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Cons of Gasifiers


The use of biomass gasification for power production is not new, but its use has been so far been limited and its contribution to the overall power production has so far been negligible in India. The producer gas derived from biomass gasification can be used for either producing power (by use in a gas engine) or can be used for thermal applications.

With better technologies evolving for both gasifiers and gas engines, it can be expected that biomass gasification could start contributing a lot more to the overall power production in India. For starters, biomass gasifiers are reactors that heat biomass in a low-oxygen environment to produce a fuel gas called the producer gas. The gas produced from a gasifier can drive highly efficient devices such as gensets, turbines and fuel cells to generate electricity.

A biomass gasification system consists primarily of a reactor or container into which fuel is fed along with a limited (less than stoichiometric, that required for complete combustion) supply of air. Heat for gasification is generated through partial combustion of the feed material. The resulting chemical breakdown of the fuel and internal reactions result in a combustible gas usually called producer gas.

Though gasifiers are really special in their own way, they have their limitations. Gasification is a complex and sensitive process. There exists high level of disagreement about gasification among engineers, researchers, and manufacturers. Several manufacturers claim that their unit can be operated on all kinds of biomass. But it is a questionable fact as physical and chemical properties varies fuel to fuel.

Gasifiers require atleast half an hour or more to start the process. Raw material is bulky and frequent refuelling is often required for continuous running of the system. Handling residues such as ash, tarry condensates is time consuming and dirty work. Driving with producer gas fueled vehicles requires much more and frequent attention than gasoline or diesel fueled vehlicles.

Getting the producer gas is not difficult, but obtaining in the proper state is the challenging task. The physical and chemical properties of producer gas such as energy content, gas composition and impurities vary time to time. All the gasifiers have fairly strict requirements for fuel size, moisture and ash content. Inadequate fuel preparation is an important cause of technical problems with gasifiers.

Gasifier is too often thought of as simple device that can generate a combustible gas from any biomass fuel. A hundred years of research has clearly shown that key to successful gasification is gasifier specifically designed for a particular type of fuel. Hence, biomass gasification technology requires hard work and tolerance.

As I said, gasifiers are indeed special in their own way. I’d rather we just wait for the technology to advance in the future to go far beyond its limitations. After all, as I said then and I will again, petroleum is not here forever, and we need more sustainable feedstock and advanced technologies for processing.

 

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Narasimhan Santhanam

Thank you for reading this post – hope it was helpful. You can connect with me at narsi@solarmango.com . My detailed profile here and my LinkedIn profile here

Posted in: Biomass Power

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