- Email: [email protected]
Techniques for the transportation of complete-trees from the termination of Peach Orchards
Biomass and Bioenergy 130 (2019) 105378
Contents lists available at ScienceDirect
Biomass and Bioenergy journal homepage: www.elsevier.com/locate/biombioe
Research paper
Techniques for the transportation of complete-trees from the termination of Peach Orchards
T
Alberto Assirellia,∗, Enrico Santangeloa, Massimo Brambillab, Carlo Bisagliab, Vincenzo Civitaresea, Giuseppina Caraccioloc, Raffaele Spinellid a
Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria, Centro di Ingegneria e Trasformazioni agroalimentari (CREA-IT), Via della pascolare 16, 00015, Monterotondo, Rome, Italy b Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria, Centro di Ingegneria e Trasformazioni agroalimentari (CREA-IT), Via Milano 43, 24047, Treviglio, Bergamo, Italy c Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria, Centro di Olivicoltura, Frutticoltura e Agrumicoltura (CREA-OFA), Via la Canapona 1bis, Forlì, Forlì Cesena, 47121, Italy d CNR-IBE, Via Madonna del Piano 10, I-50019, Sesto Fiorentino, Firenze, Italy
A R T I C LE I N FO
A B S T R A C T
Keywords: Crop termination Chipping Grinding Compaction Roots
The termination of a fruit orchard generates a considerable amount of residues that can be used as fuel in biomass-fired power plants. Various studies have explored the separate collection of the above-ground tree portion and the rootstock. The present work analyses the potential of complete-tree harvesting (aboveground biomass and rootstock) from a depleted peach orchard and compares this technique with the collection of the aboveground biomass (pruning residues and stems) only. Complete trees were extracted and piled, then ground into chunks and cleaned to reduce contamination with dirt and stones. As an alternative, trees were cut, stacked and chipped, leaving the rootstocks in the ground for later disposal. Extracting complete trees and piling them at the field's edge proceeded at a pace of ca. 1 ha day−1. Grinding and cleaning allowed reducing soil contamination by 10–15%. The study showed that complete-tree harvesting is a viable approach to containing the costs of biomass recovery from depleted orchards. Supply chain efficiency is maximized by including biomass compaction during the loading of trucks.
1. Introduction Regardless of crop type, the termination of permanent crops yields significant volumes of wood biomass, which can be exploited as a renewable fuel in bioenergy plants along with the periodic prunings on which an important research activity was carried out [1–4]. The average duration of the fruit plants is progressively reducing not only for physiological reasons but also following the changing demand of the market. As a result, the amount of biomass available from the termination of orchards is expected to increase in the near future [5]. Currently, the most common solutions to manage the biomass from terminated orchards is mulching/shredding with subsequent removal and burning, which results into a significant disposal cost [6]. Therefore, it may be interesting to devise a cost-effective system for managing the biomass obtained from the termination of orchards [7–10]. The handling of whole trees (aboveground biomass and stump) at the time of termination is an interesting new approach to recover all the
∗
available biomass in one single pass, thus simplifying the operation and possibly increasing operational efficiency. Usually, the complete termination of an orchard requires at least two passes: with the first pass, the above-ground tree portion is cut and removed, while in the second pass the rootstock is pulled out, cleaned and disposed of. Rootstock disposal after orchard termination is a very challenging task, and the same techniques used for forest crops [11,] have also been applied to fruit orchards [12,13]. Rootstock extraction, cleaning and collection requires the use of an excavator or of other special machines [7], and raises the critical issue of contamination, since ground particles stick to the roots and detract from biomass quality, decreasing its market value [14–17]. Dedicated root-extraction equipment is also design to perform a first rough cleaning, but the effect depends in a large measure from soil texture and working conditions, leading to a large variability in the results [18,19]. Harvesting complete trees (above-ground portion plus rootstock) of depleted orchards in one single pass seems an interesting alternative. In
Corresponding author. E-mail address: [email protected] (A. Assirelli).
https://doi.org/10.1016/j.biombioe.2019.105378 Received 9 April 2019; Received in revised form 6 August 2019; Accepted 18 September 2019 Available online 24 September 2019 0961-9534/ © 2019 Elsevier Ltd. All rights reserved.
Biomass and Bioenergy 130 (2019) 105378
A. Assirelli, et al.
2. Materials and methods
Italy, experiences on depleted plantation are rather limited and have been carried out with different types of mechanization, but never in one single pass. Most commonly, two separate units are used, one for felling (by a hydraulic shear on the front lift of the tractor) and windrowing the trees and the other for chipping (a drum type chipper) accompanied by a tractor and a trailer unit (shuttles), for hauling the wood chips to a roadside landing or directly to the end user [7]. Past studies have demonstrated the flexibility of this system that allowed a cost-effective collection also in small fields (smaller than 1 ha). Otherwise, plants are cut with a chainsaw, loaded on a trailer and piled at the field's edge, and finally chipped and transported to the power plant [20]. Depending on mechanization level, production cost varied from 30 to almost 100 € t−1 of fresh chips, delivered to the power station [7,20]. This still left the rootstocks behind, which could be recovered with an excavator or a dedicated rootstock harvester [18], piled at the field's edge and finally ground with a dedicated shredder [21]. The present study was conducted on a peach (Prunus persica (L.) Batsch) orchard. Peach orchards represent one of the most important permanent crops in Italy: in 2018, the area planted with peach orchards exceeded 66,000 ha [22]. As a matter of fact, peach is the second permanent crop for importance in Italy, after citrus crops [22]. Moreover peach orchards may yield around 2.5–3 t ha−1 of pruned wood biomass, corresponding to hundred tons of feedstock potentially available annually by the renewal cycle. The amount may be higher in the intensive plantation (1000 plants ha−1) increasingly common across Italy [5]. While the comparison of different biomass recovery techniques has led to interesting results [23], the recovery of complete trees from orchards is still unexplored. Therefore, the goal of this study was to carry out a preliminary analysis of the whole collection chain including transportation (Fig. 1). The analysis took the harvesting of aboveground biomass as the control and was conducted for three transportation modes (loose biomass, compacted biomass and comminuted biomass).
2.1. The site The study took place in San Bartolo, Ravenna, Italy (44°21′30.77″N 12°11′50.54″ E) in Northern Italy. The plantation was a peach orchard established at a 6 × 3.5 m spacing, and grown according to the “Italian delayed vase” system. The orchard was 14 years-old at the end of the cycle. The total surface area covered by the experiment was 0.90 ha. 2.2. Collection Two systems were studied. The first concerned the collection of the aboveground biomass only, without the rootstocks (left on the ground for later handling). The second focused on the extraction and management of complete trees (aboveground biomass plus rootstocks). In both cases, trees were collected and piled at the field's edge, and then moved to a central yard within the farm. This was done using either a truck-trailer unit with 55 m3 load capacity (Scania 420) or a semitrailer with 90 m3 capacity (Iveco Stralis). Both machines were equipped with a loader and would operate independently. Once loaded on the truck, the biomass was left loose or compacted. In the latter case, a large log weighing 450 kg was grabbed with the crane and used to partially break and compact the loaded biomass (Fig. 2). Compaction was accomplished in two steps: when the container was half full, and then when it was completely full. Every single truck and trailer transporting the biomass (compacted or loose) was weighed on a certified weighbridge, before and after loading. Productivity data for extraction, piling, and loading were collected according to the CIOSTA (Comité International d’Organisation Scientifique du Travail en Agriculture) methodology and to the recommendations of the Italian Society of Agricultural Engineering (A.I.I.A.) 3A R1 [24]. Previous research had shown how the type and form of woody
Fig. 1. Schematic representation of the two supply chains. The boxes with the continuous black line represent the phases analyzed in the present study. Grey arrows: aboveground biomass. Black arrows: whole tree. 2
Biomass and Bioenergy 130 (2019) 105378
A. Assirelli, et al.
Fig. 2. Compaction phase during the loading of the whole trees.
