Ray Mabus, Secretary of the U.S. Navy, has a refreshing historical perspective on the Navy's efforts to end its dependence on our increasingly expensive and environmentally destructive supplies of oil. From a speech he recently gave at the National Clean Energy Summit 4.0:

In the 1850s, we went from sail to coal. In the early 19th century, we went from coal to oil, and in the 1950s, we pioneered nuclear.

Every single time, there were people that said, “Can’t do it. You’re changing one very certain means of transportation for one that is not that certain,” and every time, those naysayers were wrong.

Mabus isn't just talking a good game here – the Navy has committed billions to its goal to reduce its consumption of conventional oil. That includes the Navy's first hybrid ship, the USS Makin Island, an amphibious assault vessel. On the Makin Island’s first voyage, it saved $2 million in fuel costs, says Mabus.