Wood energy options for industry
Wood fuel is usually turned into energy (i.e. heat or electricity) through burning (combustion). But there are also a number of alternatives which are becoming more common like gasification where syn-gas is used in cogeneration plants, co-firing or as a clean heat fuel.
An industrial boiler consists of a furnace and a heat exchanger (boiler tubes). It uses furnace heat from the flue gas and transfers it in the heat exchanger to produce hot water or steam. The furnace type determines the type and quality of the fuel that can be used in the boiler. The different furnaces available for industrial purposes include:
- Fixed bed furnaces which include grate furnaces (used for burning fuel with a medium level of moisture content) and underfedstokers which are used for small to medium scale operations
- Fluidised bed furnaces for large scale operations
- Dust furnaces which are used for small, dry particles like sawdust
- Wood pellet boilersspecifically designed for burning wood pellets
Cogeneration is the combined production of heat and electricity. In a cogeneration plant, the waste heat from electricity generation is used as process heat on-site (e.g. for kiln drying or timber treatment). Because of this, cogeneration can be a very efficient method of energy production. Steam turbine is the standard cogeneration technology but other technologies like gasification also exist.
Cogeneration is a specialised area, so expert advice should be sought to assist in deciding whether it is right for your business.
Co-firing (or co-combustion) is when operations are run by burning a combination of wood and other fuel such as coal. Fuel ratios are critical in this process and the possibility of co-firing needs to be assessed on a case-by-case basis.