consumption was measured during the test by starting with a full tank at the beginning of the trail and then refilling the tank (in the same level position) at the end of the work. Fuel price was assessed at 0.89 € l−1, [26]. The cost of subcontracting for extraction and windrowing (only extraction 67 € h-1, total agreed between the operators 75€ h-1) and piling (tracks tractor with dozer blade until 58.67 kW, total agreed between the operators 50 € h-1) work were obtained from the current tariff tables agreed by the regional farm contractors union [27]. Data processing was carried out with the PAST software. Statistical analysis consisted of extracting descriptive statistics and then checking the significance of any differences between treatments through the oneway ANOVA test, after checking the dataset for compliance with the homoscedasticity and normality assumptions. Post hoc comparisons were conducted using Tukey's HSD test.
biomass can be influence the chipper performances [25], so we also are oriented to evaluate other grinding systems. At the central yard, rootless trees were chipped, while complete trees were ground with a robust hammer mill and cleaned, to remove soil and other contaminants sticking to the rootstocks. Usually, biomass fuel derived from rootless trees does not present any challenges for the combustion plants, while biomass fuel produced from complete trees requires cleaning to reduce ash content below 10%. If this threshold is exceeded, the buyers apply penalties on the final payments. Both biomass fuel types were loaded on roll-on/roll-off containers and hauled to the power plant with truckand-trailer rigs. A tracked excavator (Hyundai 140LCD7), a mobile chipper (Pezzolato 1000/1000), a heavy shredder (Doppstadt DW 30/ 60) and the rotary sieve (Farwick Mustang) were used for comminution and cleaning. The bulk density of the ground comminuted biomass was calculated in compliance with the standard UNI EN 15103:2010, while as far as the means of transport are concerned, the density has always been obtained from the ratio between transported weight and volumetry. Random samples were collected before and after cleaning in the rotary sieve and analyzed for the presence of soil contaminants. At the same time, contamination before sieving was estimated by determining the mass getting into the sieve, as well as the mass of the two main piles produced by the sieve, and namely: the clean chip pile and the contaminants pile. During hauling, the average speed of three trips was recorded for each of the 4 hauling treatment (articulated truck or truck-trailer, transporting compacted or loose feedstock). Overall, the vehicles travelled on 39 unpaved roads, 85 ordinary roads, and passed through 48 inhabited centers. Where available the drivers recorded fuel consumptions using their on-board fuel meters. The total cost of the mechanical intervention was calculated on the basis of working capacity (h ha-1, measured) and the listed prices of personnel, fuel and subcontracting services In particular, personnel cost was set at 15€ hour−1. Without on-board fuel meter the fuel
3. Results and discussion 3.1. Extraction and piling To our knowledge, the topic of the present work is rather specific because no other work about complete-tree harvesting of terminated orchards can be found in the recent bibliography. So far, all works about complete-tree harvesting come from the forest sectors, and the most recent one is over 10 years old [28]. Similarly, few works deal with the recovery of aboveground wood from depleted orchards [7,20], while many others tackled rootstock removal after termination [11,19]. In this way, the comparison of our results with similar studies remains difficult. The productivity of extraction and piling of complete trees at the field's edge (Fig. 3) was about 0.5 ha day−1. Complete tree extraction was the most time-consuming task requiring 13.1 h ha−1, while piling needed just 2.2 h ha−1 (Table 1). As a result, tree extraction accounted for the 88% of the cost per hectare. Though hardly comparable, the data are lower than those required to cut, harvest and pile the aboveground
Fig. 3. Compacted biomass stored in the field. 3
Biomass and Bioenergy 130 (2019) 105378
A. Assirelli, et al.
Table 1 Productivity and main costs of extraction and piling of the whole tree.
−1
Working capacity (h ha ) Machine cost (A) € h−1(a) € ha−1 Fuel (B) € l−1(b) Hourly consumption (l h−1) € ha−1 Personnel (C) € h−1(c) € ha−1 Total (A + B + C) € ha−1
Extraction
Piling
13.1
2.2
75.0 982.5
50.0 110.0
0.89 20.0 233.2
0.89 28.0 54.8
15.0 196.5
15.0 33.0
1,412.2
197.8
Fig. 4. Loading time (mean ± SD) for the truck or the articulated truck in the field. Different letters indicate a difference for P ≤ 0.0001 according to Tukey's HSD test.
Notes. a Source [27]. b Source [26]. c Labour cost = 15 € hour−1 = hour worksite time, including delays.
(43 vs 32 min for the truck-trailer combination and 22 vs 15 min for the articulated truck). However, compaction allowed a significant increase of payload, which likely offset the additional time consumption. The additional time required for compaction was lower for the truck-trailer combination (11 min) than for the articulated truck (13 min). Loading time was shorter for the truck compared with the trucktrailer combination, both when compacting the load (0.36 vs 0.47 min m−3) and when leaving it uncompacted (0.28 vs 0.40 min m−3) (Fig. 4). The loading time of the loose material in the truck-trailer combination was comparable with that of the compacted biomass in the truck (0.36 vs 0.40 min m−3). Although in the trucktrailer combination the vehicles to load were two, the simplified loading (loose) allowed to reduce the average time per loaded volume. Such a result must be kept into account in defining the most cost-effective supply chain. Hauling time was unaffected by biomass compaction (Fig. 5), but it was dependent on truck type (with or without trailer). After compaction, the payload of the truck-trailer, the most common logistic transport system increased by 26.1% compared to the uncompacted treatment, exceeding in some cases 11 t, corresponding to a bulk density of 196 kg m−3. However, the weight of the load and vehicle manoeuvrability affected the speed maintained during transportation. On the road network used for the trips, within the same kind of vehicle, a different type of compaction showed the same transport times and hourly costs. Transport time was not affected by the compaction of the biomass (Fig. 5), but mainly depended on the type of truck (with trailer or articulated) and therefore also on its maneuverability. After compaction, the payload of the truck is increased by 21% compared to the uncompacted biomass for the same vehicle, exceeding in this case the 20 t load capacity with the same volume. However, the weight of the load and the maneuverability of the vehicle affected the speeds
biomass of a kiwi orchard as reported by Ref. [20] which overall needed about 20 h ha−1. In our study, compaction of piles allowed increasing the performance of the logistic chain and facilitated unloading of the biomass at the central yard. Complete trees needed cleaning from soil particles. The presence of contaminants (soil and stones) in wood fuel is a problem both on the pruning collection [3] and to an even greater extent for rootstock recovery [19]. Inorganic contaminants determine an increase of ash content and a decrease of calorific value: for that reason, highly contaminated fuel loads are often rejected on arrival at the plant gates [18,19]. Pear rootstocks may contain 54–75% in weight of soil soon after the extraction [18]. In a work on vineyard stumps [19], soil contamination decreased from 6.6-8.9% to 4.3–5.1% after six months of storage, depending on the rootstock type. To reduce contamination, complete trees were passed through a shredder and a rotary sieve. Although not validated statistically, the system tested in the present study gave positive results regarding the amount of soil removal and, hence, the overall decrease of soil particle pollution. Samples collected before cleaning contained until 18–20% of soil particles, while samples collected after cleaning only contained from 5 to 7%. Such values are comparable with those reported by Ref. [19] for vineyard rootstocks, although here they refer to the complete tree in our study, cleaning recorded the same productivity as shredding, so that the two tasks were part of one same sequence. However, cleaning required additional equipment and personnel and determined an increase of biomass processing cost. The experiment demonstrates the successful application of industrial machines borrowed from the earthmoving and demolition sectors [7]. Rootless tree elements were comminuted with a forestry chipper and the final product was deemed ready for direct delivery to the biomass power plant without any need for additional processing. In both cases there was the need to set up a separate area inside the farm to optimize the efficiency of the machines.
