Most coal-fired power plants are at least as old as I am. But I never spew mercury into the air.
The Energy Information Administration published a couple of charts that have the energy/environment blogosphere talking. Above, see the amount and source of energy that came online in the United States by year. The ‘50s, ‘60s, ‘70s and ‘80s saw tons of coal plants built. Not a ton after that thanks, as Brad Plumer wrote, to cost, regulation, and advocacy.
It’s a cool chart from a historical standpoint: Here, it says, is when we stopped believing in coal—at least, when we stopped believing in it enough to keep building coal plants. But another EIA document shows that although we haven’t been building a lot of new coal plants lately, we’ve still been burning about the same amount of it each year since 1987. That means that we’re still paying for it—in a number of ways—every year.
More recently, we clearly see evidence of what Andrew Revkin called the "gas age." And while some of us might feel a little giddy about that (because it's not, for example, mountaintop removal mining), natural gas of course has its own external costs, too—most famously, those of fracking. You can also see a smaller spike in wind power production.
Below, we see the age of our electric generators by type—just a different way of looking at the same information.