Gasification is a process that uses heat, pressure, and steam to convert biomass directly into a gas comprising primarily of carbon monoxide (CO) and hydrogen (H2). Gasification is a thermochemical process unlike an incineration or combustion process. Gasification is a conversion process intended to produce more valuable and useful products from carbon containing materials. Gasification processes operate with limited amounts of oxygen, while combustion processes operate with excess oxygen. Combustion or incineration thermally destroys carbon into heat, while gasification converts carbon into valuable environmentally friendly intermediate products. Gasification can use natural gas, coal, oil, biomass and just about any carbon containing material as a feedstock. In our commercial operations, R3 Sciences is working primarily with gasification using natural gas and biomass as feedstocks.
Any wood type biomass is a renewable resource. In general, biomass refers to wood, woody products, grasses, crop residue, construction & demolition (C&D) waste, and post consumer recycled paper products. The class of biomass is generally selected by regional availability. Gasification reactors may vary in design by the level of oxygen used in the reactor. Gasifiers may use atmospheric air which contains approximately 18% oxygen, or use additional equipment to use an enriched oxygen feed which minimizes the overall volume of gas and reduces the levels of nitrogen in the tail gas. A reduction in nitrogen corresponds with an increase in the BTU value of the syngas produced by the gasifier.
In the case of biomass, the feedstock is prepared by reducing its size and shape to a level required for feed inlet. (e.g. branches, logs, etc. are usually chipped). The moisture content is normally reduced to around 25% on a mass basis. All commercial gasifiers require energy source to start. This initial energy can come from a simple gas or oil burner, or even and electric source. Once the gasifier is operational, no additional external fuel is required.
During operation, the gasifier produces a synthesis (Syngas) gas. Syngas can be used directly as a fuel to power a reciprocating engine or turbine, or fire a boiler to produce steam or electricity. When mixed in air, syngas can be used in gasoline or diesel engines with only a few modifications to the engine. Gasification has proven successful when used in conjunction with gas engines and gas turbines to obtain a higher conversion efficiency than conventional fossil-fuel electric power generation. Gasification can help meet renewable energy targets, address concerns about global warming, and contribute to meeting global environmental targets. The syngas product from gasifiers are exposed to cleanup resulting in a much lower presence of harmful emission elements.
The by-products of combustion is an ash material. On the other hand, the by-product of gasification is a charcoal. Charcoal consists of unreacted carbon and mineral matter present in the gasifier feed. The remaining charcoal has a market value as a fuel or as a source to produce an activated charcoal for water filtration.