An agile chipper truck for space-constrained operations

doi:10.1016/j.biombioe.2015.06.017

Biomass and Bioenergy

Volume 81, October 2015, Pages 137-143

https://doi.org/10.1016/j.biombioe.2015.06.017 Get rights and content

Highlights

•
The same chipper-truck and operator were tested across Europe.
•
Productivity was high, and in line with expectations (∼20 t h⁻¹).
•
Regional differences had a limited impact on chipper performance.
•
Operational efficiency was highest in Northern Europe, due to better logistics.
•
Chipper performance was affected by knife wear, screen size and cut length.

Abstract

A new chipper-truck was developed for extending the benefits of industrial chipping to space-constrained landings, normally inaccessible to industrial operations. The new machine was taken for a European test tour, so that it could be tested under conditions considered typical of Mediterranean, Alpine, Central and Nordic Europe. The same machine and operator were used for all tests, which lasted 65 h and produced over 100 chip containers. Productivity varied between 13 and 19 tonnes of green chips per scheduled hour, inclusive of all delays. Fuel consumption ranged from 1.8 to 2.8 dm³ of diesel per tonne of green chips. Machine utilization ranged from 68 to 89%, and it was highest in the Nordic trials, due to the use of pre-parked containers, which dramatically reduced the occurrence of interaction delays. Regional differences were only related to operational layout and organization, which set the Nordic trial apart from all others. Knife wear and screen size had a major impact on chipper performance. The same accounted for cut length. Production of small chips is only justified when the market offers premium prices for this assortment.

Introduction

The increased global competition for finite fossil fuels and the need to mitigate climate change have generated a strong universal interest and demand for renewable fuels [1]. In Europe, forests are still the main source of wood fibre and are largely underutilized [2]. In general, forest biomass operations are hampered by the limited access and availability of forest road infrastructure, which is reduced to the essential, given the wide dilution of the forest resource [3]. Insufficient landing space poses specific constraints to biomass recovery operations, which are based on roadside chipping. That requires enough space to accommodate a chipper and the chip vans necessary to collect the product and move it to the end user. Both chipping and transportation efficiency are maximized when using large industrial units, but these equipment are difficult to maneuver in narrow landings, commonly available at most forest sites. Transitioning to small-scale machinery may solve the limited space problem, but may result in a high production cost, limiting the financial sustainability of biomass recovery. One solution is to upgrade the forest road network and build suitable landing sites. However, this is a long-term investment that requires a large capital outlay. Besides, road-building is a complex and delicate business that must be carefully planned and executed, in order to contain cost and prevent hydrological problems. The alternative is developing advanced industrial equipment that is both maneuverable enough to negotiate narrow roads, and powerful enough to operate at high levels of productivity.

The goal of this study was to determine the performance of a new industrial chipper, specifically designed for negotiating poorly accessible sites. In particular, the study aimed at determining chipper productivity, fuel efficiency, utilization, mechanical availability and product quality under a wide range of conditions. For this reason, the geographic scope of the study was fully European, and the machine was tested in some of the main forest regions of Europe, including: Mediterranean, Alpine, Central and Nordic.

Section snippets

Materials

The new chipper analysed in this study was a Pezzolato Hacker-truck PTH 1200/820 (www.pezzolato.it). This machine is a new generation chipper-truck, where the two-bladed drum chipper is powered by the truck's engine through a dedicated power take-off. Total engine power is 400 kW, which fully qualifies this machine for industrial use [4]. At the same time, the truck base is a three-axle compact unit with a turning radius of 7 m, specifically designed for negotiating narrow, steep roads (Fig. 1

Methods

The authors carried out a typical time-motion study, designed to evaluate machine productivity and to identify those variables that are most likely to affect it [6]. Each work cycle was timed individually, using hand-held field computers, running dedicated time study software. Productive time was separated from delay time [7], and the filling of a chip container was considered as a cycle. All delays were included in the study, and not just the delays below a set duration threshold, because such

Results

One of the main differences between regions was in the material being chipped, which represented locally available feedstock. In particular, the forest residues chipped in Germany were substantially wetter than any of the other feedstock chipped elsewhere (49% vs. ca. 33%). This difference proved highly significant, according to the Kruskal–Wallis non-parametric test (p < 0.0001).

Mechanical availability varied between 94 and 99%, as expected for a new machine. The actual machine utilization

Discussion

Covering the main forest types of Europe in one single study encountered obvious logistical constraints, which limited our capacity to implement a strict experimental design, with all combinations of factors properly represented by balanced data sets. To overcome these limitations, statistical analysis was conducted with specific techniques considered as robust against violations of conventional statistical assumptions, including unbalanced data sets and non-normal distribution of data.

Conclusions

The study confirmed the good performance of the innovative chipper-truck developed within the framework of the INFRES project (Innovative and effective technology and logistics for forest residual biomass supply in the EU), and of the chipper truck concept in general. Chipper-trucks offer a compact and agile alternative to truck-mounted chippers. While they cannot match the off-road mobility of forwarder-mounted chippers, they are much easier to relocate between operations. Furthermore,

Acknowledgements

The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2012-2015) under grant agreement n°311881 (INFRES Project). The Authors gratefully acknowledge the assistance with data collection received from Ms. Lombardini (IVALSA/SKOGFORSK) and Ms. Walkiewicz (FELIS).

