Naslov
Energy Efficiency of Mechanized Thinning in Broadleaf Stand

Autori
Pandur, Zdravko ; Đuka, Andreja ; Papa, Ivica ; Bačić, Marin ; Janeš, David ; Vusić, Dinko

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), znanstveni

Izvornik
Natural resources, green technology & sustainable development / 3 / Radojčić Radovniković, Ivana ; Jakovljević, Tamara ; Petravić Tominac, Vlatka ; Panić, Manuela ; Stojaković, Renata ; Erdec, Dina ; Radošević, Kristina ; Gaurina Sarček, Višnja ; Cvjetko Bubalo, Marina - Zagreb : Prehrambeno-biotehnološki fakultet Sveučilišta u Zagrebu, 2018, 116-120

ISBN
978-953-6893-12-6

Skup
3rd Natural resources green technology & sustainable development-GREEN/3

Mjesto i datum
Zagreb, Hrvatska, 05.06.2018. - 08.06.2018

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
harvester, forwarder, energy return on investment

Sažetak
Efficiency of timber harvesting systems is traditionally expressed in time and/or monetary values per unit of a product. Unit cost of production is still regarded as a main factor for selecting harvesting systems in the planning phase and for the evaluation of their efficiency. Rapid development of the renewable energy sector and bioenergy sector as its key part raised a question of bioenergy competitiveness when compared to energy produced from fossil fuels as well as from other renewables. At this point, when timber harvesting systems had to be analysed as energy production systems, unit of a timber product could no longer be the sole denominator for calculating the efficiency and novel research methods had to be applied. In this research, energy efficiency of mechanized timber harvesting by a harvester (Timberjack 1470D) – forwarder (Timberjack 1710D) system in an 80-year old broadleaf harvesting site was determined, and expressed as EROI (Energy Return On Investment). Field experiment consisted of time studies and measuring fuel consumption while other input data was gathered from own previous research in similar conditions or literature sources. System boundaries were set at the landing, i.e. roundwood delivered to the roadside is regarded as a system’s final product. Energy investment was calculated on PMH (Productive Machine Hour) level enabling the use of input parameters of cost calculations as well as expressing the results in the span of main factors (DBH and extraction distance) used in the productivity models. Energy investment of a harvester amounted to 1022.4 MJ/PMH (84% fuel ; 9% production of a machine ; 6% oil ; 1% tyres) and that of a forwarder to 529.9 MJ/PMH (75% fuel ; 16% production of a machine ; 5% oil ; 4% tyres). When expressed on a product level, energy investment of a harvesting system reached 130 MJ/m3 (for average DBH = 23 cm and average extraction distance of 360 m). Energy return for beech and hornbeam wood in fresh state (45% moisture content) is 9282 MJ/m3, thus the application of the investigated harvesting system under the conditions of the specified felling site results with EROI of 71.5. Furthermore, EROI is expected to range from 38 (for DBH 12.5 cm) to 102 (for DBH 42.5 cm) with the average extraction distance of 360 m ; and from 76 (for 100 m extraction distance) to 65 (for 800 m extraction distance) with the average DBH of 23 cm. Reduction of the moisture content to half of the initial value (by natural drying of energy wood) would increase the energy gain by 8%. But, in order to cover the EROI of the final energy product, system boundaries should be shifted to the end user. Energy investment calculation should cover the transportation and preferably explore different transformation processes (production of firewood in the household ; mechanized production of oven-ready chopped firewood and production of wood pellets).

Izvorni jezik
Engleski

Znanstvena područja
Šumarstvo

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