Waipa Sawmill co-generation case study
The Waipa sawmill near Rotorua has been generating its own electricity for over 50 years, cutting its costs and returning power to the national grid.
A large sawmill produces a lot of sawdust, bark and off-cuts. At Waipa, these byproducts provide fuel for a ‘cogenerator' that produces heat for timber processing, as well as extra electricity that is sold to TrustPower. In a typical month, the sawmill spends about $40,000 on electricity but also generates and sells $20,000 worth - essentially halving its power bill. Chief Financial Officer Paul Laing of Red Stag, the company that owns the sawmill, says the electricity savings could be as much as $1 million a year. While the cogeneration plant's main purpose is to reduce the sawmill's power bill, there are plans to enable it to sell 100% of the electricity generated on days when the sawmill is closed.