"Washington is the greenest state, according to our scoring system. It stands out for its significantly higher conventional hydroelectric power generation and overall renewable energy production."

Obviously, most states cannot generate as much hydroelectric power as Washington. Also, the states with "dirty" energy may be producing food and manufactured goods consumed in the "clean" states.

This is true, though lots more places could have hydropower than do, and presumably all of them could have as much nuclear as demand required.