NOVELTY - The method involves establishing target production rate and target energy content for synthesizing gas output from a gasifier. Two feed materials are provided as a mixture to the gasifier. The gas produced by the gasifier is monitored. A feed rate of the mixture is adjusted to maintain target production rate based on data obtained by monitoring the gas. A feed rate of the feed materials is adjusted to maintain the target energy content. The data is analyzed to identify levels of carbon monoxide, hydrogen and total hydrocarbons in the gas.    USE - Method for producing synthesis gas by mixing two different potential feed materials e.g. construction and demolition waste, municipal solid waste, rubber, refuse derived fuel, wastewater sludge, plastic waste, medical waste, waste oil and scrap tires (all claimed), with different target energy contents (BTU) formed as composite feed stream to be fed into a gasifier. Can also be used for non-waste materials such as coal or petroleum coke.    ADVANTAGE - The method enables realizing designing and dimensions of reactor's volume to be above a metal bath to maximize synthesis gas production efficiency and to reduce particulate load in the gas stream. The method enables utilizing molten bath and vitreous material layers that are acting as effective particulate filters, and providing oxygen injection ports that are located above the bath to direct oxygen flow in an upper portion of the reactor in order to supply sufficient amounts of oxidizer to convert carbon dust into carbon monoxide. The method enables preventing particulates, which are exiting in the reactor by keeping gas-exiting velocity to be lower than dust-settling velocity by adding expansion chambers in an exhaust section of the reactor and by installing a cyclone on an exit from the reactor.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a computer-implemented method for controlling synthesis gas production.    DESCRIPTION OF DRAWING(S) - The drawing shows a flow diagram illustrating a process for a waste stream.