Don't forget the Dyson Sphere concept
Admittedly it would involve just a little more engineering and construction work (we'd need to take apart Jupiter and maybe one or two other planets for building materials), but in the end we would be able to capture 99% of the energy put out by Sol, which we will need if our civilization continues to grow.
The details here:
http://www.nada.kth.se/~asa/dysonFAQ.html
http://www.aeiveos.com/~bradbury/MatrioshkaBrains/index.html
http://www.aleph.se/Trans/Tech/Megascale/dyson_page.html
http://users.rcn.com/jasp.javanet/dyson/
Of course there are always Ringworlds, and then we'll have to work on a galactic Dyson Sphere....