Why is hydroelectric power only practical in certain places?

Yes, it can and is being done, but does anybody have a $/kw figure?

We have an unlimited supply of free power. All we need is the money to collect it.

I hope I am not straying too far off topic to give some figures. The 11 April Forbes has an article on Japan recovering from their disasters. It includes some figures on what it would cost to replace the power from the atomic plants.

Solar parabolic troughs covering 80,000 acres
$ 40 billion
Wind 6,000 turbines covering 100,000 acres
$18 billion
Coal 15 modern coal-fired power plants
30 billion Natural gas 8 modern combined cycle power plants 7 billion
Nuclear 6 new reactors
$ 24 billion

I am surprised how well wind fares, second only to natural gas with its high fuel costs. We can build wind cheaper than coal?

I am sure the Japanese will be forced to select choices minimizing land usage. Can you imagine Mount Fugi ringed with wind turbines?

Perhaps we need to think more about wind. I have imagined a turbine at the top of every high tension tower. The electric company already owns the land, easy to connect to the grid, and it can’t be much more of an eyesore. Likely the towers aren’t built to support the additional loads.

We have the space, and mostly need power on hot summer afternoons, often windy times. I find it unlikely that New Mexico, Wyoming, and off shore Maine would frequently be becalmed at the same time. They do grind up birds. They work although the wind is free to go around them.