I was looking into how to grow plants in the winter. This link has an e-book which shows you how to build a small biodome or indoor greenhouse for like 200 dollars. And then it uses the heat from the ground by you digging a hole and blowing a little fan through to heat the biodome to keep the temperature in the biodome steady throughout the winter. . I thought it was very cool and that I would share. Click Here to check out the videos and get the how to ebook!