Only a couple of %, but it is growing. The basic problem is that the western consumer is using ludicrous amounts of energy per head. There is no way we can support that level of consumption with renewable resources. Certainly not if more and more people of developping nations are added.

That is just not sustainable no matter how you slice it and that is why our societies are going to change. Irrespectibally whether Nuclear energy, shale oil, coal or whatever is used.

Basically, we only need to look at what a family car burns off. A person on a bicycle uses about 250 watt to get somewhere at 15 miles per hour. 37000 Joules per kilometer (60000 per mile). When I use my car, a very fuel efficient Toyota starlet (15 km to the litre = 60 mpg) I'm burning off 2400000 joules per km or 65 times as much energy. Take your average redneck 8 cylinder 6 liter pick-up truck and be really amazed. Or take air travel !

What if we fitted out these bicycles with small motors and drive around like that ? Take a wild guess at the energy (and money) saved by that. Things like that will happen as that is the only way to get the job done. Looking for other sources to sustain our current consumption level are simply beyond imagination.

Wouter