Technology of biofuel production from slash in clear-cuts [of] spruce stands | Biokurināmā sagatavošanas tehnoloģija no mežizstrādes atliekām kailcirtes izstrādāšanā egļu mežaudzēs
2009
Lazdans, V., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Lazdins, A., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Zimelis, A., Latvian State Forest Research Inst. Silava, Salaspils (Latvia)
This article represents results of research project ”Extraction of logging residues at LVM (Latvian State Forests)” implemented in cooperation between Joint stock company ”Latvijas valsts meži”, SKOGFORSK (The Forestry Research Institute of Sweden) and Latvian State Forestry Research Institute ”Silava”. The article is covering issues related to results of comparison of two mechanized harvesting methods - with collection of slash for biofuel production and without biofuel production, when branches and tops were compacted in strip-roads. The study implemented in November, 2005. A scope of the study was to estimate prime costs of solid biofuel production from slash in clear-cuts and to evaluate different working methods and influencing factors related to harvesting and forwarding of slash. Other stages of production, like comminution and road transport of chips were addressed as well. This particular article is targeted to results obtained in spruce dominant forest stand. Results of the study demonstrated that productivity of harvesting without biofuel production is 38.3 m**3E0-hE-1 and with biofuel production - 40.0 m**3E0-hE-1, which means that collection of slash in piles between assortments instead of packaging into strip roads increases productivity of harvester by 4%. Productivity of roundwood forwarder without biofuel production was 22.6 m**3E0-hE-1 and with biofuel production - 22.4 m**3E0-hE-1. Accordingly, collecting of slash decreased productivity of forwarding by about 1%. Productivity of forwarding of slash was 36 LV m**3E0-hE-1 (LV - loose volume). Prime costs of production and transport (forwarding – 500 m, road transport - 50 km) of roundwood assortments using ”biofuel” method were 3.38 LVL m**3, including 1.53 LVL harvesting, 1.19 LVL - forwarding and 0.66 LVL - road transport. Working without biofuel production increased harvesting costs by 0.14 LVL, but reduced costs of forwarding of roundwood assortments by 0.02 LVL, respectively, piling of slash between assortments instead of compacting into striproads reduced prime costs of roundwood assortments by 0.12 LVL or 3.5%. Prime costs of wood chips in calculation to current fuel price would be 3.93 LVL LV.mE-3, including 0.97 LVL - forwarding (500 m), 1.53 LVL - comminution and 1.43 LVL road transport of chips (50 km). Total fuel consumption to produce 1 LVm**3 of wood chips, excluding harvesting, corresponds to 1.89 kg of carbon emissions, in other words, 3% of carbon, which is recovered with biofuel is used in production cycle as emissions from fossil fuels and potential of reduction of emissions is 97%. High moisture level and ash content is found in the biofuel produced within the scope of study. Both values can be reduced by long term storage of slash in piles at roadside. This would lead also to increasing of net energy content in chips, which in the field study corresponded to 0.76 MWh LVmE-3. Results of the research demonstrated that technological system for the biofuel 111 production tested in the field trial is optimal for Latvian conditions. Reduction of costs of biofuel might be reached by optimization of comminution stage, for instance, by using bundling approach in clear-cuts, with long terrain transport distance, complicated storage (drying) or comminution conditions.
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