If you look at renewables as a share of the total sources of energy in the U.S., it's more than doubled in the last 10 or so years. And that's really impressive, especially when you consider during that time, most renewables, at least on pure price, were more expensive than what they compete against—coal or natural gas. So, the fact that they were able to grow so remarkably in that period of time, even though they're in some ways more expensive than what they're competing against; it tells you that something important was going on.

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