Biologists say that humans are currently using 40% of the Net Primary Productivity of the planet.  That ratio  is not sustainable, and has to be--will be--reduced in the future.

While the 40 % figure is undoubtedly true, the primary photosynthesis uses only about 2 % of the incident solar energy (and that is only over land - over ocean, the number is considerably lower). The rest is either reflected or goes straight to (mostly) unrecoverable heat (only mostly so, because it is this heat that drives the climate system - i.e. the wind and ocean currents that we can exploit for energy).

In this sense, the only difference between solar and wind is that solar taps into the greater reserve of free energy - ultimately, both wind and solar exploit the remaining 98 % of incident solar radiation. The chopping down of trees to accommodate wind farms or solar panels is thus more an issue of limited space (and the current low conversion efficiency) than limited free energy.

There are limits to the scale of any energy capture technology that we can safely deploy without changing weather patterns (irrespective of whether we are talking wind or solar), but at the moment the relatively modest conversion efficiency of the technology in question makes that a moot point.

- Jake

Friends come and go. Enemies accumulate.