Kevin Bullis of MIT Technology Review does a very nice thing today for celebrating the Fourth of July. He charts how American energy consumption has changed since 1776. If you imagine it as an animated graphic going off from left to right, it looks like a fireworks display. In fact the lines have that trailing quality where one rocket explodes, followed by another and then another.
The first to go off was coal, around 1895. It climbed to a certain height around the 1920s, then tailed off as oil and natural gas began to replace it in electric and steam engine boilers. Then it got another boost after the Oil Crisis of the 1970s, when we stopped burning oil for electricity.
Petroleum has been the main show since the 1920s, soaring to the highest levels in the 1960s, falling back after the Arab Oil Boycott, but then making another recovery to its highest point ever just before the recent recession. The graph doesn't really catch the latest upsurge in domestic production and oil may be poised for another rebound if the economy ever picks up again.
Natural gas followed oil up the curve, descended in the same way in the 1970s, and then picked up again. Only in the last few years, with the invention of fracking, has the old oil-gas link been broken. Natural gas is now ascending even as everything else but renewables is descending. There is some speculation that it could eventually pass petroleum if we ever learn to use it in cars. (See Fuel Freedom Foundation.)
Hydroelectricity has played a smaller part than might be imagined. There was a big dam-building surge after the invention of grid electricity and the Army Corps of Engineers kept up a steady drumbeat until running into environmental opposition in the 1970s. But there are only so many good dam sites and hydro's contribution has pretty much levels out.
Nuclear's rocket sent off in the 1970s and it looked like it was headed even higher. But opposition hardened, construction ended and most of the gains in the last two decades have come from improved operation of existing reactors. Only in the last year has nuclear's contribution dipped a bit as older reactors close and competition comes from cheap natural gas.
Wood has played perhaps the most interesting role. It was our sole source of energy - besides human labor - until the Civil War. Then as fossil fuels entered it went into a slow, steady decline until undergoing a recent revival with the return to wood stoves. Today the contribution is not all that different than in 1776.
Finally there is renewable energy, mainly windmills and solar power. They have undergone a mini-surge in the last ten years. Interestingly, as Bullis points out, renewables now provide more energy than the entire country consumed in the 1800s. They will surely be adding more, especially as rooftop solar installations become cheaper and more accessible.
In 1776, the only thing that lit the night sky was the campfires of George Washington's army as he gathered his troops in Brooklyn waiting for the British invasion. Today the whole American sky is illuminated with a myriad of energy sources. But if