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"Taxiing to the runway consumed 2 tons of fuel."

This always bothered me - how come it's easier/cheaper to burn 2 tonnes of fuel, than just tow the damn thing to the runway?

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2 tons of fuel cost around $2000 (obviously this would vary, but that's the sense of it), a single seat on the Concorde cost $6000+ one-way towards the end of its service. Apparently the economics of a) retrofitting an auxiliary power unit to the Concorde so that it could be towed with engines off and b) adding personnel to the ground crew for towing the airplane did not make sense. And even if the airline cared greatly about the environmental impact, 2 tons for a few Concorde flights is a tiny fraction of even a single airline's fuel usage.

The concord didn't have an auxiliary power unit to provide energy with the engine off. So it needs to rely on energy from the gate or a special external unit. This unit was also necessary to provide the energy to start the engine.

Obviously, it could start the engine but don't use them for taxiing, except that the 4 engines were so powerful that at idle produced enough thrust to move the plane (and they were burning a lot of gas). So better to taxi on it's on power than been towed.

P.s: the 2 tons figure was the higher estimation, not the regular consumption...

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