Wood Energy

Wood Energy

Wood is mostly used as a source of energy in most agro- industries. In the tobacco industry, they use firewood for drying of flue cured tobacco, and in tea estates, where wood is used extensively to heat boilers. Wood fuel is managed by pruning, thinning, coppicing, lopping and pollarding. In Zimbabwe, the government has allocated special rights to the Zimbabwe National Traditional Healers Association, setting aside pieces of land to grow and maintain original plants which were used for medicinal purposes. Wood can be treated biologically through using ash or soot to avoid pests and insects destroying it.

Wood fuel may be available as fuel wood, charcoal, chips, pellets and sawdust. However, combustion of wood leads to greenhouse gas emissions which is a threat to climate change. Any energy that comes from using wood as a fuel source may be referred to as wood energy. While the term is not a common one, it accurately describes the fuel source and the benefit. Wood energy was once the dominant source of energy used in the world, but has since been replaced by fossil fuels in most areas. Still, there are many people who currently depend on wood as a fuel source for energy in a number of different ways.

Biomass

The African continent has an abundance of biomass resources. About one fifth of the world’s tropical forests and one third of its tropical grasslands are in Africa. Also, the continent has a big population of cattle whose dung is good material for producing power. Biomass is responsible for about 50 – 90 percent of the total energy supply of many African countries. Biomass resources include wood waste, waste from agricultural crops such as maize stalks and grain husks, solid waste, animal waste from food processing, aquatic plants and algae. Biomass can be converted into energy by treating it with chemicals or bacteria. Biomass is fermented to produce fuel ethanol. Chemical treatment of biomass produces such fuels as synthetic gas, methane and fuel oil, when biomass is treated with bacteria; it yields alcohol, chemicals or methane.

Advantages of biomass

  • Creates employment
  • Produces fertilizers as by-products
  • Ideal for rural communities
  • Cheap and renewable if replanted or re-a forestation takes place

Disadvantages of biomass                       

  • Leads to deforestation, desertification and soil erosion.
  • Pollutes the environment.
  • Agricultural biomass leads to competition for land with other crops.

Biomass use in Zimbabwe 

Biomass, in the form of wood fuel, provides the bulk of total energy supply, and most rural areas are facing fuel-wood shortages as a result of agricultural land use and unsustainable harvesting. Demand for wood fuel already exceeds supply in Manicaland, Mashonaland East, the Midlands and Masvingo provinces, which are heavily populated. Mashonaland Central and Matabeleland North are fast reaching the same situation. It is estimated that more than six million tonnes of wood fuel are consumed annually when the sustainable output of natural forests is 4.6 million tonnes. This translates to a loss of 330,000 hectares of forest area, or over 60 million trees per year. At present the annual tree-planting rate is only 10 million trees.

For the foreseeable future, wood fuel will continue to be used for cooking and space heating by rural and low-income urban households. It is therefore necessary for the government of Zimbabwe to establish an institutional and funding framework for developing and implementing strategies to deal with the wood fuel crisis. Commercial forests comprise 81,000 hectares of pine, 24,000hectares of eucalyptus and 13,000 hectares of wattle (Source: Zimbabwe Energy Policy). Forest residue from commercial forests is estimated at 70,000 tonnes and has potential for the generation of 150MW power and the creation of a more formalized wood fuel and charcoal market. Three companies Allied Timbers, Border Timbers and The Wattle Company – generate over 40,0000m3 of pine waste per year.