Mining is the second most dangerous profession in the U.S., averaging 27 deaths for every 100,000 workers per year, according to the U.S. Census Bureau. That safety record is now blown. On April 5th, 25 of the roughly 20,000 miners in West Virginia died in a tragic incident at the Upper Big Branch mine. Four remained missing as of Friday.  

The explosion appears to have been caused by a buildup of methane . An odorless, colorless, tasteless gas that you know as natural gas. It explodes at concentrations in the air of as little as 5 percent. The incident also could have been caused or exacerbated by coal dust, which is equally combustible. That's why we burn it to make electricity.  

[ This special issue podcast is longer than the usual 60 seconds. ]

Last week, the new Advanced Research Projects Agency for energy held its inaugural conference in Washington, D.C.--a direct response to a growing sense that the U.S. is losing its technology lead when it comes to the race for cleaner ways to produce and use energy. "We have a Sputnik moment right now. We are losing our technology leadership and we are falling behind."

[ Below is the original script. But a few changes may have been made during the recording of this audio podcast. ]

Homes are rising on the National Mall in Washington, D.C. No, it's not a return of Hoovervilles thanks to the Great Recession. These are solar homes competing in the U.S. Department of Energy's Solar Decathlon , which starts October 8.