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 i

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.