[alexbock]

Not very much, the 15-inch has a 76 Watt-hour battery [1] and putting 152 of those into Wolfram Alpha gives less energy than a gallon of gasoline [2].

[1] http://www.apple.com/macbook-pro/specs/ [2] http://www.wolframalpha.com/input/?i=76+watt+hours+in+tons+o...