Production and operations of forest energy

Blas MOLA-YUDEGO, Heli KYMÄLÄINEN, Daniela NOUSIAINEN

Summary

Forest is a valuable resource of wood biomass for bioenergy production. How can we extract this biomass from the forest? What are the factors affecting harvesting operations? And what are the limitations of biomass harvesting?

All parts of tree can be used for bioenergy. Biomass can be acquired from forest in form or whole trees, stems, branches, but also stumps or tree tops. This material can be transformed into more compact and better storagable products, such are chips, fuel wood or pellets. When and where this can be done? That is what planning of harvesting operations which are part of supply chains, is for. Depending on, for example, accessibility of harvestable biomass, its volume and concentration, type and quality, forwarding distances or technical requirements from machinery, norms or even weather conditions, harvesting operations are planned. Such process usually starts with tree felling by harvester or chainsaw, which is followed by transportation of the tree from the felling site, or its processing at the stand. It is delimbed, tree tops are removed and stump is measured. Transportation of the felled tree or its assortments can be done using great amount of various techniques and machines.

From forwarders and forest tractors with winch, to skidders, forest horses and if terrain conditions require, specially-adapted bogies can be used (caterpillars, climbing, walking bogie) and even cable yarding is used. Skidding (or also known as bridling) and hauling of timber are types for transportation for short distances. Long distance transportation is performed by trucks, sometimes by trains. as well. In case of chips´ transportation, containers installed on trucks are used. Chipping of biomass can be done at the roadside or storage place, rarely even at the felling site. Harvesting operations are significantly affected also by characteristics of the raw biomass. High moisture content of the material leads to higher transportation costs. Weight, Volume, bulk density or mass density also affect the harvesting operations in terms of planning the space, machinery, logistics, etc. Energy density tells us how much energy we can “sell” in the future from the certain volume of biomass. This everything and more should be taken into account when designing and securing biomass procurement.

Objectives

This session focuses on:

• To review the most common forest operations for the procurement of forest biomass.
• To understand the links between the raw material characteristics and the forest operations associated
• To get familiar with the machinery used in the procurement and logistics of wood biomass

Materials

Forest operations for the procurement of wood biomass [PDF]

Lecture videos [videos]

• Introduction and tree biomass basics
• Preparation, felling, processing, stump excavation
• Bridling and hauling
• Chipping and storage
• Transportation
• Limitations
• Raw material characteristics

Readings

Röser, D., Mola-Yudego, B., Sikanen, L., Prinz, R., Gritten, D., Emer, B. & Erkkilä, A. (2011). Natural drying treatments during seasonal storage of wood for bioenergy in different European locations. Biomass and Bioenergy, 35(10), 4238-4247 [PDF]

Video database of forest machines in biomass procurement operations [YouTube] ForestEnergy Portal