3.2. Loading and hauling Transport of loose or compacted complete tree biomass could influence the reduction of soil particle pollution of the biofuel following the partial breakage resulting from rootstock compaction. In the open field, biomass compaction had a significant influence also on loading time. On average, loading a truck-trailer combination took longer than loading a articulated truck, although the truck-trailer combination present a smaller volume capacity (55 m3 vs 90 m3). In both cases, biomass compaction resulted in an increase of loading time
Fig. 5. Total time of hauling of loose and compacted feedstock from the field to the farm centre. Different letters indicate a difference for P ≤ 0.001 according to Tukey's HSD test. 4
Biomass and Bioenergy 130 (2019) 105378
A. Assirelli, et al.
present work, Pezzolato PTH 900/660 in Ref. [20] and a conventional drum type developed for forestry in Ref. [7]. The shredder operated a rough comminution (pre-grounding) of the complete plants and the product was then processed by a rotary sieve which removed much of the contaminants. The combination of these two machines showed a working capacity of 33.3 t h−1 and an overall hourly consumption of 40 l h−1: 31 l h−1 consumed by the shredder and 9 l h−1 byrotary sieve. This additional step increased the fuel consumption and hence the structure of the cost. On the other hand, the use of the rotary sieve reduced contamination and substantially improved the quality of the final product. In this case the effect has a particular value because, as discussed above, complete trees with the roots attached contain a greater amount of soil that must be removed. The wood biomass obtained following chipping (wood chips) or the pre-treatment (shredding) were transferred to the energy plant using the same transport logistics (truck-trailer and/or articulated truck). An exception may be the case when the pre-ground material was reprocessed to produce wood chips for specific needs. The present study represents the first case of application of preground having a cleaning function, previously limited to wood chips [3].
Fig. 6. Amount of hauled biomass (t) with different degrees of comminution.
maintained during transport, especially due to the curves and the times of restart from the intersections. However, these differences did not show significant values given the average loads considerably lower than the potential of the vehicles. From the data collected on the route used for the trips, for the same vehicle, both the compacted and the loose load showed the same transport times and hourly cost, reducing the hourly transport cost (€ t−1) for a greater load capacity. During the surveys, the transport of different biomass treatments (complete-tree, pre-ground and wood chips) was monitored on ordinary working conditions. Each load had a different density which, in turn, led to a variable capacity for biomass delivery (Fig. 6). In all cases, the payload of the semitrailer was higher than that of the road train, thanks to its greater volume capacity. When biomass was transported in the form of wood chips, the payload was higher compared with pre-ground biomass, due to its coarser texture and resulting lower bulk density. In particular, mean payload decreased from 27.5 t to 25.0 t for the semitrailer. The transport of complete trees resulted in a much lower payload: 10.4 t for the truck and 16.1 for the semitrailer. Pre-grounding proved to be an interesting solution, as it allowed increasing payload to 18.6 t on the road train and to 25.03 t on the semitrailer - values that are not too far from those obtained with wood chips. The different mode of comminution affected also the bulk density of the feedstock: for the whole non-compacted plants the bulk density was 155 kg m−3 that almost doubled for the wood chips (305 kg m−3).
4. Conclusion In the present work, the recovery of complete trees from orchards at termination was studied and an optimized collection chain was analyzed. The collection of complete trees in a single pass appears as a promising technique to reduce delivered cost. However, unlike the rootless trees that are directly chipped, the proposed system included an additional step in which the complete trees were pre-grounded and cleaned. This passage allowed to abate the contamination from 18-20% to 5–7%, well below the threshold of acceptability by most power plants For shredding and cleaning, it was necessary to identify a dedicated area within the farm in order to allow an efficient processing of the biomass, to reduce the permanence in the field, to limit the cost and the environmental impact. Finally, the compaction of the biomass inside the truck brought positive results in terms of transport cost and cleaning efficiency. The step of pre-grounding allowed to attain a payload (18.6 t on the road train and to 25.03 t on the articulated vehicle) comparable with the complete comminution in wood chips. As a result, the advantages in relation to the distances to be covered can make this collection and delivery system even more effective. The work represents just a preliminary experience, which should be repeated on a range of different environmental, agronomic and logistical conditions. However, to our knowledge, th is the only available experience of complete-tree harvesting in terminated orchards. In fact, this early experience has encouraged some companies to design and implement different collection systems for a better exploitation of biomass.
3.3. Chipping, pre-grounded and cleaning Once harvested and loaded, complete trees were moved to the farm centre and then followed two different paths (Fig. 1): plants without a rootstock were directly chipped with a wood chipper, while plants complete with rootstocks were treated with a shredder and a rotary sieve. In the present study, the wood chipper showed an operational capacity of 22 t h−1 and an hourly fuel consumption of 42 l h−1. Productivity was within the range (15–30 t h−1) reported by Spinelli (2011) for the recovery of forest residues [29]. The same author showed that chipping performed at the field's edge on non-industrial short-rotation forestry of poplar might vary from 28 to 34 t h−1 [30]. However, most of the data on chipping performance are available for forest residues for which a huge bibliography exists. A possible comparison may be made with [7] where the chipping of peach, apple and plum trees (without roots) with a self-feeding chipper or a drum chipper fed by a separate loader required a total work time of 439 and 251 s t−1 respectively, corresponding to 8 and 14 t h−1. The performance of the wood chipper used in our study was higher than [7], but the hourly fuel consumption reported by Ref. [7] was 40.5% lower (25 l h−1). The productivity observed by Ref. [20] on the removal of kiwi plantation was even lower. With a production of 20.6 tDM ha−1 and a chipper productivity of 0.21 ha h−1, productivity was in fact 4.3 t h−1. The different feedstock types and chipper models used in these studies may account for the observed differences: Pezzolato 1000/1000 in the
5. Notes Reference to specific makes and models is solely made to help readers to assess the study correctly, and it does not involve any endorsement of specific makes and models to the exclusion of similar machines produced by other manufacturers. Acknowledgements This work was supported by theItalian Ministry of Agriculture (MiPAAFT) under the AGROENER project (D.D. n. 26329, 1 april 2016) - http://agroener.crea.gov.it/. The authors would like to thank the Enerlegno ltd of Casemurate (Ra) Italy, bioenergy company operates in the forestry and agricultural sector for the production of woody biomasses destined to the energy purpose for his technical support in equipment and field availability. 5
