“…In particular, GREET estimated the energy efficiency of gasoline at 80.5 percent; 84.3 percent for diesel fuel; 89.8 percent for LPG; 94.0 percent for natural gas; and 98.0 percent for coal (Shapouri et al, 2002). Boiler efficiency of 80 percent was used for the steam production (Ahmed et al, 1994) and the conversion efficiency of 70 percent was used for methanol production from natural gas (Kiso and Arashi, 1998). All estimates of electricity generation were based on weighted average of all sources of power used in the United States, including coal, natural gas, nuclear, and hydroelectric.…”