How technology can improve the efficiency of excavator-based cable harvesting for potential biomass extraction - A woody productivity resource and cost analysis for Ireland

Two cable logging systems were reviewed to compare the efficiency of potential biomass extraction from remote forest sites in Ireland based on productive machine hour (PMH) and unit cost of operation (€/m3). Three operational scenarios (SC) were analysed where SC I was a three man crew operation (choker setter, the carriage operator and unhooking chokers). SC II was a variation of this with a two man crew operation. SC III was operating radio controlled chokers there was a two man crew (choker setter and carriage operator). The study aims to assess how operations in Ireland perform against previous known cable studies to determine whether the cost of timber extraction on remote forest sites inaccessible for mechanised felling, has a future given the increased demand for wood fibre in Ireland, both from the sawmilling industries and the wood for energy sector. The volume per PMH was recorded at 17.97 for SC I, 15.09 for SC II and 20.58 m3 for SC III. The difference in productivity versus SC III remote controlled chokers is 5.49 m3/PMH for SC II crew and 2.61 m3/PMH for SC I. The decrease in total volume extracted from SCs I and II versus SC III was recorded at 15.69 m3 (15%) and 32.97 m3 (36%) product respectively. In value terms, the unit cost (€/m3) varied from 6.29 (SC I) to 6.43 (SC II) to 4.57 (SC III). When looking at the production unit costs of normal wood energy supply chains in Ireland, the figures are similar ranging from 3.17 €/m3 to 8.01 €/m3. The value of the end product of course will always determine which market the eventually goes to but given that cable log wood fibre has been unthinned and unmaintained then the biomass
sector may be an ever increasing demand point in the search for increased woody biomass
given that the unit costs can be competitive with other wood energy supply chains.