In the last few years, biomass (If you are asking: What the heck is biomass? See here) based power generation has been seeing an increase the world over, as such generation is a carbon-neutral method of generating power.
The two prominent mechanisms for generating power from biomass are:
- Combustion – By burning the biomass in a furnace/boiler and using the heat to generate steam and run a turbine. This route is commonly known as biomass combustion, and is usually the route used by medium and large biomass power plants (5 MW and above, typically)
- Gasification – When used at a suitable temperature (about 700-800 deg C) and in a limited supply of air, the biomass, instead of burning completely, gets converted into a organic gas called producer gas (some also call it syngas, but syngas technically refers to a somewhat different mixture of organic gases). The producer gas can be used in a gas engine for power generation. This route is known as biomass gasification. Gasification based power generation can be done even at small scales (10 kW and above), and this makes gasification a preferred route for power generation in remote rural areas with limited or no grid but where biomass availability is high.
- The above two are the most prominent avenues from which power generation using biomass is achieved. Where the biomass refers to wet organic waste such as human and animal waste, kitchen waste and food waste, the most prominent method used to generate power is Biomethanation or Anaerobic Digestion – in which select bacteria act on the waste and generate biogas. When such biogas is generated in medium or large quantities (for instance at sewage treatment plants), the gas can be used in gas engines to generate power. Very small scale generation of biogas at a household or a small community level might not be suitable enough to run power plants; instead, the gas can be better used for local heating applications.
Having been involved in research for both combustion-based and gasification-based power generation, I can say that these two in fact provide different benefits. Combustion-based power generation provides renewable power on scale; typically, the power is fed to the grid just as any other thermal power station does. Gasification based power generation is a more distributed form of power generation, especially as it can operate on smaller scales. The key benefit this could provide is as a source of power for rural and remote regions that suffer from significant energy insecurity.
Biomethanation-based power generation, in my opinion, is more a solution for waste disposal than a serious avenue to generate large scale power. In fact, for most countries, the potential from biogas based power generation will be at least an order of magnitude lower than that for biomass based power generation.