Biomass and Bioenergy 130 (2019) 105378
A. Assirelli, et al.
References
[16] M.A. Mendìvil, P. Munoz, M.P. Morales, M.C. Juàrez, E. Garcia-Escudero, Chemical Characterization of pruned vine shoots from La Rioja (Spain) for obtaining solid bio-fuels, J. Renew. Sustain. Energy 5 (3) (2013). [17] W. Cichy, M. Witczak, M. Walkowiak, Fuel properties of woody biomass from pruning operations in fruit orchards, Bioresour. 12 (3) (2017) 6458–6470. [18] G. Picchi, L. Pari, A. Scarfone, M. Barontini, R. Spinelli, Unearthing the hidden resource: biomass from rootstock recovery, Biofuels, Bioprod. Biorefining 6 (2016) 246–256, https://doi.org/10.1002/bbb.1643. [19] L. Pari, A. Scarfone, V. Alfano, S. Bergonzoli, F. Gallucci, E. Santangelo, Testing open-air storage of stumps to provide clean biomass for energy production, Energies 10 (2017) 1725, https://doi.org/10.3390/en10111725. [20] M. Manzone, F. Gioelli, P. Balsari, Kiwi clear-cut: first evaluation of recovered biomass for energy production, Energies 10 (2017) 1837, https://doi.org/10.3390/ en10111837. [21] R. Spinelli, G. Aminti, F. De Francesco, N. Magagnotti, L. Pari, Test of a new mobile machine for comminuting and cleaning rootstock waste, Biofuels, Bioprod. Biorefining 12 (2018) 949–957, https://doi.org/10.1002/bbb.1896. [22] ISTAT (Istituto Nazionale di Statistica), Principali coltivazioni legnose agrarie, Available online: https://www.istat.it/it/archivio/124365 , Accessed date: 29 March 2018. [23] M. Strandgard, P. Turner, L. Mirowski, M. Acune, Potential application of overseas forest biomass supply chain experience to reduce costs in emerging Australian forest biomass supply chains, a literature review, Aust. For. 82 (1) (2019) 9–17 https:// doi.org/10.1080/00049158.2018.1555907. [24] L. Bodria, G. Pellizzi, P. Piccarolo, Meccanica Agraria vol II: la meccanizzazione, Edizioni Il Sole 24ORE, Bologna, Italy, 2006. [25] A. Assirelli, V. Civitarese, R. Fanigliulo, L. Pari, D. Pochi, E. Santangelo, R. Spinelli, Effect of piece size and tree part on chipper performance, Biomass Bioenergy 54 (2013) 77–82. [26] Camera di Commercio Agricoltura, Industria e Artigianato Provincia Forlì Cesena, Nota Informativa sui Prezzi dei Carburanti, 30/09/2018. Available online: https:// www.romagna.camcom.it/download/regolazione-del-mercato/prezzi/listinoprodotti-petroliferi/-listino-prodotti-petroliferi-del-30-09-2018/-listino-prodottipetroliferi-del-30-09-2018.pdf?DWN=4946(accessed on 26 November 2018). [27] APIMAI, Associazione Provinciale Imprese di Meccanizzazione Agricola e Industriale, Tariffario 2018 per le Provincia di Forlì-Cesena e Rimini, 2018 Available online: http://www.caiagromec.it/sites/unima.it/files/tariffari/apima_ libretto_2018_8.pdf , Accessed date: 4 December 2018. [28] R. Spinelli, N. Magagnotti, G. Picchi, Complete tree harvesting as an alternative to mulching in early thinnings, For. Prod. J. 59 (2009) 79–84. [29] R. Spinelli, Supply of wood biomass for energy purpose: global trends and perspectives, In: Proceedings of the 22nd Annual Meeting of the Club of Bologna, November, 13-14. [30] R. Spinelli, J. Schweier, F. De Francesco, Harvesting techniques for non-industrial biomass plantations, Biosyst. Eng. 113 (4) (2012) 319–324.
[1] L. Pari, A. Suardi, E. Santangelo, D. García-galindo, A. Scarfone, V. Alfano, Current and innovative technologies for pruning harvesting: a review, Biomass Bioenergy 107 (2017) 398–410, https://doi.org/10.1016/j.biombioe.2017.09.014. [2] R. Spinelli, N. Magagnotti, C. Nati, Harvesting vineyard pruning residues for energy use, Biosyst. Eng. 105 (2010) 316–322, https://doi.org/10.1016/j.biosystemseng. 2009.11.011. [3] A. Acampora, S. Croce, A. Assirelli, A. Del Giudice, R. Spinelli, A. Suardi, L. Pari, Product contamination and harvesting losses from mechanized recovery of olive tree pruning residues for energy use, Renew. Energy 53 (2013) 350–353, https:// doi.org/10.1016/j.renene.2012.12.009. [4] N. Bilandzija, N. Voca, T. Kricka, A. Matin, V. Jurisic, Energy potential of fruit tree pruned biomass in Croatia, Span. J. Agric. Res. 10 (2) (2017) 292–298. [5] D. Garcìa-Galindo, M. Gòmez-Palmero, P. E, S. Germer, L. Pari, V. Alfano, A. Dyjakon, J. Sagarna, S. Rivera, C. Poutrin, Agricultural pruning as biomass resource: generation, potentials and current fates. An approach to its state in Europe, 24th Eur. Biomass Conf. Exhib. 6-9 June 2016, 2016, pp. 1579–1595. Amsterdam. [6] A. Dyjakon, J. Boer, P. Bukowski, F. Adamczyk, P. Frackowiak, Wooden Biomass potential from apple orchards in Poland, Drewno 59 (198) (2016) 73–86. [7] G. Picchi, L. Pari, G. Aminti, R. Spinelli, Cost-effective biomass supply from orchard termination with highly-mobile low-investment equipment, Biomass Bioenergy 94 (2016) 78–84. [8] G. Picchi, G. Aminti, R. Spinelli, Dai frutteti cippato “competitivo” rispetto ai valori di mercato, Terra Vita 4 (2014) 46. [9] V. Civitarese, S. Faugno, R. Picchio, A. Assirelli, G. Sperandio, L. Saulino, M. Crimaldi, Production of selected short-rotation wood crop species and quality of obtained biomass, Eur. J. For. Res. 137 (4) (2018) 541–552. [10] S. Faugno, V. Civitarese, A. Assirelli, G. Sperandio, L. Saulino, M. Crimaldi, M. Sannino, Chip quality as a function of harvesting methodology, Chem. Eng. Trans. 58 (2017) 271–276. [11] J. Laitila, Y. Nuutinen, Efficiency of integrated grinding and screening of stump wood for fuel at roadside landing with a low-speed double-shaft grinder and a star screen, Croat. J. Eng. 36 (2015) 19–32. [12] R. Picchio, S. Verani, G. Sperandio, R. Spina, E. Marchi, Stump grinding on a poplar plantation: working time, productivity, and economic and energetic inputs, Ecol. Eng. 40 (2012) 117–120, https://doi.org/10.1016/j.ecoleng.2011.11.012. [13] R. Spinelli, C. Nati, N. Magagnotti, Harvesting and transportation of root biomass from fast-growing poplar plantations, Silva Fenn. 39 (4) (2005) 539–548. [14] D. Duca, G. Toscano, A. Pizzi, G. Rossini, S. Fabrizi, G. Lucesoli, A. Servili, V. Mancini, G. Romanazzi, Ch Mengarelli, Evaluation of the characteristics of vineyards pruning residues for energy applications: effect of different copper-based treatments, J. Agric. Eng. 47 (1) (2016) 22–27. [15] J. Werkelin, B.J. Skrifvars, M. Zevenhoven, B. Holmbom, M. Hupa, Chemical forms of ash-forming elements in woody biomass fuels, Fuel 89 (2010) 481–493, https:// doi.org/10.1016/j.fuel.2009.09.005.
