Different fuel type's energy density, availability and ecological footprint?

Question

What are petrol, diesel, electric and steam's energy density, availability and ecological footprint? And what are advantages/disadvantages of them?

Answer 1

How about biodiesel or recycled vegetable oil?

Use vegetable oil recycled from this fast food world to power your diesel vehicle.

Emissions report for diesel vs biodiesel vs vegetable grease

http://www.greasecar.com/tech.cfm

Find out more:

http://www.biodiesel.org/resources/biodi...

Answer 2

Well, take electric and steam out of the discussion as energy sources.  They are not sources so we can not describe energy density. We could include batteries or super flywheels to act as a carrier for electricity and these have an energy density, as in kWh / kg.  Likewise we could include within steam's sources coal or bunker oil. But not the steam generated from it.

Diesel and steam from oil are fairly close in terms of energy density per kg of fuel.  They are both about 20% more energy dense than gasoline.

We can use CNG and propane in much the same ways to be burned in an internal combustion or steam power. Each gives energy density comparable to gasoline, but requires A heavy shell, cutting into effective energy density.