Biomass is solar energy stored in organic matter. It is carbon-based and composed of a mixture of organic molecules such as hydrogen and oxygen. Biomass energy can only be sustainably harvested when it does not upset the fragile balance of ecosystems. SEN opposes the logging of native forests for bioenergy due to its unsustainable nature and that it creates a market demand to consume more.
Sustainable biomass is the conversion of waste biomass to energy. Sustainable biomass resources include:
- Agricultural waste, such as bagasse from sugarcane and waste wood from plantation timber mills.
- Household waste that would otherwise go to landfill.
- Oil Mallee trees, which can also improve the soil conditions of marginal land by combatting dryland salinity and soil erosion, enriching soils and sequestering carbon.
- Algae, which can grow on salty lakes.
- Sewerage plants.
Biomass can be converted into energy through a range of technologies.
Direct combustion is still the most common technology in Australia. In this method, biomass is burnt to heat water, which in turn generates steam for running a conventional generator.
Gasification is a more advanced technology, where the biomass is combusted in high temperatures with very little oxygen and the complex molecules separate into a cleaner, hydrogen-rich gas, which can be used in a fuel cell or gas turbine.
Biological treatments are used extensively for wet organic matter such as pig manure and sewerage. One such treatment, anaerobic digestion, involves the use of methanogenic bacteria to break up organics and produce methane.
It is estimated that the technologically sustainable energy potential of biomass is greater than the world's current electrical generating capacity.
1. Kreith, F. & Goswami, D. Handbook of Energy Efficiency and Renewable Energy. CRC Press, 2007.
You can view the excellent presentation "Biomass Pyrolysis for energy, fuels and char in the WA Wheat Belt" by Ben Rose here.
View useful links related to biomass energy.