6
Contents lists available at ScienceDirect
Biomass and Bioenergy journal homepage: www.elsevier.com/locate/biombioe
Research paper
Techniques for the transportation of complete-trees from the termination of Peach Orchards
T
Alberto Assirellia,∗, Enrico Santangeloa, Massimo Brambillab, Carlo Bisagliab, Vincenzo Civitaresea, Giuseppina Caraccioloc, Raffaele Spinellid a
Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria, Centro di Ingegneria e Trasformazioni agroalimentari (CREA-IT), Via della pascolare 16, 00015, Monterotondo, Rome, Italy b Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria, Centro di Ingegneria e Trasformazioni agroalimentari (CREA-IT), Via Milano 43, 24047, Treviglio, Bergamo, Italy c Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria, Centro di Olivicoltura, Frutticoltura e Agrumicoltura (CREA-OFA), Via la Canapona 1bis, Forlì, Forlì Cesena, 47121, Italy d CNR-IBE, Via Madonna del Piano 10, I-50019, Sesto Fiorentino, Firenze, Italy
A R T I C LE I N FO
A B S T R A C T
Keywords: Crop termination Chipping Grinding Compaction Roots
The termination of a fruit orchard generates a considerable amount of residues that can be used as fuel in biomass-fired power plants. Various studies have explored the separate collection of the above-ground tree portion and the rootstock. The present work analyses the potential of complete-tree harvesting (aboveground biomass and rootstock) from a depleted peach orchard and compares this technique with the collection of the aboveground biomass (pruning residues and stems) only. Complete trees were extracted and piled, then ground into chunks and cleaned to reduce contamination with dirt and stones. As an alternative, trees were cut, stacked and chipped, leaving the rootstocks in the ground for later disposal. Extracting complete trees and piling them at the field's edge proceeded at a pace of ca. 1 ha day−1. Grinding and cleaning allowed reducing soil contamination by 10–15%. The study showed that complete-tree harvesting is a viable approach to containing the costs of biomass recovery from depleted orchards. Supply chain efficiency is maximized by including biomass compaction during the loading of trucks.
1. Introduction Regardless of crop type, the termination of permanent crops yields significant volumes of wood biomass, which can be exploited as a renewable fuel in bioenergy plants along with the periodic prunings on which an important research activity was carried out [1–4]. The average duration of the fruit plants is progressively reducing not only for physiological reasons but also following the changing demand of the market. As a result, the amount of biomass available from the termination of orchards is expected to increase in the near future [5]. Currently, the most common solutions to manage the biomass from terminated orchards is mulching/shredding with subsequent removal and burning, which results into a significant disposal cost [6]. Therefore, it may be interesting to devise a cost-effective system for managing the biomass obtained from the termination of orchards [7–10]. The handling of whole trees (aboveground biomass and stump) at the time of termination is an interesting new approach to recover all the
∗
available biomass in one single pass, thus simplifying the operation and possibly increasing operational efficiency. Usually, the complete termination of an orchard requires at least two passes: with the first pass, the above-ground tree portion is cut and removed, while in the second pass the rootstock is pulled out, cleaned and disposed of. Rootstock disposal after orchard termination is a very challenging task, and the same techniques used for forest crops [11,] have also been applied to fruit orchards [12,13]. Rootstock extraction, cleaning and collection requires the use of an excavator or of other special machines [7], and raises the critical issue of contamination, since ground particles stick to the roots and detract from biomass quality, decreasing its market value [14–17]. Dedicated root-extraction equipment is also design to perform a first rough cleaning, but the effect depends in a large measure from soil texture and working conditions, leading to a large variability in the results [18,19]. Harvesting complete trees (above-ground portion plus rootstock) of depleted orchards in one single pass seems an interesting alternative. In
Corresponding author. E-mail address: [email protected] (A. Assirelli).
https://doi.org/10.1016/j.biombioe.2019.105378 Received 9 April 2019; Received in revised form 6 August 2019; Accepted 18 September 2019 Available online 24 September 2019 0961-9534/ © 2019 Elsevier Ltd. All rights reserved.
Biomass and Bioenergy 130 (2019) 105378
A. Assirelli, et al.
2. Materials and methods
Italy, experiences on depleted plantation are rather limited and have been carried out with different types of mechanization, but never in one single pass. Most commonly, two separate units are used, one for felling (by a hydraulic shear on the front lift of the tractor) and windrowing the trees and the other for chipping (a drum type chipper) accompanied by a tractor and a trailer unit (shuttles), for hauling the wood chips to a roadside landing or directly to the end user [7]. Past studies have demonstrated the flexibility of this system that allowed a cost-effective collection also in small fields (smaller than 1 ha). Otherwise, plants are cut with a chainsaw, loaded on a trailer and piled at the field's edge, and finally chipped and transported to the power plant [20]. Depending on mechanization level, production cost varied from 30 to almost 100 € t−1 of fresh chips, delivered to the power station [7,20]. This still left the rootstocks behind, which could be recovered with an excavator or a dedicated rootstock harvester [18], piled at the field's edge and finally ground with a dedicated shredder [21]. The present study was conducted on a peach (Prunus persica (L.) Batsch) orchard. Peach orchards represent one of the most important permanent crops in Italy: in 2018, the area planted with peach orchards exceeded 66,000 ha [22]. As a matter of fact, peach is the second permanent crop for importance in Italy, after citrus crops [22]. Moreover peach orchards may yield around 2.5–3 t ha−1 of pruned wood biomass, corresponding to hundred tons of feedstock potentially available annually by the renewal cycle. The amount may be higher in the intensive plantation (1000 plants ha−1) increasingly common across Italy [5]. While the comparison of different biomass recovery techniques has led to interesting results [23], the recovery of complete trees from orchards is still unexplored. Therefore, the goal of this study was to carry out a preliminary analysis of the whole collection chain including transportation (Fig. 1). The analysis took the harvesting of aboveground biomass as the control and was conducted for three transportation modes (loose biomass, compacted biomass and comminuted biomass).
2.1. The site The study took place in San Bartolo, Ravenna, Italy (44°21′30.77″N 12°11′50.54″ E) in Northern Italy. The plantation was a peach orchard established at a 6 × 3.5 m spacing, and grown according to the “Italian delayed vase” system. The orchard was 14 years-old at the end of the cycle. The total surface area covered by the experiment was 0.90 ha. 2.2. Collection Two systems were studied. The first concerned the collection of the aboveground biomass only, without the rootstocks (left on the ground for later handling). The second focused on the extraction and management of complete trees (aboveground biomass plus rootstocks). In both cases, trees were collected and piled at the field's edge, and then moved to a central yard within the farm. This was done using either a truck-trailer unit with 55 m3 load capacity (Scania 420) or a semitrailer with 90 m3 capacity (Iveco Stralis). Both machines were equipped with a loader and would operate independently. Once loaded on the truck, the biomass was left loose or compacted. In the latter case, a large log weighing 450 kg was grabbed with the crane and used to partially break and compact the loaded biomass (Fig. 2). Compaction was accomplished in two steps: when the container was half full, and then when it was completely full. Every single truck and trailer transporting the biomass (compacted or loose) was weighed on a certified weighbridge, before and after loading. Productivity data for extraction, piling, and loading were collected according to the CIOSTA (Comité International d’Organisation Scientifique du Travail en Agriculture) methodology and to the recommendations of the Italian Society of Agricultural Engineering (A.I.I.A.) 3A R1 [24]. Previous research had shown how the type and form of woody
Fig. 1. Schematic representation of the two supply chains. The boxes with the continuous black line represent the phases analyzed in the present study. Grey arrows: aboveground biomass. Black arrows: whole tree. 2
Biomass and Bioenergy 130 (2019) 105378
A. Assirelli, et al.
Fig. 2. Compaction phase during the loading of the whole trees.
