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The woody biomass resulting from pruning and replacement operations of different orchards can become fuel in biomass-fired power plants. The technologies currently used, borrowed from not agricultural specific solutions and often derived from the forestry sector, offer benefits on machine performance but, on the other hand, do not allow the product obtained to meet the quality and cleanliness requirements of biopower plants. The present work aims to examine and match the types of orchards and management with the available explant and biomass management technologies, highlighting advantages and limitations under the various aspects of the complete logistic chain: harvesting, transporting and chipping. The main novelty is the possibility of applying specific technologies to optimize the costs and the quality of the end product. The data obtained show specific correlations between the mandatory compliance of the end product quality and commercial cleanliness standards, the type of orchard, and the used technique. Furthermore, the working times of the different collection lines do not differ significantly, opening issues on the possibility of setting up targeted interventions for fruit tree explantation and the subsequent woody biomass management., Proceedings of the 30th European Biomass Conference and Exhibition, 9-12 May 2022, Online, pp. 262-265

Chipping is an essential element in the energy supply chain and mobile chippers are very popular because they can work directly in the forest or at the roadside landing. Due to space constrain, drum chippers are dominating forest biomass operations. Drum chipper are less efficient then disc chipper but they are also less sensitive to feedstock quality. Drum chippers come in two main design types: closed drum with full-length knives and open drum with staggered narrow knives. The goal of this study was to analyse the specific effect of these design types on productivity, fuel consumption and product quality, using different raw material types. For this purpose, two commercial chipper models with almost identical characteristic were selected to represent the alternative drum designs. Both machines were fed with two different feedstock types: chestnut logs and chestnut branches. The study included 12 repetitions per combination of drum design, feedstock type and knife condition (new or worn out) for a total of 2 x 2 x 2 x 12 = 96 repetitions. Both chippers were attached to the same instrumented tractor, and all product obtained from each chipping bout was blown into big bags and weighed with a load cell attached to a forklift. The study showed that the closed drum design was better suited to handle branch material, compared to the open drum design, especially when knives were dull. Under these conditions, productivity was higher, fuel consumption lower and chip quality better for the closed drum design. No significant differences between the two designs were found when processing logs or when the knives were new. In general, the performance of both designs was significantly affected by feedstock type and knife wear.

In central Italy, the increasing demand for fuel chips and the epidemic spread of maritime pine bast scale have favored the development of large-scale industrial logging operations. After years of extensive commercial trials, local operators have developed their own industrial harvesting systems, through a wise mix of Scandinavian and North American methods. The result is original and effective, and allows keeping harvesting cost below 20 EUR gt -1. The study compared terrain chipping with roadside chipping, as applied to the coastal pine stands of Tuscany. Under the conditions of our study, roadside chipping was over four times more productive than terrain chipping, and it allowed reducing harvesting cost by one third (12.3 vs. 18.3 EUR gt -1). Despite the intense use of diesel, total fossil energy inputs accounted for less than 3% of the potential energy in the wood chips. Terrain chipping and roadside chipping yielded 36 and 47 times the energy they used, respectively. The coexistence of the two systems was most interesting. The harvesting systems described in the study perform best in clear-cuts, but they can also work in partial cuts, including thinning operations. They are actually used in thinnings in the same Regional Park of San Rossore, although their productivity is lower than in clear-cuts.

Short rotation coppice (SRC) is one of the most promising sources of woody biomass for energy in the frame of the European renewable energy strategy. While the study of improved clones and growing techniques is extremely important for future developments, the availability of reliable and cost effective harvesting systems is crucial for the very existence and sustainability of any SRC program. In fact, harvest and logistics of biomass can constitute up to 70% of the overall production costs of SRC biomass production. At present, commercial harvest operations in Italy are accomplished with modified foragers equipped with dedicated SRC headers. The present study provides an overview of the main characteristics and performance of four different models of forager/SCR header deployed in Italy., Proceedings of the 19th European Biomass Conference and Exhibition, 6-10 June 2011, Berlin, Germany, pp. 678-679

Industrial poplar plantations represent a strategic source of wood products for many countries. Harvested after 10 to 30 years, they yield about 200 t ha-1 of timber and 100 t ha-1 industrial wood. The latter is obtained from poplar tops, which can be converted into chips, or a mix of pulpwood and chips. The study compared four options to process poplar tops. Alternatives derived from the intersection of two product strategies (pulpwood and chips, or chips only) with two pulpwood processing methods (manual or mechanized). Both mechanization and simplification (only one product) succeeded in reducing production cost, but the former had a stronger effect. The tests demonstrated that all options were cost-effective and could return some profits. However, the exclusive production of chips offered lower profits, compared to an articulate product strategy aimed at maximising value recovery. In the case of Italian poplar plantations, the price difference between pulp and chips is generally larger than the cost reduction obtained with integral chipping. Similar conclusions were reached by other authors working with spruce and beech in Central Europe. Of course, this is only true for the current price levels of pulpwood and chips: results may change, if this price balance will be altered by the growing demand for biomass fuel.

