equation mandates the need for 2 billion wind turbines. And remember, wind power costs twice as much as electricity from coal.

Growing Electricity Needs

Rocky Mountain Power says:

To meet the growing electricity needs of its customers, Rocky Mountain Power is investing in new generation, transmission and distribution facilities in Wyoming and other states, as well as purchasing the output from wind projects owned by other entities.

These wind projects are to meet the growing electricity needs of its customers, not to replace coal generating plants. Construction of the McFadden Ridge I wind project is not even included in the 2 billion number cited. The wind turbines being constructed today are to meet growing demand, some of which will be met by even more expensive solar power. I would be very careful about trusting politicians that want to eliminate fossil fuels without giving an explanation of how we are going to replace them with the needed 2 billion wind turbines.

But whatever happens, please don’t put me in charge of turbine maintenance.


A co-worker, Josh, pointed out to me that my calculations were wrong. First the 1.5 megawatts output of the wind turbine needs to be multiplied by the number of hours in a year. Then the ratio of the maximum possible output to the typical output, called the capacity factor, needs to be calculated. For our purposes I will use a capacity factor of 30%. So now we arrive at the following:

1.5 megawatts x 24 hours x 365 days x 0.3 capacity factor = 3,942 megawatt hours.

Now with a more realistic divisor we arrive at the number of wind turbines needed to replace coal:

2,016,456,000 megawatt hours / 3,942 megawatt hours = 511,531 wind turbines.

I still don’t want to be in charge of turbine maintenance.

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This list is updated occasionally, with newer additions listed first.