How is biomass energy used?

One of the advantages of biomass is its versatility. It can be burned directly, or converted into a gas or oil, to generate electricity (biopower) and heat. It can also be converted into liquid fuels (biofuels) for our transportation needs.

There are several ways of turning biomass into electricity and heat, including direct combustion, co-firing, gasification, pyrolysis and anaerobic digestion.

Direct Combustion
The simplest way, and oldest way, of generating electricity from biomass is to burn it. This is called direct combustion. Direct combustion (or “direct-fired”) systems burn biomass in boilers to produce high pressure steam. This steam turns a turbine connected to a generator. As the steam causes the turbine to rotate, the generator turns and electricity is produced. Most of the world’s biomass power plants use direct combustion. In some cases, the steam from the plants is also captured to heat water and buildings. These are known as cogeneration facilities.

Although this technology is dependable and proven, its efficiency is limited. Direct combustion systems typically have thermal efficiencies around 20 per cent. These efficiencies can be increased through cogeneration.

Co-firing
Co-firing involves burning biomass, along with coal, in traditional power plant boilers. This is considered to be one of the most economic ways to produce electricity from biomass, because existing power plant equipment can be used without major modifications. Some coal-fired power plants in North America use this technology to help reduce the use of coal and, thereby, lower emissions of carbon dioxide, sulphur dioxide and nitrogen oxides. Co-firing also allows biomass to be converted to electricity at a higher thermal efficiency in the 33 per cent to 37 per cent range.