Energy, Fuels & Bombs

Filling the tank with unleaded has become such a mundane act that few of us spare a thought for the mind-boggling amount of energy being transferred.

Kerosene and oxygen destroyed Russia's giant Kursk submarineA modern military torpedo, for example, is powered by kerosene, a common hydrocarbon blend, and oxygen. The energy required for it to hunt down a ship and deliver the warhead – the hydrodynamic equivalent of a cheetah running down a gazelle – is far greater than the amount of energy in the high-explosive tip. And that basically explains why a simple malfunction in the fuel system of a torpedo was sufficient to sink the gigantic Russian submarine The Kursk in August 2000. Around 700 litres of kerosene came into contact with the liquid that supplied the oxygen for combustion (a concentrated form of hydrogen peroxide). The energy released blew the front end off a 23,000-tonne machine twice as long as a Boeing 747, built to withstand hundreds of feet of water pressure. The explosion measured 1.5 on the Richter Scale.

Next time you pump 50 litres of petrol into your car, consider this: A Holden Commodore travelling at 110km/h possesses around 800kJ (kilojoules) of kinetic energy. If that energy is explosively transformed into the car’s structure, say by running head-on into an unyielding, massive object, the impact will be unimaginable. The vehicle and its contents will be rendered unrecognisable. Eight hundred kilojoules is a vast amount of energy.

Twenty-five millilitres of petrol is a ridiculously small volume. A child could hold it in two cupped hands (although the World Health Organisation recommends refraining from skin contact). Those cupped hands would be holding and amount of petrol equivalent to 800kJ of potential combustion energy, the same as the kinetic energy of the Commodore at the legal freeway limit above. (It’s definitely a good reason not to smoke while refuelling, and to earth jerry cans before introducing the refuelling nozzle.) A full tank of 50 litres contains the same amount of energy as 2000 Holden Commodores all travelling at 110km/h.

Petrol is such an amazingly good fuel that the energy locked inside it beggars belief.

fuelJohn CadoganComment