Could railroads, the oldest form of mechanized mass transportation, be the key to unlocking solutions to some of the greatest challenges of the 21st century? Unique among modes of long-haul transport, rail can be electrified. So, why not power trains with renewable energy? Might a clean, modernized, higher-speed rail network draw freight and passengers off the highways and back onto the tracks? Could electrifying the railroads actually open new transmission corridors and increase the supply and reliability of electricity from wind and solar? If the rest of the world is already electrifying...