According to the Energy Information Agency, coal was used to generate 1.58 million thousand megawatt hours of electricity in 2013. These plants had a combined total nominal capacity of about 340 gigawatts. The cost of solar cells is dropping rapidly and is approaching $1 per watt installed capacity. That means it would cost $340 billion to install enough solar cell arrays to replace all of the coal-fired power plants in the U.S. (approximately 1500 power plants).
Yes, that is a doable number.
But, what about area? Surely, that many solar arrays would take up a lot of land.
Using a figure of .556 m2 per 180 watts ofcapacity, we would need about 1 billion square meters of arrays. That is about 400 square miles. Including space between arrays and room to operate, let's say it roughly 1000 square miles. Using a standard measure of area, that is less than the area of Rhode Island (1200 square miles). To put it another way, it would be a square 32 miles on each side.
Again, this is certainly feasible - especially considering the total area of the coal fired power plants would be available for conversion.
What about operating expenses?
The average cost to operate a coal-fire power plant is around $7 per megawatt hour = $11 billion per year (using the 1.58 million thousand megawatt hours figure quoted above). Total operating expenses for solar = $0.
Once again, solar compares very favorably.
What about public safety?
Coal is the number one source of mercury in the air and water; the number one source of arsenic in the air and water; the number one source of sulfur dioxide which causes acid rain; the number one manmade source of radioactive particles in the air (coal is usually radioactive); the number one manmade source particulate matter in the air (leading to a whole host of health problems); and, oh yeah, the number one source of carbon dioxide emissions causing manmade global warming.
Solar? No emissions.
Solar certainly comes out a head on that one.
In summary, even using rough numbers, we find the cost of replacing coal-fire power plants with solar power is reasonable; the land requirements are minimal; the operating expenses are much lower for solar; and the health benefits from getting rid of coal-fired plants are enormous. In short, it is very feasible to replace all coal-fired power plants with solar cells in even the short-term.
So, why aren't we?