A sawmill in Victoria is saving $269,000 a year on LPG by burning waste wood to heat the kilns used for drying wood.
Excess steam is converted to electricity, giving additional savings of $10,000 a year.
Reid Brothers Sawmillers have been operating a sawmill at Yarra Junction since 1940. The company processes around 17,500 cubic metres of timber a year, of which 5000 cubic metres is kiln dried.
They were using LPG in the boilers supplying the heat used in their kiln. They were also paying over $1200 a month to send waste timber material to landfill.
As the price of LPG rose, they saw an opportunity to cut costs and reduce waste by installing a wood-fired boiler.
In 2005, a 1 MWth (thermal) system was commissioned. The system burns 70-80 tonnes of mill waste weekly to heat the kilns.
The waste comprises sawdust from the sawmill, clean-up material, some green material and occasionally material from other timber processing businesses.
The moisture content of the feedstock ranges from about 10 per cent to 50 per cent.
An Organic Rankine Cycle electricity generation system uses surplus steam from the boiler to generate electricity. Local company gT Energy Technologies (gTET) retain ownership of the electricity generator and sell electricity to Reid Brothers at a discounted rate. Any excess power is sold to the grid.
- Wood-fired boiler capital and installation cost: $360,000
- Wood fired boiler annual operation and maintenance: $15,000
- LPG – used 360,000 litres/year; additional kilns increased use by 25% to 450,000 litres/year. Average cost of LPG of 60 cents/litre: $270,000
- Annual cost of waste wood disposed to landfill: $14,000
- Savings: $284,000
- Net savings less cost of boiler operation/maintenance: $269,000
- Payback period for boiler: 1.3 years
- Savings on electricity: Approx. $10,000 a year
How the system works
- Once a day, sawmill residue is loaded into the boiler hopper.
- Belts and moving floors allow a controlled quantity of wood waste to be fed into the combustion chamber.
- A small quantity of ash is automatically removed from the boiler and deposited in an ash bin.
- Water is piped into the combustion chamber and heated, creating steam.
- The steam is fed into the timber-drying kilns.
- Temperature and biomass feed-in rates are centrally controlled.
Find out more
Read the full case study: Sawmill powered by wood waste
Reid Brothers Sawmillers Pty Ltd
Lt Yarra St, Yarra Junction VIC 3797
Phone: 03 5967 1005