The promotion of electric energy production from solid biomass by the Austrian government has lead to a boom in the construction of new combined heat and power plants. The current total demand for wood chips in the research area for energy purposes is 70 400 m 3 of loose volume chips per year. The expected increase in demand due to these new plants is more than 4 times greater than current demand: up to 302 700 m 3 of loose volume per year. Even if the energy wood feedstock potential is satisfactory, the design of the supply chain is still unresolved. The aim of this study is to give decision-makers a base for further development. To accomplish this, we designed and tested four different supply scenarios: one for 9 plants and one for 16 plants. The scenarios were developed using a combination of geographic information systems (GIS) and linear programming methods. The results indicate that direct transport of solid fuel wood as round wood and chipping at the plant is the cheapest supply system with a resulting cost of 5.6-6.6 EUR/m 3 loose. Using harvesting residues can only be recommended for large plants because of poor fuel quality. In this case, residues would be chipped at or near the landing, piled and transported via self-loading trucks at a cost between 8.4 and 9.1 EUR/m 3 loose. In order to meet increasing demand and to ensure a continuous supply, especially during the winter and spring seasons it is necessary to optimize the supply chain by including storage terminals. However, using terminals and increased demand both lead to higher logistical costs. For example, if the total volume is handled via terminals, the average supply costs including storage will increase by 26%. Higher demand increases the costs by 24%.

Round wood supply in Austria is often affected by different factors such as bottlenecks or oversupply due to changing market, weather and road conditions. An additional factor impacting the complex wood supply chain is the rising transport costs from the landing to the sawmill. Logging trucks are the primary transportation technology used from the forest to the customer's site. The objectives of this study were to analyze the actual situation and characteristics of typical trucking activities for round wood supply from the region to an Austrian sawmill. The study used time and fuel consumption, proportion of travel on forest roads and average speed on different functional road classes to estimate productivity and costs. Data collection including GPS-tracking was done using fleet management equipment built into the driver's cabin. The GPS-routes were analyzed in ArcGIS 9.3 based on the national road network and its attributes. The sawmill studied with a yearly demand of 600,000 m 3 round wood was located in southern Austria. In total, more than 2,000 round trips operated by seven logging trucks recorded close to 100,000 km. The transport distance from the forest to the sawmill averaged 51 km. The average share on forest roads within a route to the sawmill was 14.2% with an average speed of 13.5 km/h, whereby the forest road is defined as road with minor importance. Transport costs from the forest site to the sawmill with a truck and trailer were € 11/m 3 solid timber based on an average load size of 25 m 3 . An average 0.77 l of diesel fuel per kilometer was consumed during a round trip including all work phases. A trip to an interim storage location consumed 2.05 l/km due to the number of work phases without driving distance.

Cable yarding continues to be an efficient and effective harvesting system for the extraction of timber on steep terrain. Modern European silvicultural strategies result in smaller harvest areas, lower extraction volumes and a shift from clear-cut to thinning operations or single tree extraction. Yarder installation time has, especially as a proportion to the extraction time, increased significantly, resulting in higher extraction costs. This study recorded the set-up and take-down time of 79 cable yarder installations. Another 76 installation times were taken from previously published time studies, for a total sample size of 155. The factorial study design differentiated uphill-or downhill yarding, yarder size and whether or not it was the first installation at a landing, or subsequent parallel installation from the same landing area. The covariates recorded were corridor length, terrain slope, number and height of intermediate supports, and number of forest workers. Both a set-up and take-down time models were developed. This will help estimate future cable installation time requirements, and more importantly, provide improved cost estimates for the new silvicultural treatments.

A team of international specialists has developed a new guide for conducting forest work studies. The guide is a quick how-to manual designed for the field researcher, and it may contribute to the international harmonization of work-study methods. This endeavor was supported by the European Union through COST Action FP0902; however, the author team was not limited to European scientists, it was world-wide. The draft was reviewed by three international experts external to the team and to the action. Two provisional versions were administered to a test group of students, who elected the current version. Feedback was sought after publishing, through an online survey. Ninety-three researchers responded to the survey. The largest majority of respondents believed that the guide was state-of-the-art and that they were able to do a better job after reading the guide. The guide is available for free download from the Forest Energy Portal (www.forestenergy.org).

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Determining the moisture content of naturally dried fuel stock without frequent measuring is a problem still unsolved. Modelling moisture content based on automatically captured meteorological data could provide a solution. An accurate model would allow the drying period and the point of chipping to be optimised. For the experimental study, a metal frame supported by load sensors and loaded with 17 tons of logwood was set up next to a meteorological station. A multiple linear regression model was used to link meteorological and load data to provide a formula for determining the moisture content. The pile dried for a period of 14 months (average temperature of 7.3 °C, a humidity of 81%, and 777 mm of rainfall). The overall moisture content dropped from 50.1% to 32.2%. The regression model, which based on daily means and sums of meteorological parameters, provided a mean deviance from the observed curve of -0.51% ± 0.71% within the period of investigation. Relative humidity was found to be most important parameter in drying. Increased moisture content resulting from rainfall greater than 30 mm per day reverted back to pre-rainfall values within two to three days, if no other rainfall events followed. Covering the pile would have a positive effect on the drying performance. In terms of economic benefit it could be shown that natural drying is beneficial. Overall this study shows that meteorological data used in site specific drying models can adequately predict the moisture content of naturally dried logwood.

Controlling and organizing the complex forest-to-consumer supply chain of wood fuels is a challenging task, especially for the chipping and transport processes. Truck mounted chippers and transport trailer-trucks must be scheduled to minimize delay to be profitable. Job management within the supply chain, including machine activity based controlling, offers a new way to increase efficiency and productivity. However, detailed data are required to detect and analyze potential gaps and improve forest fuel supply. Generally, data regarding the wood fuel supply chain process are obtained from extensive time studies that are based on a specific process step. Although time studies can detect details during the production of forest fuels, they only describe certain time frames. Long-term data that are recorded during the entire year could encompass seasonal and short term effects. This study aims to monitor the forest fuel supply processes (semi-automated), specifically regarding time and fuel consumption. Large data sets were automatically and efficiently gathered with little effort by drivers and operators. Data were recorded with fleet management equipment for more than 14 months. Vehicle data, including GPS data, were logged at an interval of one minute. Data management was conducted in a pre-configured database that contained pre-defined reports and were run by the Institute of Forest Engineering, Vienna. Work step assignments were implemented with Structured Query Language (SQL)-routines by using the raw machine activities data and GPS. The chipping and transport activities of more than 240 loads were analyzed by focusing on fuel consumption, time needed and traffic. The average distance between chipping sites and plants was approximately 54 kilometers. Fuel consumption from transport reached 50 l/100 km. The chipping unit reached a productivity of 12.8 odt/PSH15 and had a fuel consumption of 58 liters per operating hour.

Abstract:The objective of this case study was to develop and test a specific survey protocol for monitoring tensile forces for winch-assisted harvesters and forwarders with a mounted or integrated constant-pull capstan winch technology. Based on the designed survey protocol, the interactions between work phases, machine inclination, and tensile forces in typical work conditions were analysed. The established workflow, including equipment and the developed analysis routines, worked appropriately and smoothly. The working load on the cable during the study did not exceed 50% of the maximum breaking strength. A maximum tensile force peak at 56 kN was observed during delays for the forwarder, and a peak of 75.5 kN was observed for the harvester, both of which are still within the safe working load when considering a safety factor of two.