Case Study 2 Wood Waste to Energy (2013)

Energy Potential of Wood Waste: Wood waste, and wood by-products from industry that cannot be recycled or reused, are often recovered for energy use through combustion processes. Across the EU, it is estimated that wood waste from municipal sources contributes approximately 60 terawatt hours (TWh) from Europe‟s total biomass1 energy supply. Forestry by-products (such as black liquor, sawdust, and bark) contribute approximately 380 TWh to the total energy supply. For context, the total domestic biomass supply is approximately 1,000 TWh primary energy per year. Energy Recovery Options for Waste Wood: The use of waste wood for energy is high in countries such as the US, Canada and Europe. The following provides a broad overview of typical technology options: Technologies range from small boiler systems for directly heating houses and apartment buildings up to biomass boilers that efficiently supply heat through district heating networks. Wood waste, along with other biomass, is also used to generate electricity in combined heat and power plants (CHP). The waste heat produced is utilised in local and district heating networks or made available to industry as process heat. It can also be used to produce cooling for industrial purposes, for refrigerated warehouses or for cooling buildings (if combined with CHP, this is called tri-generation). Wood waste gasifiers may be used to generate heat and electricity. Depending on the characteristics of the combustion material and the capacity of the system, fixed bed, fluidised bed or entrained flow gasifiers can be used. The resulting syngas is then used to produce electricity in combustion engine systems or gas turbines.