consumption was measured during the test by starting with a full tank at the beginning of the trail and then refilling the tank (in the same level position) at the end of the work. Fuel price was assessed at 0.89 € l−1, [26]. The cost of subcontracting for extraction and windrowing (only extraction 67 € h-1, total agreed between the operators 75€ h-1) and piling (tracks tractor with dozer blade until 58.67 kW, total agreed between the operators 50 € h-1) work were obtained from the current tariff tables agreed by the regional farm contractors union [27]. Data processing was carried out with the PAST software. Statistical analysis consisted of extracting descriptive statistics and then checking the significance of any differences between treatments through the oneway ANOVA test, after checking the dataset for compliance with the homoscedasticity and normality assumptions. Post hoc comparisons were conducted using Tukey's HSD test.
biomass can be influence the chipper performances [25], so we also are oriented to evaluate other grinding systems. At the central yard, rootless trees were chipped, while complete trees were ground with a robust hammer mill and cleaned, to remove soil and other contaminants sticking to the rootstocks. Usually, biomass fuel derived from rootless trees does not present any challenges for the combustion plants, while biomass fuel produced from complete trees requires cleaning to reduce ash content below 10%. If this threshold is exceeded, the buyers apply penalties on the final payments. Both biomass fuel types were loaded on roll-on/roll-off containers and hauled to the power plant with truckand-trailer rigs. A tracked excavator (Hyundai 140LCD7), a mobile chipper (Pezzolato 1000/1000), a heavy shredder (Doppstadt DW 30/ 60) and the rotary sieve (Farwick Mustang) were used for comminution and cleaning. The bulk density of the ground comminuted biomass was calculated in compliance with the standard UNI EN 15103:2010, while as far as the means of transport are concerned, the density has always been obtained from the ratio between transported weight and volumetry. Random samples were collected before and after cleaning in the rotary sieve and analyzed for the presence of soil contaminants. At the same time, contamination before sieving was estimated by determining the mass getting into the sieve, as well as the mass of the two main piles produced by the sieve, and namely: the clean chip pile and the contaminants pile. During hauling, the average speed of three trips was recorded for each of the 4 hauling treatment (articulated truck or truck-trailer, transporting compacted or loose feedstock). Overall, the vehicles travelled on 39 unpaved roads, 85 ordinary roads, and passed through 48 inhabited centers. Where available the drivers recorded fuel consumptions using their on-board fuel meters. The total cost of the mechanical intervention was calculated on the basis of working capacity (h ha-1, measured) and the listed prices of personnel, fuel and subcontracting services In particular, personnel cost was set at 15€ hour−1. Without on-board fuel meter the fuel
3. Results and discussion 3.1. Extraction and piling To our knowledge, the topic of the present work is rather specific because no other work about complete-tree harvesting of terminated orchards can be found in the recent bibliography. So far, all works about complete-tree harvesting come from the forest sectors, and the most recent one is over 10 years old [28]. Similarly, few works deal with the recovery of aboveground wood from depleted orchards [7,20], while many others tackled rootstock removal after termination [11,19]. In this way, the comparison of our results with similar studies remains difficult. The productivity of extraction and piling of complete trees at the field's edge (Fig. 3) was about 0.5 ha day−1. Complete tree extraction was the most time-consuming task requiring 13.1 h ha−1, while piling needed just 2.2 h ha−1 (Table 1). As a result, tree extraction accounted for the 88% of the cost per hectare. Though hardly comparable, the data are lower than those required to cut, harvest and pile the aboveground
Fig. 3. Compacted biomass stored in the field. 3
Biomass and Bioenergy 130 (2019) 105378
A. Assirelli, et al.
Table 1 Productivity and main costs of extraction and piling of the whole tree.
−1
Working capacity (h ha ) Machine cost (A) € h−1(a) € ha−1 Fuel (B) € l−1(b) Hourly consumption (l h−1) € ha−1 Personnel (C) € h−1(c) € ha−1 Total (A + B + C) € ha−1
Extraction
Piling
13.1
2.2
75.0 982.5
50.0 110.0
0.89 20.0 233.2
0.89 28.0 54.8
15.0 196.5
15.0 33.0
1,412.2
197.8
Fig. 4. Loading time (mean ± SD) for the truck or the articulated truck in the field. Different letters indicate a difference for P ≤ 0.0001 according to Tukey's HSD test.
Notes. a Source [27]. b Source [26]. c Labour cost = 15 € hour−1 = hour worksite time, including delays.
(43 vs 32 min for the truck-trailer combination and 22 vs 15 min for the articulated truck). However, compaction allowed a significant increase of payload, which likely offset the additional time consumption. The additional time required for compaction was lower for the truck-trailer combination (11 min) than for the articulated truck (13 min). Loading time was shorter for the truck compared with the trucktrailer combination, both when compacting the load (0.36 vs 0.47 min m−3) and when leaving it uncompacted (0.28 vs 0.40 min m−3) (Fig. 4). The loading time of the loose material in the truck-trailer combination was comparable with that of the compacted biomass in the truck (0.36 vs 0.40 min m−3). Although in the trucktrailer combination the vehicles to load were two, the simplified loading (loose) allowed to reduce the average time per loaded volume. Such a result must be kept into account in defining the most cost-effective supply chain. Hauling time was unaffected by biomass compaction (Fig. 5), but it was dependent on truck type (with or without trailer). After compaction, the payload of the truck-trailer, the most common logistic transport system increased by 26.1% compared to the uncompacted treatment, exceeding in some cases 11 t, corresponding to a bulk density of 196 kg m−3. However, the weight of the load and vehicle manoeuvrability affected the speed maintained during transportation. On the road network used for the trips, within the same kind of vehicle, a different type of compaction showed the same transport times and hourly costs. Transport time was not affected by the compaction of the biomass (Fig. 5), but mainly depended on the type of truck (with trailer or articulated) and therefore also on its maneuverability. After compaction, the payload of the truck is increased by 21% compared to the uncompacted biomass for the same vehicle, exceeding in this case the 20 t load capacity with the same volume. However, the weight of the load and the maneuverability of the vehicle affected the speeds
biomass of a kiwi orchard as reported by Ref. [20] which overall needed about 20 h ha−1. In our study, compaction of piles allowed increasing the performance of the logistic chain and facilitated unloading of the biomass at the central yard. Complete trees needed cleaning from soil particles. The presence of contaminants (soil and stones) in wood fuel is a problem both on the pruning collection [3] and to an even greater extent for rootstock recovery [19]. Inorganic contaminants determine an increase of ash content and a decrease of calorific value: for that reason, highly contaminated fuel loads are often rejected on arrival at the plant gates [18,19]. Pear rootstocks may contain 54–75% in weight of soil soon after the extraction [18]. In a work on vineyard stumps [19], soil contamination decreased from 6.6-8.9% to 4.3–5.1% after six months of storage, depending on the rootstock type. To reduce contamination, complete trees were passed through a shredder and a rotary sieve. Although not validated statistically, the system tested in the present study gave positive results regarding the amount of soil removal and, hence, the overall decrease of soil particle pollution. Samples collected before cleaning contained until 18–20% of soil particles, while samples collected after cleaning only contained from 5 to 7%. Such values are comparable with those reported by Ref. [19] for vineyard rootstocks, although here they refer to the complete tree in our study, cleaning recorded the same productivity as shredding, so that the two tasks were part of one same sequence. However, cleaning required additional equipment and personnel and determined an increase of biomass processing cost. The experiment demonstrates the successful application of industrial machines borrowed from the earthmoving and demolition sectors [7]. Rootless tree elements were comminuted with a forestry chipper and the final product was deemed ready for direct delivery to the biomass power plant without any need for additional processing. In both cases there was the need to set up a separate area inside the farm to optimize the efficiency of the machines.
