Fuel consumption of timber harvesting systems in New Zealand
Fuel is a major cost in timber harvesting operations. Changes in fuel cost are also typically used by forestry companies in New Zealand to adjust unit harvesting rates. There is however no benchmark on fuel consumption rates for the different harvesting systems to assist optimizing the design of operations. Seventeen g round-based and 28 cable logging crews in New Zealand were surveyed on annual fuel consumption, production, stand and terrain attributes, type and number of machines used and their kW rating. The average rate of fuel consumption was 3.04 lt/m3 and 0.15 lt/ kWh for ground-based systems, and 3.18 lt/m3 and 0.09 lt/kWh for cable yarder systems. There was no significant difference between the two groups for the average rates of fuel consumption in lt/m3, but ground-based system were significantly less energy efficient (more lt/kWh) than cable yarder systems. The average rate of fuel used per unit volume harvested decreased with total annual system production. Rates of fuel consumption in lt/kWh are influenced by the type of harvesting system used, total productio n, number of machines used, average machine power, slope, directions of pulling during extraction and surface moisture conditions during harvesting. Using standard published machine costing spreadsheets, fuel costs per unit volume of wood harvested was approximately 15% of the total harvest system cost.