A graphite disk resting on carbon foam collects sunlight to heat water directly to steam with 85 percent efficiency. Cynthia Graber reports 

 
Learn more about your ad choices. Visit megaphone.fm/adchoices

A graphite disk resting on carbon foam collects sunlight to heat water directly to steam with 85 percent efficiency. Cynthia Graber reports 



 

Learn more about your ad choices. Visit megaphone.fm/adchoices