Energy Content by Weight

Sources:

1) Energies, An Illustrated Guide to the Biosphere and Civilization by Vaclav Smil (MIT Press, 1999).
2) Energy and Problems of a Technical Society J. J. Kraushaar and R. A. Ristinen (John Wiley and Sons, 1993).

Fuel                                                     MJ/kg

Hydrogen                                         114.0
Gasoline                                           46.0-47.0
Crude Oil                                         42.0-44.0
Pure Plant Oil                                  38.0-37.0
Ethanol                                             29.6
Best bituminous Coal                      27.0-29.0
Common Coal                                 22.0-20.0
Cereal Grains                                  15.2-15.4
Air-Dried Wood                             14.0-15.0
Lean Meat                                        5.0-10.0
Potatoes                                            3.2-4.8
Carbon Fiber Flywheel                    0.77
Lithium Batteries (at 400C)            0.36
Steel Flywheel                                 0.17
Lead Batteries                                  0.07-0.14


Questions:

1) Why is it so difficult to build an electric car with a reasonable cruising range?

2) Why are automobile companies so interested in hydrogen as a fuel? What difficulties are there with using hydrogen as a fuel?

3) Plant oil has a high energy content (and wood and grain are much higher than batteries). Why isn't the automobile industry pursuing the use of these oils (or wood or cereal) for cars? (Hint: Find out how much energy it takes to produce a kg of plant oil.)

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