Sawmills find renewable energy - and cost savings - in wood waste
6 August, 2007
A North Island sawmilling company recently switched from electricity to wood residue for its boiler fuel and has found it to be a very cost effective energy option.
The company previously used electrically heated kilns to dry timber, but it recently phased out the electrical system in favour of kilns heated by a central boiler that burns wood shavings from the milling process.
The company produces 39% of the shavings required to run the boiler and buys the rest from other suppliers. It is considering installing a multi-fuel boiler in the future, which would burn other by-products such as sawdust and bark, reducing the need to buy fuel from elsewhere.
Wood residue now accounts for 84% of energy usage at the company’s mills, with electricity providing the rest. However, the cost of wood residue represents only 10% of the total energy bill, while electricity costs represent 90%.
The switch to this renewable energy resource has the potential to save the company over $300,000 a year in energy costs.
Read the full case study (PDF 454KB)
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Sawmill considers energy centre options
6 August, 2007
TDC Sawmill is looking at ways to generate steam energy for a proposed energy centre at its fortress mill in Whangarei.
The Mill produces greenwood timber but TDC plans to install driers so the mill can increase its output by also turning out dried and planed timber. The new driers would require an energy centre.
A feasibility study by Process Developments Limited identified five options for the energy centre, all involving wood-fired boilers. Some options also included cogeneration or gas.
As well as capital and running costs, the study covers a range of engineering issues and recommends preferred technologies for the site.
The feasibility study will help TDC to identify the most suitable option.
Read the full case study (PDF 98KB)
Energy Use in the New Zealand Wood Processing Industry (2002)
Forest Research (now Scion) produced this report providing an overview of energy use within the NZ wood processing sector in 2002. The wood processing sector supplied over 50% of its own energy in the form of biomass (wood process residues and black liquor). Electricity represented 18%, natural gas represented 17% and geothermal steam represented almost 10% of the total energy use.
The 2002 survey indicates that the total energy use by the wood processing sector had increased by over 40% from the previous 5 years. This increase could be attributed to marked increases in production with a 30% increase in sawmill production and a 40% increase in panel production, and a significant expansion of the use of wood processing residues for energy production.
Full report [PDF 659kb].
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Sawmill leaves gas bill for dust
18 July, 2007
Kiwi Lumber’s sawmill at Dannevirke has cut its gas bill by turning its leftovers – sawdust and wood shavings – into energy.
The sawmill had been using a gas fuelled boiler for drying timber, but the rising cost of gas led it to look for a cost effective and sustainable alternative.
Using wood residue instead of gas to fire the boiler saves the sawmill 19GWh in gas a year. Other benefits include fewer loads to the landfill and a saving of 2,280 litres of water a day.
A feasibility study put the sawmill’s waste by-product in a new light. It found that 96% of the sawmill’s energy demand could be met by powering the sawmill’s kilns with water heated by burning sawdust and wood shavings.
Management compared the cost of installing a wood residue fired boiler system with the savings from not using gas. The figures looked good.
Having made the switch, wood residue now provides 89% of the sawmill’s energy needs, with electricity covering the rest.
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