And the profits grow

[eppie]

The reason photosynthesis isn't efficient is because 90% of the energy being stored is in turn used to maintain the survivability of the organism doing the storing. Non biological photosynthesis, as technologies advance, will circumvent this limitation. The "huge breakthroughs" you speak of still assumes a linear technology advancement path when technologies advance on exponential curves (or more accurately multiple exponential curves). The question isn't "even if we can increase the efficiency *this much*" it's a question of how accurately we can predict where we are on the technology curve for solar power (or hydrogen fuel cells, etc. etc. etc.). The efficiency is going to get better, I'm confident in making that prediction. Thinking about technology in a linear fashion tends to lead to two falacies: we overestimate tech advancements in the short term, and we vastly underestimate tech advances in the long term.

Good example is the transistor size (and PC memory). There is a road map and for 20 years this is followed even though there were and are many obstacles. I share your ideas on the future of solar. Harvesting 20 % of all the light on a certain area is anyway a big number. Organic solar cells have been made in labs going up to 13 % energy conversion. Once we have cheap reliable organic cells we can put them every where (cars, houses, windows) without bothering us..... this should give us a considerable part of our energy needs.