References (19)

G. Berndes et al.
The contribution of biomass in the future global Energy supply: a review of 17 studies
Biomass Bioenergy
(2003)
K. Ericsson et al.
Assessment of the potential biomass supply in Europe using a resource-focused approach
Biomass Bioenergy
(2006)
R. Spinelli et al.
Determining long-term chipper usage, productivity and fuel consumption
Biomass Bioenergy
(2014)
R. Spinelli et al.
A survey of Italian chipping operations
Biomass Bioenergy
(2001)
R. Spinelli et al.
Analyzing and estimating delays in wood chipping operations
Biomass Bioenergy
(2009)
A. Facello et al.
The effect of chipper cut length on wood fuel processing performance
Fuel Process Technol.
(2013)
C. Nati et al.
Wood chips size distribution in relation to blade wear and screen use
Biomass Bioenergy
(2010)
A. Facello et al.
The effect of knife wear on chip quality and processing cost of chestnut and locust fuel wood
Biomass Bioenergy
(2013)
R. Spinelli et al.
Determining the biomass fuel potential of vineyard pruning residues
Appl. Energy
(2012)

There are more references available in the full text version of this article.

Cited by (16)

Determining the repair and maintenance cost of wood chippers
2019, Biomass and Bioenergy
Citation Excerpt :
On the other hand, the empirical figures obtained from this study can be compared with the theoretical figures reported in other studies about chipper cost. Most such studies present chipper maintenance cost as a percent of chipper depreciation, and estimate it at 75% [22], 80% [23], 100% [24] or 110% [25] - all of which fall below the 120% value reported here. On the other hand, those studies that present maintenance cost as a percent of total chipping cost generally exceed the mean 14% figure found in this study and point at 18% [26] or 20% [27].
Chipping weighs heavily on the total delivered cost of wood fuel, which calls for accurate chipping cost estimates. Chipper repair and maintenance cost is perhaps the most obscure among the figures required for a reliable estimate of chipping cost. To clarify this issue, the authors examined the long-term repair and maintenance records for 51 wood chippers operated by 48 chipping service contractors. Repair and maintenance represented between 1.5% and 29% of total chipping cost, inclusive of fuel and labour (mean = 14%). The ratio between total accumulated repair (TAR) cost and machine price averaged 32% and varied with total use. The relationship between total use and TAR to price ratio was explored through regression analysis, which produced a very strong model (R² = 0.8). This model predicts a TAR to price ratio of 0.64 at 10000 h, with no significant differences between tractor-driven and independent-engine machines. While the coefficients are different, the structure of this model offers a good match with the repair and maintenance cost models developed for farm tractors and other agricultural machinery. A second model was developed for estimating repair and maintenance cost as a function of fuel consumption. The study also provides reference figures for the contribution of labour cost to total maintenance cost. Farm tractors incur more repairs than preventive maintenance, contrary to the other dedicated components of the chipping operation, where preventive maintenance represents most of maintenance cost. Forestry users should make allowance for the lower structural strength of tractors and select large models.
The effect of output unit choice on detection of feedstock effects on chipper productivity and fuel consumption
2018, Biomass and Bioenergy
Citation Excerpt :
The many methods used to measure output make individual biomass production studies difficult to compare, which is further complicated by the fact that machine design might influence the measurement of the output [12]. The produced amount of chips or hog fuel has been measured in m3 chipped volume [13–18], raw tonnes [19–24], dry tonnes [16,20,21,25–29] or as energy in J or MWh [30,31]. To further confuse things, some studies measure the amount of chips in solid m3 of wood that has been chipped [31,32].
Currently different trade units are used throughout the forest energy supply chain in Sweden: chipping contractors are paid per m³ chipped volume, dry metric tonnes or MWh, hauliers per raw tonnes or m³ chipped volume and the company supplying the chips to the heating plant most often per delivered MWh. This introduces business risks for all market players, and affects studies of chipping equipment. Lately, Skogforsk has used oven dry tonnes, but stakeholders that measure chips in other units want results to be presented in these units as well. To raise awareness about output unit selection and its effect on productivity and fuel consumption studies, Bruks 806 chippers were studied when chipping spruce and beech residues. Results show that the selection of output unit affects the capacity of detecting treatment differences and the direction of such differences. Chipping productivity based on effective chipping time was higher for spruce residues when calculated using chipped volume, and for beech when calculated using raw weight. Similar trends were found for fuel consumption per product unit. As both feedstock characteristics and output measurement unit selection affects study results, a proper experimental design to control these effects is important. In many cases it is a matter of keeping feedstock constant during comparisons of machines/treatments. Care is needed when using chipped volume, as chipper settings may influence chip bulk density and thus chip volume. The use of different units throughout the supply chain reduces transparency and increases the risk for sub-optimal decisions.
Chipping operations and chip quality from mixed hardwood forests for bioenergy
2023, International Journal of Forest Engineering
Forest and biomass harvest and logistics
2022, Forest and Biomass Harvest and Logistics
Trends and perspectives in the design of mobile wood chippers
2021, Croatian Journal of Forest Engineering
A Critical Review of Comminution Technology and Operational Logistics of Wood Chips
2020, Current Forestry Reports

View all citing articles on Scopus

View full text

Research paperAn agile chipper truck for space-constrained operations

Highlights

Abstract

Introduction

Section snippets

Materials

Methods

Results

Discussion

Conclusions

Acknowledgements

Biomass Bioenergy

Biomass Bioenergy

Biomass Bioenergy

Biomass Bioenergy

Biomass Bioenergy

Fuel Process Technol.

Biomass Bioenergy

Biomass Bioenergy

Appl. Energy

Research paper
An agile chipper truck for space-constrained operations