NOVELTY - Biogas generator comprises either: a reservoir (22), an inflow conduit, a gas outflow conduit, a heat exchanger, a first pump, a second pump, and a solar power and heating system (50) comprising at least one solar cell and a solar panel; or a reservoir, a lid shaped to mate with the top of the reservoir, and a rigid annular support fixedly attached to the interior of the reservoir.    USE - The biogas generator is useful for: converting liquefied organic material to gas and slurry via an aerobic digestion process (claimed); and producing biogas (methane) and a slurry from waste materials including biological or organic waste, animal feces and urine, where the biogas and slurry are useful to heat buildings and fertilize the fields.    ADVANTAGE - The biogas generator has solar power system, hence does not require external power source to operate.    DETAILED DESCRIPTION - Biogas generator comprises either: a reservoir (22) to hold the liquefied organic material, an inflow conduit through which the liquefied organic material is pumped into the reservoir, a gas outflow conduit through which the gas exits out of the reservoir, a heat exchanger positioned inside the reservoir to heat the liquefied organic material in the reservoir, a first pump connected to pump the liquefied organic material through the inflow conduit into the reservoir, a second pump connected to pump a fluid through a closed loop conduit and through the heat exchanger, and a solar power and heating system (50) comprising at least one solar cell and a solar panel through which a part of the closed-loop conduit passes the solar cells converting solar energy striking the solar cells into electricity used to provide power to the first and second pumps and the solar energy striking the solar panel heating the fluid traveling through the part of the closed-loop conduit, where the heated fluid heats the liquefied organic material as the heated fluid is pumped through the heat exchanger to facilitate the anaerobic digestion process; or the reservoir, a lid shaped to mate with the top of the reservoir and comprising many wheels and at least one agitators fixedly attached to an underside of the lid, and a rigid annular support fixedly attached to the interior of the reservoir to support the lid and comprising a flat surface on which many wheels rests when the lid is placed on the reservoir. The lid is rotatable on many wheels so as to cause at least one agitator to move through the liquefied organic material in the reservoir to agitate the liquefied organic material. An INDEPENDENT CLAIM is also included for a method of converting liquefied organic material to gas and slurry via an anaerobic digestion process, comprising: pumping the liquefied organic material into a reservoir through an inflow conduit using a first pump; pumping a fluid through a closed-loop conduit passing through a heat exchanger positioned inside the reservoir using a second pump; converting solar energy striking at least one solar cell into electricity used to provide power to the first and second pumps; and heating the fluid traveling through the closed-loop conduit by solar energy striking a solar panel through which the closed-loop conduit passes, where the fluid heats the liquefied organic material as the fluid is pumped through the heat exchanger to facilitate the anaerobic digestion process to convert the liquefied organic material to the gas and the slurry.    DESCRIPTION OF DRAWING(S) - The figure shows components of the closed system biogas generator.    Biogas generator system (10)    Sealed tank (20)    Reservoir (22)    Lid (26)    Solar power and heating system (50)