On a global scale, we humans are becoming more energy efficient with each passing year. Even so, we’re exploiting only a fraction of the technological opportunities to use energy more cost-effectively. There’s a lot governments can do to put this right. Worldwide, the amount of energy employed to produce a unit of gross domestic product fell by 0.4 percent a year from 2000 to 2010, according to the International Energy Agency . Last year and the year before, the annual decline accelerated to 1.5 percent. Looking ahead 20 years, though, the IEA (in effect, a club of energy ministers) estimates that two-thirds of the potential for energy efficiency will remain unexploited. Capturing a good part of this potential wouldn’t be technically difficult. Proven cost-effective technologies, and others in the pipeline (if you’ll forgive the expression), could reduce the expected growth in energy demand by as much as 50 percent […]