Analysis of three forest chippers: productivity, costs and GHG emissions in Northern Spain

The study and development of efficient forest-fuel systems with different species in different climates has become one of the biggest challenges in forestry. The aim of this study was to evaluate and compare productivity, costs and greenhouse gas (GHG) emissions of three different chippers in thinning, using a whole tree harvesting system. The relation between chipper productivities and GHG emissions was also examined. Trials were conducted in young pine stands in Northern Spain. Stand inventories before and after the thinning, plus a work sampling time study (64.81 h in total) of each chipper was conducted to calculate productivity. All work elements were recorded on a fixed time interval (1 min) with a hand-held field computer. Costs with regards to productive and total time were also calculated. In order to calculate the GHG emissions produced by the process of obtaining chips from timber in the forest, the three chip production systems were evaluated. The system boundary considered included the chipping, felling and forwarding phases. The amount of kg CO2e emitted was estimated from the productivity and fuel consumption data of each machine involved in the process. Results showed that chipper productivities varied between 5.78 and 7.29 odt SMH−1 (oven dry tonnes per Scheduled Machine Hours). Furthermore, the two more powerful chippers achieved a productivity not so different to the productivity of the lowest powered chipper, due to the former's organizational delays and poor forestry planning in that these chippers had to wait for replacement containers before continuing chipping at roadside, while the less powerful machine chipped continuously onto the ground, highlighting the importance of operation management. Chipping costs were 3.03, 3.10 and 4.06 € MWhchip−1. The GHG emissions evaluated were 7.09, 8.41 and 7.6 kgCO2e MWhchip−1, with the chipping phase being the greatest contributor to GHG emissions in two of the systems studied. Energy balance varied between 2.92 and 4.02%, demonstrating high efficiency since an energy input of only 2–4 % of the energy produced was required. Studies of this kind are essential to identify those factors which affect productivity and how they may influence costs and GHG emissions, in order to improve forest-fuel systems from an environmental point of view.

[1]  J. V. Belle,et al.  A model to estimate fossil CO2 emissions during the harvesting of forest residues for energy—with an application on the case of chipping , 2006 .

[2]  Dominik Röser,et al.  Chipping operations and efficiency in different operational environments. , 2012 .

[3]  Alberto Assirelli,et al.  Effect of piece size and tree part on chipper performance , 2013 .

[4]  Jori Uusitalo,et al.  Characteristics and Significance of a Harvester Operators’ Working Technique in Thinnings , 2004 .

[5]  Kevin McDonnell,et al.  Forest Biomass Supply Chains in Ireland: A Life Cycle Assessment of GHG Emissions and Primary Energy Balances , 2014 .

[6]  Juha Laitila,et al.  Greenhouse gas emissions of forest bioenergy supply and utilization in Finland , 2014 .

[7]  Yolanda Ambrosio,et al.  Recovering of forest biomass from Spanish hybrid poplar plantations , 2011 .

[8]  Leif Gustavsson,et al.  Biofuels from stumps and small roundwood - Costs and CO2 benefits , 2008 .

[9]  Margareta Wihersaari,et al.  Greenhouse gas emissions from final harvest fuel chip production in Finland , 2005 .

[10]  Clara Valente,et al.  Greenhouse Gas Emissions, Energy Use, and Costs—Case Studies of Wood Fuel Supply Chains in Scandinavia , 2012 .

[11]  Leif Gustavsson,et al.  Costs, CO2- and primary energy balances of forest-fuel recovery systems at different forest productivity , 2010 .

[12]  Raffaele Cavalli,et al.  WOOD CHIPPING SERVICE: AN ANALYSIS APPROACH IN NORTHEASTERN ITALY , 2007 .

[13]  Juan Majada,et al.  A spatial analysis of woodfuel based on WISDOM GIS methodology: Multiscale approach in Northern Spain , 2015 .

[14]  D. Timmons,et al.  Biomass energy from wood chips: Diesel fuel dependence? , 2010 .

[15]  Clara Valente,et al.  LCA of environmental and socio-economic impacts related to wood energy production in alpine conditions: Valle di Fiemme (Italy) , 2011 .

[16]  Rien Visser,et al.  Analyzing and estimating delays in wood chipping operations. , 2009 .

[17]  Leif Gustavsson,et al.  Comparative analysis of wood chips and bundles - costs, carbon dioxide emissions, dry-matter losses and allergic reactions. , 2010 .

[18]  Richard J. Murphy,et al.  Energy and greenhouse gas balance of the use of forest residues for bioenergy production in the UK. , 2011 .

[19]  Robert Blessing Mangoyana.  Bioenergy from forest thinning: Carbon emissions, energy balances and cost analyses , 2011 .

[20]  Bruce R. Hartsough,et al.  A survey of Italian chipping operations , 2001 .

[21]  A. Asikainen,et al.  Comminution of Logging Residues with Evolution 910R chipper, MOHA chipper truck, and Morbark 1200 tub grinder , 2013 .

[22]  Karl Stampfer,et al.  Current state and development possibilities of wood chip supply chains in Austria , 2006 .

[23]  N. Magagnotti,et al.  Determining the impact of some wood characteristics on the performance of a mobile chipper , 2011 .

[24]  L. Desrochers,et al.  The economics of chipping logging residues at roadside: A study of three systems , 1993 .