Biomass Gasification - A Review

Biomass gasification process, biomass converts organic or fossil based carbonaceous materials into a gaseous mixture of CO, CO2, CH4, H2 and H2O. This is achieved by reacting the material at high temperatures (>700 °C), without combustion, with a controlled amount of oxygen and/or steam. In gasification the combustion is carried at sub-stoichiometric conditions with air-to-fuel ratio being 1.5:1 to 1.8:1. The resulting gas mixture is called syngas (from synthesis gas or synthetic gas) or producer gas. It offers the most attractive alternative energy system for agricultural purposes. Most preferred fuels for gasification have been charcoal and wood. However biomass residues are the most appropriate fuels for on-farm systems and offer the greatest challenge to researchers and gasification system manufacturers. The power derived from gasification of biomass and combustion of the resultant gas is considered to be a source of renewable energy. Maximum usage of producer gas has been in driving internal combustion engine, both for agricultural as well as for automotive uses. However direct heat applications like grain drying etc. are very attractive for agricultural systems. A spark ignition engine running on producer gas on an average produces 0.55-0.75 kWh of energy from 1 kg of biomass. Biggest challenge in gasification systems lies in developing reliable and economically cheap systems. Future development should concentrate on reducing the cost of the gasification plant itself since it is the gasification plant the main cost factor. Also future applications like methanol production, using producer gas in fuel cell and small scale irrigation systems for developing countries offer the greatest potentialities.