Worldwide, interest in using biomass for energy is increasing because of:
- Political benefits – eg the reduction of dependency on imported oil;
- Employment creation – biomass fuels create up to 20 times more employment than coal and oil;
- Environmental benefits such as mitigation of greenhouse gas emissions, reduction of acid rain, and soil improvement.
Already, around 12% of the global energy required is generated by combustion of biomass sources, which vary from wood to animal by-products and black liquor. A wide variety of appliances is used to convert this biomass into useful energy.
Many countries have abundant resources of unused biomass readily available |
In developing countries, around 35% of the energy used originates from biomass, but most of this is for non-commercial use in traditional applications (such as cooking). In a country such as Nepal, over 90% of the primary energy is produced from traditional biomass fuels.
In industrialised countries, the total contribution of biomass to the primary energy mix is only 3%. This mainly involves the combustion of commercial biomass fuels in modern devices – for example, woodchip-fired cogeneration plants for heat and power. Other applications are domestic space heating and cooking, industrial heat supply, and large-scale power
generation in coal-fired plants.
View inside a step grate boiler (Courtesy of TNO, Netherlands) |
Combustion is the most common way of converting biomass to energy. It is well understood, relatively straightforward, and commercially available, and can be regarded as a proven technology. However, the desire to burn uncommon fuels, improve efficiencies, cut costs, and decrease emission levels continuously results in new technologies being developed.