COFORD has supplied us with ideas on how to harvest coppiced willow, and store the product to meet customer requirements.
Short rotation willow coppice is increasing in many countries due to its potential for use as a source of woody biomass. Willow is harvested when the stems have no leaves, which coincides with the wet period when the ground is very soft. When harvested, willow moisture content is approximately 55 to 60%. Harvesting yields are about 50 tonnes per hectare. Pieter Kofman of COFORD has produced two technical notes (COFORD Connects - Harvesting & Transport, No. 29 and 30) that explain willow coppice harvesting and storage. Three harvesting systems are presented:
The different harvesting methods are compared against each other considering the area to be harvested, cost, harvester productivity, logistics, drying possibility, implications for conversion to a fuel, markets and investment costs. Agricultural harvesters still need some development before they can cope with the harsh woody material that they must cut.
In the Connects note on coppice willow fuel storage, different fuel sizes were examined in different locations. The results showed that the longer the size of the fuel, the better it dries. Smaller sized fuels stored outdoors did not dry, not even if they were covered. Storing the material indoors greatly increased drying rates. Drying was not found to be viable for large quantities of fuel. It was better to transport the material to the customer as soon as possible to prevent costly additional handling. Source: http://www.coford.ie/publications/cofordconnects/
Short rotation willow coppice is increasing in many countries due to its potential for use as a source of woody biomass. Willow is harvested when the stems have no leaves, which coincides with the wet period when the ground is very soft. When harvested, willow moisture content is approximately 55 to 60%. Harvesting yields are about 50 tonnes per hectare. Pieter Kofman of COFORD has produced two technical notes (COFORD Connects - Harvesting & Transport, No. 29 and 30) that explain willow coppice harvesting and storage. Three harvesting systems are presented:
- Whole-shoot harvesting – Manual, motor-manual (chainsaw or brushcutter), tractor-drawn equipment or self-propelled machines can be used. Mechanised systems lend themselves to larger felling areas. Large landing areas are required as the stems are left to dry on roadside. To achieve good quality chips from this brittle material, the machine must have sharp knives, a sharp anvil and precise feed speeds.
- Cut-and-chip – Tractor-mounted equipment and self-propelled machines are used. Most self-propelled machines are agricultural harvesters with modified cutting heads. Chips produced are very wet and need to be dried or transported immediately for burning. Chip quality is usually good.
- Cut-and billet – These are machines derived from sugarcane harvesters, and produce course chips. The larger piece size makes the material easier to store and dry.
The different harvesting methods are compared against each other considering the area to be harvested, cost, harvester productivity, logistics, drying possibility, implications for conversion to a fuel, markets and investment costs. Agricultural harvesters still need some development before they can cope with the harsh woody material that they must cut.
In the Connects note on coppice willow fuel storage, different fuel sizes were examined in different locations. The results showed that the longer the size of the fuel, the better it dries. Smaller sized fuels stored outdoors did not dry, not even if they were covered. Storing the material indoors greatly increased drying rates. Drying was not found to be viable for large quantities of fuel. It was better to transport the material to the customer as soon as possible to prevent costly additional handling. Source: http://www.coford.ie/publications/cofordconnects/