3.2. Loading and hauling Transport of loose or compacted complete tree biomass could influence the reduction of soil particle pollution of the biofuel following the partial breakage resulting from rootstock compaction. In the open field, biomass compaction had a significant influence also on loading time. On average, loading a truck-trailer combination took longer than loading a articulated truck, although the truck-trailer combination present a smaller volume capacity (55 m3 vs 90 m3). In both cases, biomass compaction resulted in an increase of loading time
Fig. 5. Total time of hauling of loose and compacted feedstock from the field to the farm centre. Different letters indicate a difference for P ≤ 0.001 according to Tukey's HSD test. 4
Biomass and Bioenergy 130 (2019) 105378
A. Assirelli, et al.
present work, Pezzolato PTH 900/660 in Ref. [20] and a conventional drum type developed for forestry in Ref. [7]. The shredder operated a rough comminution (pre-grounding) of the complete plants and the product was then processed by a rotary sieve which removed much of the contaminants. The combination of these two machines showed a working capacity of 33.3 t h−1 and an overall hourly consumption of 40 l h−1: 31 l h−1 consumed by the shredder and 9 l h−1 byrotary sieve. This additional step increased the fuel consumption and hence the structure of the cost. On the other hand, the use of the rotary sieve reduced contamination and substantially improved the quality of the final product. In this case the effect has a particular value because, as discussed above, complete trees with the roots attached contain a greater amount of soil that must be removed. The wood biomass obtained following chipping (wood chips) or the pre-treatment (shredding) were transferred to the energy plant using the same transport logistics (truck-trailer and/or articulated truck). An exception may be the case when the pre-ground material was reprocessed to produce wood chips for specific needs. The present study represents the first case of application of preground having a cleaning function, previously limited to wood chips [3].
Fig. 6. Amount of hauled biomass (t) with different degrees of comminution.
maintained during transport, especially due to the curves and the times of restart from the intersections. However, these differences did not show significant values given the average loads considerably lower than the potential of the vehicles. From the data collected on the route used for the trips, for the same vehicle, both the compacted and the loose load showed the same transport times and hourly cost, reducing the hourly transport cost (€ t−1) for a greater load capacity. During the surveys, the transport of different biomass treatments (complete-tree, pre-ground and wood chips) was monitored on ordinary working conditions. Each load had a different density which, in turn, led to a variable capacity for biomass delivery (Fig. 6). In all cases, the payload of the semitrailer was higher than that of the road train, thanks to its greater volume capacity. When biomass was transported in the form of wood chips, the payload was higher compared with pre-ground biomass, due to its coarser texture and resulting lower bulk density. In particular, mean payload decreased from 27.5 t to 25.0 t for the semitrailer. The transport of complete trees resulted in a much lower payload: 10.4 t for the truck and 16.1 for the semitrailer. Pre-grounding proved to be an interesting solution, as it allowed increasing payload to 18.6 t on the road train and to 25.03 t on the semitrailer - values that are not too far from those obtained with wood chips. The different mode of comminution affected also the bulk density of the feedstock: for the whole non-compacted plants the bulk density was 155 kg m−3 that almost doubled for the wood chips (305 kg m−3).
4. Conclusion In the present work, the recovery of complete trees from orchards at termination was studied and an optimized collection chain was analyzed. The collection of complete trees in a single pass appears as a promising technique to reduce delivered cost. However, unlike the rootless trees that are directly chipped, the proposed system included an additional step in which the complete trees were pre-grounded and cleaned. This passage allowed to abate the contamination from 18-20% to 5–7%, well below the threshold of acceptability by most power plants For shredding and cleaning, it was necessary to identify a dedicated area within the farm in order to allow an efficient processing of the biomass, to reduce the permanence in the field, to limit the cost and the environmental impact. Finally, the compaction of the biomass inside the truck brought positive results in terms of transport cost and cleaning efficiency. The step of pre-grounding allowed to attain a payload (18.6 t on the road train and to 25.03 t on the articulated vehicle) comparable with the complete comminution in wood chips. As a result, the advantages in relation to the distances to be covered can make this collection and delivery system even more effective. The work represents just a preliminary experience, which should be repeated on a range of different environmental, agronomic and logistical conditions. However, to our knowledge, th is the only available experience of complete-tree harvesting in terminated orchards. In fact, this early experience has encouraged some companies to design and implement different collection systems for a better exploitation of biomass.
3.3. Chipping, pre-grounded and cleaning Once harvested and loaded, complete trees were moved to the farm centre and then followed two different paths (Fig. 1): plants without a rootstock were directly chipped with a wood chipper, while plants complete with rootstocks were treated with a shredder and a rotary sieve. In the present study, the wood chipper showed an operational capacity of 22 t h−1 and an hourly fuel consumption of 42 l h−1. Productivity was within the range (15–30 t h−1) reported by Spinelli (2011) for the recovery of forest residues [29]. The same author showed that chipping performed at the field's edge on non-industrial short-rotation forestry of poplar might vary from 28 to 34 t h−1 [30]. However, most of the data on chipping performance are available for forest residues for which a huge bibliography exists. A possible comparison may be made with [7] where the chipping of peach, apple and plum trees (without roots) with a self-feeding chipper or a drum chipper fed by a separate loader required a total work time of 439 and 251 s t−1 respectively, corresponding to 8 and 14 t h−1. The performance of the wood chipper used in our study was higher than [7], but the hourly fuel consumption reported by Ref. [7] was 40.5% lower (25 l h−1). The productivity observed by Ref. [20] on the removal of kiwi plantation was even lower. With a production of 20.6 tDM ha−1 and a chipper productivity of 0.21 ha h−1, productivity was in fact 4.3 t h−1. The different feedstock types and chipper models used in these studies may account for the observed differences: Pezzolato 1000/1000 in the
5. Notes Reference to specific makes and models is solely made to help readers to assess the study correctly, and it does not involve any endorsement of specific makes and models to the exclusion of similar machines produced by other manufacturers. Acknowledgements This work was supported by theItalian Ministry of Agriculture (MiPAAFT) under the AGROENER project (D.D. n. 26329, 1 april 2016) - http://agroener.crea.gov.it/. The authors would like to thank the Enerlegno ltd of Casemurate (Ra) Italy, bioenergy company operates in the forestry and agricultural sector for the production of woody biomasses destined to the energy purpose for his technical support in equipment and field availability. 5
