Power from biomass
The biomass used as an energy source is usually waste plant and animal matter. The energy value of biomass from plant matter originally comes from the sun through the process of photosynthesis. Biomass can be used in two main ways to produce electricity.
Waste can be used directly by being burnt instead of coal or gas to provide heat. The heat can then be used to produce steam. This in turn is used to produce electricity. This produced in the same way as it is in a traditional coal-fired power station. (see Coal-fired power station fact sheet). The waste can also be used to generate methane gas to fire a power station. Another fuel that it can make is the liquid ethanol.
Biomass is ideal for use in cogeneration with processing plants (e.g. sugar cane mills), solar power or wind power.
Biomass resources include:
- Agricultural Crops
- Animal Waste
- Agricultural Residues
- Forestry Crops
- Forestry Residues
- Industrial Waste
- Municipal Solid Waste (MSW)
- Sewage
Bagasse, the waste material from sugar cane, is used in this way to produce electricity in a number of Queensland sugar mills.
Energy can be gained from biomass either directly or indirectly. It can be burnt to produce heat or converted into a gas or a liquid (such as ethanol). This includes:
Under normal circumstances, the organic material that makes up biomass would decompose slowly returning all its elements, including carbon in the form of methane and carbon dioxide, to the environment. In this way nature recycles everything. This recycling process, known as the carbon cycle, maintains the balance of carbon in the environment. Using biomass as a fuel accelerates this process. For this reason biomass is considered to be the only renewable source of carbon based fuel.
Locations of biomass generators
The construction of Rocky Point Sugar Mill at Woongoolba, near Beenleigh in South East Queensland, was completed in 2002. This plant produces energy in the form of ethanol during the sugar crushing season.
Click here to view a diagram of the workings of the Rocky Point Sugar Mill, courtesy of the Stanwell Corporation.
Benefits and costs of biomass generation
Benefits
- Using biomass reduces methane gas emissions to the environment
- Biomass is a renewable resource, always available
- The use of biomass fuels produces lower sulfur emissions than coal
- Burning biomass produces, on balance, lower emissions than burning coal
- Using the biomass is an efficient use of waste products
- Reduces the need for waste dumps./li>
Costs
- Much larger volumes of biomass are needed to produce the same amount of electricity as fossil fuels
- Energy and food crops may compete for the same farmland
- Biomass is still a comparatively expensive energy source for electricity production.
