The producer gas from the gasification process contains the energy that was contained in the original biomass material. The efficiency of the conversion of this energy from the original biomass into the producer gas is above 90%. Depending on the age and state of the boiler, when biomass is burned directly in a biomass fired boiler much of the energy produced from the combustion of the biomass (20% to 60%) escapes out the stack. The steam produced by such a boiler will therefore only contain 40% to 80% of the energy in the biomass. The gasification process is typically 50% more efficient at converting the energy contained in the biomass into a useful form. This increased efficiency is due in a large part to the closed process design, where only a small amount of the process heat escapes.
Producer gas can be readily used to drive both reciprocating and gas turbine engines. Since the producer gas will combust and expand within these engines, it gives a more efficient conversion to mechanical energy than the use of steam turbines where the steam is injected at high temperature and pressure. Also, the producer gas can be introduced into the engine at reasonable temperatures and pressures, avoiding safety design requirements that are needed with high pressure steam. With the increased efficiency of a gas turbine over a steam turbine, the energy converted from the biomass through gasification and the use of a gas turbine engine can increase overall efficiency by 100% over a biomass fired boiler and steam turbine. Therefore, gasification derived producer gas is both a more convenient form for the biomass energy as well as a more efficient use of the energy than direct firing of the biomass
As biomass is heated for combustion or gasification, many hydrocarbons are produced as the material pyrolyzes and breaks down. These hydrocarbons become tars and particulates. In open burning, the tars and particulates are carried into the environment through the stack. Since many of them are considered pollutants, they must be scrubbed out of any emissions from the combustion process. This is typically done by maintaining high stack temperatures to further break down and destroy the tars and then scrubbing out what is left. These approaches reduce efficiency and add cost to the process. Since gasification is a closed process, these pollutants are broken down within the process and then whatever is left is filtered out of the gas. No efficiency is lost and the gas filtering is done in a closed system. There is no stack or any significant emissions from the gasification process.