earth tube cooling
I subscribe to a permaculture forum, and just read an anecdotal story about a man who dug a trench and put in several barrels with the ends cut out. He welded them together, covered the tube with 2 feet of dirt and put a swamp cooler on one end, connected to his house ducts. He runs the cooler without water, but with the pads (to keep critters out) and reports that his rooms are much cooler.
I thought it was a story worth sharing.