I just came across the “Dream Farm” concept through a link at Energy Bulletin, and am fascinated by what I’ve read in this article at the UK’s Institute for Science in Society web site (pdf version with diagrams here). I won’t claim to completely understand it all, as the article’s fairly complex and contains lots of facts and figures along with healthy doses of theorizing. Essentially, though, it boils down to a self-contained, zero-emission, zero-waste farm. The basic overview:
[An] anaerobic digester takes in livestock manure plus wastewater and generates biogas, which provides all the energy needs for heating, cooking and electricity. The partially cleansed wastewater goes into the algal basin where the algae produce by photosynthesis all the oxygen needed to detoxify the water, making it safe for the fish. The algae are harvested to feed chickens, ducks, geese and other livestock. The fishpond supports a compatible mixture of 5-6 fish species. Water from the fishpond is used to “fertigate” crops growing in the fields or on the raised dykes. Aquaculture of rice, fruits and vegetables can be done in floats on the surface of the fishpond. Water from the fishpond can also be pumped into greenhouses to support aquaculture of fruits and vegetables. The anaerobic digester yields a residue rich in nutrients that is an excellent fertiliser for crops. It could also be mixed with algae and crop residues for culturing mushrooms after steam sterilisation. The residue from mushroom culture can be fed to livestock or composted. Crop residues are fed back to livestock. Crop and food residues are used to grow earthworms to feed fish and fowl. Compost and worm castings go to condition the soil. Livestock manure goes back into the anaerobic digester, thus closing the grand cycle. The result is a highly productive farm that’s more than self-sufficient in food and energy.
The concept was originally created by Professor George Chan, who apparently created “dozens” of such farms in the underdeveloped world. The article deals with a second generation of Chan’s idea which, unfortunately, is having trouble finding funders. The ISS article on Chan’s original “Dream Farm” is under lock and key in the members’ section, but if anyone can provide more information, please, speak up!