NOVELTY - The biomass generator has a hot air furnace producing hot air circulating in a closed circuit around a combustion chamber. An air heat exchanger (24) heats the organic liquid (27), circulating in a liquid closed circuit, into pressurized gas (30) using the heat from hot air. The pressurized gas is used for moving a piston in an expansion engine (40). The generator also has an oil recuperator to recover oil. The expansion engine has an expansion chamber having insulating material of ceramics, stainless steel or polytetrafluoroethylene.    USE - Biomass generator for biomass gasification power generator system (claimed), particularly for producing electricity e.g. for powering electrical appliances, lighting and building communications.    ADVANTAGE - The biomass generator burns biomass, such as wood logs, wood chips, or agricultural biomass, obtained from forestry industry, without having to transform biomass into different matter, and without using another system e.g. pyrolysis, to create electricity. Since the piston is not fixed to a rod, the spring makes it possible to avoid cavitation. The intake valve reduces force needed for the spring to close the valve so as to reduce friction or wear of components and reduce loss of mechanical energy. The intake valve uses an immovable piston and interchangeable seal to reduce maintenance expenses. The intake and exhaust valves open at same time to permit lower pressure gas to circulate in the expansion engine to heat mechanical components and prevent inappropriate amount of gas condensation in the engine. The oil recuperator enables recovery of oil leaking from the motor.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a biomass gasification power generator system; and    (2) a method for generating heat and energy from biomass.    DESCRIPTION OF DRAWING(S) - The drawing shows the schematic view of a lubricating oil cycle.    Air heat exchanger (24)    Organic liquid (27)    Pressurized gas (30)    Expansion engine (40)    Level sensor (LS)