Tudor Van Hampton Energy Secretary Chu speaks at the Green Truck Summit, held at this year's Work Truck Show. Tudor Van Hampton Commercial fleets have adopted CNG and propane more than any other alternative fuel, according to NTEA. Related Links: Concrete Mixer Saves Money With Natural Gas DOE's Chu Defends Decision to Support Solyndra Natural gas is "no longer a debate" for fueling commercial vehicle fleets, said U.S. Dept. of Energy Secretary Steven Chu at this year's Green Truck Summit, which opened March 5 in Indianapolis.Chu likened America's fuel crisis to a beef-eater who can no longer afford to buy
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.