The Patch- Whitley digester is at left and their collector tank is on the right of the first photo. The smaller tank in the center contains a submarine compressor. The compressor weighs approximately 2,000 pounds, runs at 550 rpm and produces 20 cubic feet of 3,000 psi output per minute. Surplus it cost the Patch- Whitley team $1,000 . . . and it takes 55 horsepower to run the half-brass monster. Bill and Dale store some of their methane in 15 surplus submarine air tanks. Each one cost $150 and will hold 15.5 cubic feet of gas at a pressure of 3,000 psi. The system has cost Patch-Whitley a total of $4,000.