12. Heat, Energy, and Chemical        Bonds   Previous PageNext Page
       Fuels, Combustion, and Energy

The one big advantage of fats over gasoline is that fats are solids. It would be almost as disadvantageous for us to carry around liquid gasoline as an energy reserve as it would be to carry huge gas bags of hydrogen. (An organism that evolved bags of hydrogen gas for energy storage also would have come a long way in solving its locomotion problem. But thunderstorms and lightning would be hard on such a creature.)

Even animals cannot get along without the rapid-access feature of starch as an energy-storage agent. Animals have glycogen in their bloodstream as a quick-energy source, which serves as a buffer between the immediate energy needs of the organism and the slow production of energy from fats. Glycogen, or "animal starch," is a branched-chain polymer of glucose molecules very similar to plant starch.

The table of heats of combustion on page 14 also points out that we could do much better than to burn our fuels in oxygen. Combustion of methane in 02 produces only 13 kcal of heat per mole of methane, whereas combustion in F2 would yield 25 kcal, nearly twice as much. Chlorine gas is less favorable as an oxidant, yielding only 6.5 kcal per mole of methane consumed.

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