TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: In the system (I): each of the wheel segments extend radially from the center axis; the cylindrical body is closed at both ends by first and second cover; the gas conduit includes a valve assembly actuated by agricultural waste within the digester capable of blocking the flow of gas out of the digester assembly; and the power generation device is an electricity generating motor. The system (I) further comprises: a heat exchanger connected to the motor and the water vessel to use the heat from the electricity generating motor to heat the water of the water vessel; a solar energy collection device connected to the water vessel to heat the water contained in the water vessel with collected solar energy; a valve activated by a level of agricultural waste within the digester assembly to restrict biogas produced by the digester assembly from flowing into the gas conduit such that a desired agricultural waste level in the digester assembly is maintained, where the digester assembly utilizes the force of biogas produced within the cylindrical body to transport digested agricultural waste out of the hollow interior of the cylindrical body; and conduits extending out of the interior of the cylindrical body such that biogas pressure within the interior of the cylindrical body facilitates the expulsion of agricultural waste out of the interior of the digester assembly through the conduits. In the system (II), each of the wheel segments has many perforations at the outer edge adjacent to an attachment point between each wheel segment and the hollow cylindrical body, where the wheel segments have a concave surface on one side and a convex surface on an opposite side, the concave and convex surfaces of the wheel segments are uniformly oriented such that each concave surface of each wheel segment faces a convex surface of an adjacent successive wheel segment, and the arcuate, contoured surface area of the wheel segments trap rising biogas under the concave surfaces of the wheel segments on one side of the digester assembly such that an ascending force of the trapped biogas under the concave surfaces rotates the cylindrical body. Preferred Method: The method of generating biogas from agricultural waste further comprises: providing a heat exchanger connected to the power generation device and the water vessel, where the heat exchanger heats the water of the vessel from the heat given off by the operation of the power generation device; providing the wheel segments with an arcuate, contoured surface area that restricts biogas movement within the digester assembly to produce induced agitation of agricultural waste; providing a valve activated by a level of agricultural waste, where when the level of agricultural waste reaches a predefined level within the digester assembly, the valve restricts biogas produced by the digester assembly from flowing into the gas conduit such that a desired agricultural waste level in the digester assembly is maintained. In the method of generating biogas from agricultural waste, when the valve restricts biogas produced by the digester assembly from flowing into the gas conduit, the digester assembly utilizes the force of biogas produced within the cylindrical body to transport digested agricultural waste out of the hollow interior of the cylindrical body.