Biomass gasification is identified as a viable technology to tap the source of renewable energy and reduce GHG emission.

Past Experience and Problems

Many biomass gasifiers were manufactured during World War II to help solving petroleum shortage problem. These were mostly downshaft gasifiers for cars using charcoal as fuel.

The limitations of fuel and capacity coupled with tar indused high maintenance imposed significant disadvantages to biomass gasifiers. This lead to the rapaid decline of the industry among other reasons such as cheap petroleum price and reliable petroleum engines after the war.

In recent years, the lack of environmental protection measures in many gasifier operations that caused severe secondary pollution also lead to the hesitation of potential users.

Biomass Gasification

Most of us believe wood (a kind of biomass) burns. However, a close look at the fireplace reveals that wood does not burn at the wood surface. The pyrolysing wood evolves a combustible gas that burns whenever it encounters oxygen in the air.

In simple term, Biomass Gasification is the breaking down of biomass material under intense heat in the absence of oxygen to produce volatile vapor as a kind of combustible gas.

The volatile vapor, usually known as Producer Gas, contains H₂, CH₄, CO as the sources of energy and typically CO₂ and N₂ as the unwanted diluents.

Why Gasification

One may say direct burning of biomass in boilers to produce steam for turbine is a proven technology. However, this operates at a relatively low efficiency and requires large steam plant and huge initial investment to justify the economy of scale.

Moreover, combustion produces air pollution unless stringent exhaust treatment is adopted at a relatively high cost. Ash fouling in boilers is also a common problem with biomass materials that involves extensive maintenance and down time.

Gasification of biomass on the other hand produces fuel gas that feeds gas engines to generate electricity at higher efficiency but lower initial investment and with cleaner exhaust.

The economic radius of biomass collection governs the power generation capacity and initial capital cost due to the inherent low energy density of biomasses. A large biomass boiler power plant will suffer additional transportation costs for a very large collection area.

Biomass Gasification Engine System (BGES) on the other hand has the flexibility to suit local economic haulage radius for standalone power plant. De-centralized BGESs become an economically and technically favored option.