During its first few years, funding was of the utmost importance for Clean Energy Fuels (NASDAQ:CLNE). If the proposed stock sale by Chesapeake Energy (NYSE:CHK) had happened back then, it might have spelled doom for the nascent business. Now, however, some of the biggest companies in the world are buying into Clean Energy's vision for a cleaner driving America.

Just recently, FedEx (NYSE:FDX) CEO Frederick Smith professed that he sees a major shift for fleet vehicles toward liquified or compressed natural gas over the next 10 years. This support is huge given FedEx's fleet of around 90,000 vehicles. He was also outspoken about the need for the U.S. to approve exports of LNG, one of the few CEO proponents not employed by the energy sector. 

More details can be found in the video below.