The recovery of agricultural woody residues for energy production is arising a growing interest in European Countries. Many aspects must be better understood in order to fully control the factors defining the technical and economic viability of field-to-boiler biomass procurement projects. A comprehensive overview of the available equipment and its main characteristics may be useful for the definition of the best solutions to be implemented according to the vineyard characteristics, the professional level required (ranging from farm level self­production to contractors), and the type of final user (farm size boiler to district heating plants). Italian manufacturers propose to the local market a wide choice of machinery (over 60 models) dedicated to the harvest and transformation of agricultural residues, with a specific attention to vineyard residues. These machines can be roughly divided in two main groups, balers and comminuters. Balers can be both purpose designed machines (smaller and agile) or the lighter models of common agricultural balers. Comminuters are generally mulchers equipped with a bin or an expulsion system for loading the biomass onto a trailer. The present work reports a brief description of the results of the studies conducted by CNR-IVALSA on vineyard residues harvesters., Proceedings of the 19th European Biomass Conference and Exhibition, 6-10 June 2011, Berlin, Germany, pp. 542-543

The growing interest in forest biomass has made chipping increasingly popular all across Europe. Many operators have equipped for the purpose, but the large variety of working conditions found in the European forests makes it difficult to correctly estimate the productivity of each specific operation, leading to uncertainty in crucial decisions, such as: operation scheduling, price setting, machinery selection and acquisition. In 2001, the Italian National Council for Research (CNR) and the University of California (UC) developed a spreadsheet freeware capable of returning reliable estimates of chipping productivity and cost, on the basis of user-defined input data. The model is still available from the CNR website and is the object of frequent downloading and inquiries. Such model contains a set of predictive equations derived from the results of 102 field trials, conducted with 30 different machines, under a range of working conditions. In order to facilitate comparison with other estimates and to achieve methodological transparency, the equations are assembled into a simple Microsoft Excel workbook, and the costs are calculated with standard costing methods currently used in Forest and Agricultural Engineering. Since then CNR has continued to work on the subject, with the goal of updating and refining the model. Such work has included 45 validation tests and a separate study on the delay (idle) time typical for different chipping operation layouts. The study was concluded in 2009 and confirms that the model developed by CNR can provide reliable estimates of chipper productivity under a range of operational conditions. Authors believe that such a model can assist European foresters in keeping ahead with the growing biomass sector, thus helping them to seize an important business opportunity.

The exploitation of forest biomass may offer important benefits in terms of environmental protection and local employment, but the development of an effective forest biomass chain is hindered by the lack of techniques for tapping the resource at reasonable costs.

Nine chippers were tested for particle size distribution, in order to a) see how chips produced with these machines matched the quality specifications set by the district heating plants of Northeastern Italy and b) detect significant differences between machines. The benchmark was set by collecting chip samples from fourteen district heating plants in the region of interest. The effect of operator skill was minimized and all machines were fed with the same assortment: logs, supplied in lengths varying between 2.4 and 6 m. All logs had similar moisture contents, which typically ranged between 33 and 37 % on a fresh weight base. Mobile in-woods chippers fed with limb-free logs produce high-quality chips, whose particle size distribution matches that of the best chips normally fed to the Italian district heating plants. Indeed, all the tested machines produced chip samples containing almost no oversize particles, very little fines (0.5 to 1 %), and a large majority of chips within the 3-45mm range (95 to 99 %), except the auger-equipped Laimet, which is designed to produce larger chips. There were statistically significant differences between machines and machine types, which were not affected by possible variations of the tree species processed.

A new industrial chipper was designed for use in short-rotation forestry plantations, which requires high productivity and all- round mobility. The new machine was tested at seven different sites, representative of the main work environments negotiated by modern agroforestry contractors. The tests produced 114 chip containers, or 929 tonnes of fresh chips (ca. 3,500 m3 of loose chips). Productivity varied between 28 and 55 tonnes of fresh chips (or 105 and 194 m3 of loose chips) per productive work hour, excluding delays. Pure chipping productivity (calculated on chipping time only) was higher and peaked at 70 tonnes of fresh chips or 242 m3 of loose chips per hour. Fuel consumption ranged from 1.38 to 2.15 litres of diesel per tonne of green chips, or from 0.39 to 0.59 litres of diesel per m3 of loose chips. Machine utilization rate varied between 69 and 83 %. Highest efficiency was reached at plant yards, due to optimum pile layout, wide space availability and easy chip discharge. Due to its remarkable off-road mobility, the new machine can restore efficiency to terrain chipping, provided that the terrain is flat and solid, the piles are duly arranged and a large enough support fleet is available for moving the chips to their destination.