[lifeformed]

Hmm... maybe there are more common sources of strong-but-slow power. The heat expansion of bridges? The weight of vehicles sitting idly at a stoplight? The swaying of skyscrapers?

I wonder if you could make a purely mechanical solar panel that way. Get a giant sheet of metal, put it out in the sun, and attach this gear arrangement to it, braced by opposite sides of the expansion. Hmm... I kinda want to make this now.

[ultimoo]

I think the heat expansion of bridges can be put to use to power an interesting gear system art installation at best :-)

[lifeformed]

Still worth it! I'm gonna try building that mechanical solar panel.

[bmelton]

What you're describing is a move up the Kardashev scale[1]. The Kardashev scale measures how tech-savvy a society is by how they collect and use energy. A Type I society on the scale is able to harness and store all the energy generated on the planet, which we're moving towards now. Regenerative braking and such are definitely progressions in that area, but presumably bigger gains could be had by harnessing the power of tectonic plate movement, volcanic activity, wind, solar, etc.

[1] - http://en.wikipedia.org/wiki/Kardashev_scale

[lifeformed]

I wonder if we'll be able to harvest all ambient sound one day.