Biomass and Bioenergy 130 (2019) 105378
A. Assirelli, et al.
References
[16] M.A. Mendìvil, P. Munoz, M.P. Morales, M.C. Juàrez, E. Garcia-Escudero, Chemical Characterization of pruned vine shoots from La Rioja (Spain) for obtaining solid bio-fuels, J. Renew. Sustain. Energy 5 (3) (2013). [17] W. Cichy, M. Witczak, M. Walkowiak, Fuel properties of woody biomass from pruning operations in fruit orchards, Bioresour. 12 (3) (2017) 6458–6470. [18] G. Picchi, L. Pari, A. Scarfone, M. Barontini, R. Spinelli, Unearthing the hidden resource: biomass from rootstock recovery, Biofuels, Bioprod. Biorefining 6 (2016) 246–256, https://doi.org/10.1002/bbb.1643. [19] L. Pari, A. Scarfone, V. Alfano, S. Bergonzoli, F. Gallucci, E. Santangelo, Testing open-air storage of stumps to provide clean biomass for energy production, Energies 10 (2017) 1725, https://doi.org/10.3390/en10111725. [20] M. Manzone, F. Gioelli, P. Balsari, Kiwi clear-cut: first evaluation of recovered biomass for energy production, Energies 10 (2017) 1837, https://doi.org/10.3390/ en10111837. [21] R. Spinelli, G. Aminti, F. De Francesco, N. Magagnotti, L. Pari, Test of a new mobile machine for comminuting and cleaning rootstock waste, Biofuels, Bioprod. Biorefining 12 (2018) 949–957, https://doi.org/10.1002/bbb.1896. [22] ISTAT (Istituto Nazionale di Statistica), Principali coltivazioni legnose agrarie, Available online: https://www.istat.it/it/archivio/124365 , Accessed date: 29 March 2018. [23] M. Strandgard, P. Turner, L. Mirowski, M. Acune, Potential application of overseas forest biomass supply chain experience to reduce costs in emerging Australian forest biomass supply chains, a literature review, Aust. For. 82 (1) (2019) 9–17 https:// doi.org/10.1080/00049158.2018.1555907. [24] L. Bodria, G. Pellizzi, P. Piccarolo, Meccanica Agraria vol II: la meccanizzazione, Edizioni Il Sole 24ORE, Bologna, Italy, 2006. [25] A. Assirelli, V. Civitarese, R. Fanigliulo, L. Pari, D. Pochi, E. Santangelo, R. Spinelli, Effect of piece size and tree part on chipper performance, Biomass Bioenergy 54 (2013) 77–82. [26] Camera di Commercio Agricoltura, Industria e Artigianato Provincia Forlì Cesena, Nota Informativa sui Prezzi dei Carburanti, 30/09/2018. Available online: https:// www.romagna.camcom.it/download/regolazione-del-mercato/prezzi/listinoprodotti-petroliferi/-listino-prodotti-petroliferi-del-30-09-2018/-listino-prodottipetroliferi-del-30-09-2018.pdf?DWN=4946(accessed on 26 November 2018). [27] APIMAI, Associazione Provinciale Imprese di Meccanizzazione Agricola e Industriale, Tariffario 2018 per le Provincia di Forlì-Cesena e Rimini, 2018 Available online: http://www.caiagromec.it/sites/unima.it/files/tariffari/apima_ libretto_2018_8.pdf , Accessed date: 4 December 2018. [28] R. Spinelli, N. Magagnotti, G. Picchi, Complete tree harvesting as an alternative to mulching in early thinnings, For. Prod. J. 59 (2009) 79–84. [29] R. Spinelli, Supply of wood biomass for energy purpose: global trends and perspectives, In: Proceedings of the 22nd Annual Meeting of the Club of Bologna, November, 13-14. [30] R. Spinelli, J. Schweier, F. De Francesco, Harvesting techniques for non-industrial biomass plantations, Biosyst. Eng. 113 (4) (2012) 319–324.
[1] L. Pari, A. Suardi, E. Santangelo, D. García-galindo, A. Scarfone, V. Alfano, Current and innovative technologies for pruning harvesting: a review, Biomass Bioenergy 107 (2017) 398–410, https://doi.org/10.1016/j.biombioe.2017.09.014. [2] R. Spinelli, N. Magagnotti, C. Nati, Harvesting vineyard pruning residues for energy use, Biosyst. Eng. 105 (2010) 316–322, https://doi.org/10.1016/j.biosystemseng. 2009.11.011. [3] A. Acampora, S. Croce, A. Assirelli, A. Del Giudice, R. Spinelli, A. Suardi, L. Pari, Product contamination and harvesting losses from mechanized recovery of olive tree pruning residues for energy use, Renew. Energy 53 (2013) 350–353, https:// doi.org/10.1016/j.renene.2012.12.009. [4] N. Bilandzija, N. Voca, T. Kricka, A. Matin, V. Jurisic, Energy potential of fruit tree pruned biomass in Croatia, Span. J. Agric. Res. 10 (2) (2017) 292–298. [5] D. Garcìa-Galindo, M. Gòmez-Palmero, P. E, S. Germer, L. Pari, V. Alfano, A. Dyjakon, J. Sagarna, S. Rivera, C. Poutrin, Agricultural pruning as biomass resource: generation, potentials and current fates. An approach to its state in Europe, 24th Eur. Biomass Conf. Exhib. 6-9 June 2016, 2016, pp. 1579–1595. Amsterdam. [6] A. Dyjakon, J. Boer, P. Bukowski, F. Adamczyk, P. Frackowiak, Wooden Biomass potential from apple orchards in Poland, Drewno 59 (198) (2016) 73–86. [7] G. Picchi, L. Pari, G. Aminti, R. Spinelli, Cost-effective biomass supply from orchard termination with highly-mobile low-investment equipment, Biomass Bioenergy 94 (2016) 78–84. [8] G. Picchi, G. Aminti, R. Spinelli, Dai frutteti cippato “competitivo” rispetto ai valori di mercato, Terra Vita 4 (2014) 46. [9] V. Civitarese, S. Faugno, R. Picchio, A. Assirelli, G. Sperandio, L. Saulino, M. Crimaldi, Production of selected short-rotation wood crop species and quality of obtained biomass, Eur. J. For. Res. 137 (4) (2018) 541–552. [10] S. Faugno, V. Civitarese, A. Assirelli, G. Sperandio, L. Saulino, M. Crimaldi, M. Sannino, Chip quality as a function of harvesting methodology, Chem. Eng. Trans. 58 (2017) 271–276. [11] J. Laitila, Y. Nuutinen, Efficiency of integrated grinding and screening of stump wood for fuel at roadside landing with a low-speed double-shaft grinder and a star screen, Croat. J. Eng. 36 (2015) 19–32. [12] R. Picchio, S. Verani, G. Sperandio, R. Spina, E. Marchi, Stump grinding on a poplar plantation: working time, productivity, and economic and energetic inputs, Ecol. Eng. 40 (2012) 117–120, https://doi.org/10.1016/j.ecoleng.2011.11.012. [13] R. Spinelli, C. Nati, N. Magagnotti, Harvesting and transportation of root biomass from fast-growing poplar plantations, Silva Fenn. 39 (4) (2005) 539–548. [14] D. Duca, G. Toscano, A. Pizzi, G. Rossini, S. Fabrizi, G. Lucesoli, A. Servili, V. Mancini, G. Romanazzi, Ch Mengarelli, Evaluation of the characteristics of vineyards pruning residues for energy applications: effect of different copper-based treatments, J. Agric. Eng. 47 (1) (2016) 22–27. [15] J. Werkelin, B.J. Skrifvars, M. Zevenhoven, B. Holmbom, M. Hupa, Chemical forms of ash-forming elements in woody biomass fuels, Fuel 89 (2010) 481–493, https:// doi.org/10.1016/j.fuel.2009.09.005.
6