Muros writes "I've had an idea floating around in my head for years; using the Sahara desert. I have put some thought into possibilities, without ever actually trying to figure out the actual viability. What I envision in my dreamings, is renting most of the Sahara from the the respective governments, under a 50 or 100 year lease, under a government similar to the distributed republics of sci-fi authors, controlled by the UN or African Union. Then, (in an environmentally friendly way in as much as possible) cover most of the Sahara with an enormous hermeticaly sealed greenhouse made of solar panels. The main issue would then be the provision of water (hence the sealing) which could be provided by desalination plants at Africa's coast and pumped into the desert (this would become less of an issue as time goes by, with water recycling), power coming from the solar panels. The costs of setting up such a venture would be astronomical, but in the long run it could provide a huge amount of both horticultural produce and electricity, and it would provide a much needed income stream to what is possibly the most resource rich, but still economically the poorest, continent in the world. It would also provide huge amounts of employment in the construction. Ok, you can start laughing now."