"McCain and other opponents of the program have seized on the fact that the Navy paid more than $26 a gallon for the biofuels it purchased for this week's Green Fleet demonstration, compared with less than $4 a gallon for convention fuel.
The Navy has noted that the 50-50 mix of biofuel and petroleum-based fuels, formulated as a "drop-in" blend requiring no modification to aircraft or ship engines, cost a combined $15 a gallon. Most of the biofuel half of the mixture, about 90 percent, was rendered from cooking oil waste. The other 10 percent was refined from algae."