Stanton worked closely with Hahna Alexander, a fellow Carnegie Mellon University engineering student, over three years to create the SolePower system. Instead of using piezoelectric and other inefficient, bulky methods of generating electricity, the pair shrunk down components similar to those found in hand-cranked flashlights. The result is a near standard-size removable insole that weighs less than five ounces, including a battery pack, and charges electronics via USB.

At the end of his road trip on Monday, Norman Hajjar had used a little more than 4,000 kilowatt-hours of energy. He drove a Tesla Model S sedan for 12,000 miles over 24 days, crossing 27 states along the way.

The great Scottish scientist James Clerk Maxwell wrote in 1874 to a colleague: “I saw conductivity of Selenium as affected by light. It is most sudden. Effect of a copper heater insensible. That of the sun great.”

In the next few years, the stale, thick heat produced by the London underground will no longer drift uselessly into the atmosphere. Instead, some of it will warm 1,400 nearby homes, cutting heating bills by about 10 percent. Recycling heat is quite common in Europe. Denmark gets roughly half of its electricity from recycled heat, followed by Finland at 39 percent, and Russia at 31 percent. In the U.S., it’s just 12 per cent.

Solar power has proven itself better for static charging than it has for on-vehicle use, even if Australia's Solar Challenge race has shown solar cars to be possible under certain, very specific conditions.

Suddenly, hydrogen fuel-cell cars are back in the news. Headlines have proclaimed a coming battle between plug-in electric cars and the new shining hope, hydrogen-powered vehicles.