Natural gas has experienced a surge in the U.S. energy sector, accounting for more than 25% of the total amount of energy used in the U.S. in 2009, though during that same year it accounted for less than 3% of the total energy used in the transportation sector. For a vehicle to operate on natural gas, it must be outfitted to use either a highly pressurized form of gas known as compressed natural gas (CNG) or a liquid form called liquefied natural gas (LNG). CNG technology is best suited for return-to-base scenarios where vehicles refuel daily. Case studies in the literature have examined the feasibility of operating municipal fleets on CNG. The objective of this thesis is to evaluate the conditions under which it would be economically profitable for a private regional shipping company to outfit their fleet to operate on CNG as opposed to conventional diesel.