Converting Wood Residue
Wood residue can be converted into energy in several different ways. It can be burned directly to produce steam and electricity. In cogeneration facilities, the steam is then used to create usable heat.
New technologies have been developed that involve gasification of biomass fuels. In this process, wood residue is converted to gas. The gas is then used to heat air, which passes through a turbine to create electricity.
One major advantage of gasification systems is that electricity generation is very efficient – up to 30% to 50 % more efficient that conventional steam generation. These efficiencies are realized by using a gas engine or gas turbine in a combined cycle with a steam turbine. Another advantage is that the gases produced contain less particulate matter and can be used directly in existing boiler facilities to reduce fossil fuel usage and reduce overall emissions. This also reduces the costs associated with emission control technologies.
The main disadvantage of advanced gasification systems is that the initial capital costs can be significantly higher than for conventional systems. However, in B.C. there are numerous potential sites that would be suitable for small gasification systems with capacities ranging from 1 to 5 MW. These could include sawmills and other forest operations that are too far away from larger generation facilities to make it economical to transport the wood residue there.
Pyrolysis is another technology that can be used to create electricity from biomass. It is a closed-system heating process that produces bio-oil, which can then be used to fuel generators to produce electricity.
