It is very hard to find anything to match petroleum in the energy density stakes.
As Rob Hopkins says in the TED Talk introductory video on our front page:
[color=#4040BF][i].. litre of oil distilled over 100 million years of geological time ‘ancient sunlight’ contains the energy equivalent of about five weeks of hard human manual labour…[/i][/color]
For a hands-on experience try cooking on an alcohol fueled stove compared with a hydrocarbon (kero petrol LPG etc) fueled one. No comparison.
It’s no wonder we strive so hard to keep sucking the stuff out of the ground.