This is one of the reasons why I'm not very optimistic for environmentalism. People's needs and wants are sort of like gasses: they expand to fill the space they're in. More efficient engines in cars often just mean they're a tiny bit more efficient and significantly faster than they actually need to be. (rather than significantly more efficient and relatively slow) Modern computers are incredibly fast, but we just keep making webpages heavier, and operating systems heavier. So although many modern computers are quite efficient when considering speed to power consumption, they could use significantly less power, except for the fact that people are always chasing the next thing.

We eat up our new efficiencies the moment we invent them.