Described are methods and systems for producing synthesis gas. In some embodiments, the method includes microbiologically converting biological material to form methane and CO2; and reacting methane and CO2 formed in (a) with water and metal to form synthesis gas. Optionally, the method also includes cutting vegetation; fermenting the vegetation to form biogas comprising methane and CO2; and reacting the biogas with water and metal to form synthesis gas and metal oxide. In some embodiments of the invention, reacted metal is regenerated from metal oxide produced in the reaction. In some embodiments the regeneration comprises reacting the oxide in a bath of boiling zinc.