The Army has a large array of vehicles and equipment to use. However, they all need to be powered in some manner. For example, the popular M1A2 Abrams tank is an effective, but thirsty machine. It consumes 500 gallons of fuel with an movement range of 256 miles.
Even the popular Humvee is a energy consuming giant. Even though it has a 25 gallon fuel tank, it is used repetitively, taking up gasoline on a large scale. With a top speed of 70 miles per hour, it weighs between 5,200 and 5,900 pounds of metal and armor.