TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The hot water produced by the solar heat collector can radiate heat to inner part of the marsh gas generator through the radiating tube to make the temperature in the marsh gas generator reach and always keep at constant temperature of 54 degrees C. A certain amount of fermenting raw material is fed in the marsh gas generator from the feeding hole each day. When the gas pressure meter displays that the marsh gas produced in the marsh gas generator is 1500 Pascal, gas can be pumped by a vacuum pump externally connected. The first pressure sensor and the second pressure sensor are respectively installed at the places where the storage amounts of marsh gas generator are 83.3% and 85.9%. When the marsh liquid reaches the height of 85.9%, the first sensor at the positions sends out signal and the slurry pump at bottom of the marsh gas generator begins to rotate to discharge marsh residue, while the marsh residue is continuously discharged, liquid level of marsh liquid in the marsh gas generator gradually reduces when the liquid level reduces to the height of 83.3%. The second sensor at the position sends out signal and the slurry pump stops working. The device makes the quality and volume of material liquid in the marsh gas generator basically stable so that the marsh gas generator can stably produce gas. The pond wall of the marsh gas pond can be made by making foaming mold of inner and outer walls according to the shape of marsh gas generator that is made beforehand, making outer wall by the foaming mold according to shape thereby making the inner wall by the mold according to the shape of pond wall added with radiating tube, before foaming. Fixing the inner and the outer mold beforehand, then installing the radiating tube in the inner wall and fixing, finally pouring polyurethane from the casting mold for foaming, after ending foaming, taking out inner and outer molds, finishing making main part of the marsh gas generator.