if you find that you can't afford the installation of personal reuseable energies, then you could just change to a company who guarentees that all their energy is from renewable sources. This is what I have just done.
Try searching for "the good energy company" and see if you can switch. It is not particularly cheaper, it was in fact no different than sweb, but I would rather pay a reuseable company than not.
I found them after reading a really good book by friends of the earth called: "save cash and the planet." It was full of excellent ideas for both....