Improving drying technology for forest chips: LUKE

Finnish researchers are currently studying a more efficient means of drying wood chips, one that is said to be efficient, mobile and suitable for drying various materials.

The artificial dryer, in the form of a shipping container, is developed by Finnish company SFTec Oy and the Natural Resources Institute Finland (Luke).

The project highlights the complexities of drying technology. A wide range of artificial dryers on the market run into technical challenges especially when it comes to eliminating moisture in fuel chips, which affects heating value and the amount of energy obtained from the chips. Damp forest chips burn imperfectly, which also means that emissions increase.

Forest chips are used in heating buildings, in small-scale district heating plants and in heating and power plants for towns and industry. They are collected from young forests, from logging residues in regeneration fellings and from stumps and rot damaged trunks.

The first drying test has been carried out using stem wood chips.

Researchers are currently calculating supply chain costs based on artificial drying and comparing them with the traditional approach.

“The decisive issue is the operating cost and whether the benefits achieved through drying cover the costs it incurs,” says Juha Laitila, principal research scientist at Luke. He does not say if the artificial drying technology is now economically viable.

However the dryer´s energy consumption is the biggest challenge, which may be solved if excess heat from hydroelectric power plants and closed landfill sites can be channeled for drying wood chips.

Waste heat from heating plants could also be used to run the dryer. This could translate into a recycling loop where the forest chips would heat same heating plant whose surplus heat has been used to dry the forest chips.

In spring, Mikkone Oy, which is both a producer and an end user of wood chips, will test run the dryer.

Managing Director Mikko Sirviö says, “The drying time for forest chips can decrease from months to hours or even minutes. At the same time, quality will improve, as rot no longer has time to affect the wood.”