Storage Of Wood Chips Research Articles

The effect of calcium hydroxide on the storage behaviour of poplar wood chips in open-air piles

Biomass degradation by microorganisms may cause major losses during the storage of wood chips for energy production. Poplar wood chips from short rotation coppices are especially prone to degradation with dry matter losses (DML) of up to 25% within a storage period, emphasizing the need for countermeasures. Therefore, we investigated the potential of the addition of alkaline Ca(OH)2 to the wet biomass of poplar wood chips and hypothesised that the establishment of an alkaline environment would reduce the activity of fungi, the primary wood degraders. Three industrial-scale piles (250 m³) with 0, 1.5 and 3% Ca(OH)2 were installed in Güssing, Austria and for four months (April–August 2019) the pile temperature, pH, moisture content, gas evolution (O2, CO2, H2, H2S, CH4) as well as DML were monitored. Ca(OH)2 altered the physicochemical properties of the wood chips but did not prevent biomass losses. However, as compared to literature, the DML were, compared to earlier investigations, also low in the control. In addition, cultivation methods were performed to evaluate the diversity of thermophilic microbes throughout the storage. Numerous filamentous fungi belonging to the phyla Ascomycota and Mucoromycota were isolated, being Rhizomucor pusillus, Aspergillus fumigatus, Thermomyces lanuginosa and Thermoascus aurantiacus the dominant species. Only minor differences in the fungal composition were detected as a result of Ca(OH)2 addition. Instead, clear shifts in colony forming units (CFUs) were detected as a function of progressing storage time, with a decrease of the number of propagules after four months.

Monitoring of Respiratory Health Risks Caused by Biomass Storage in Urban-Type Heating Plants

The aim of this work was to carry out long-term monitoring on the concentration and identification of phytopathogens in wood chip storage areas in urban-type heating plants. Three municipal heating plants in the central part of Slovakia were selected. The plants store biomass in large-capacity piles with a volume of 4 to 5000 m3. Samples were obtained every year in the 2017–2022 period from the surface of the piles and from a depth of 0.5 m. Their moisture content was determined in the laboratory and the microbial analysis was performed by an accredited laboratory. The average number of colonies of phytopathogens did not differ significantly in individual years. The highest number of colony-forming units per gram was achieved by the species of the genera Penicillium and Aspergillus. In terms of occurrence in individual years and the frequency of occurrence in individual samples, the most frequently recorded species were Mycelia Sterilia, Aspergillus brasiliensis, Aspergillus unguis, and Yeasts. Based on the results achieved, in the future it will be necessary to establish legislative frameworks for these risks and, at least at the national level, work procedures for individual work activities, so that the health and life of the workers of the plants, as well as residents in the vicinity of this type of plant, are not endangered.

ANALYSIS OF INTERNATIONAL EXPERIENCE TO EXPAND PRODUCTION AND SUPPLY OF WOOD CHIPS IN UKRAINE

The prospectі of wider implementation of more powerful wood biomass projects in Ukraine will lead to an increased demand of wood chips, and its increased production is expected from logging residues, which now are almost unused, as well as the continuation and possible expansion of its production from logwood. When organizing the production and supply chains of wood chips, the advanced methods of timber harvesting and the possibility of their adaptation in Ukraine should be considered, as well as to increase economic efficiency of supply, taking into account the need to save wood chips fuel properties during storage, which requires proven methods of reducing of moisture content and preventing the dry matter loss. International experience shows that production, storage and supply methods of wood chips directly affect its quality and fuel characteristics, and its efficient use as fuel must be ensured by appropriate technical solutions of boiler equipment.

Sieving and Covering of Wood Chips Improves Storability

Minimising dry matter losses during storage of comminuted forest fuels is desirable from both an economic and a sustainability perspective. This study examined fuel quality and amount of recovered energy during the storage of forest wood chips stored at full industrial scale at three locations, and the effect of sieving and covering piles with a water-resistant, vapour-permeable fabric. Sieving wood chips before storage, that is, reducing the number of fines smaller than 8 mm, reduced the cumulative dry matter losses to <2%, while cumulative dry matter losses after storage for 4–6 months using current practices, that is, unsieved and uncovered, reached 10.6%. The combined effect of storage management led to a value loss of 11.5%, while both covering and sieving led to lower losses, with the combination of sieving and covering giving a 1.3% value increase, and thus, increased storability.

Impact of stem age and winter outdoor storage on willow chip chemical composition and physicochemical properties

Willow (Salix) biomass production has been expanding dramatically in recent years with the development of phytoremediation and wastewater treatment projects and plans to build bio-refineries are increasing the future options for valorizing this biomass. In this context, winter storage of biomass after harvesting is unavoidable, due to limited shelter capacity. Questions about the impact of outdoor storage during winter and stem age at harvest time led to the establishment of an experiment on the site of Ramo®, a biomass-based products producer. Two- and three-year-old Salix miyabeana ‘SX67′ stems were chipped and piled after leaf fall in November 2018. Temperature was measured during the experiment, while physicochemical parameters and biomass composition were analyzed at the beginning and the end. The experiment showed that stem age influenced the initial biomass composition, with the two-year-old stems containing more extractives and the three-year-old stems containing more structural sugars. Heat production varied with stem age, which was reflected in the final biomass composition. A loss of extractives and an increase in lignin was measured in both stem types, while an increase in glucan, xylan and mannan was also measured in the two-year-old chips. This new information complements existing data on mass loss during wood chip storage and provides essential knowledge for future decision-making related to the development of lignocellulose value chains from bioenergy crops.

Performance of an Innovative Bio-Based Wood Chip Storage Pile Cover—Can It Replace Plastic Tarps?

There is currently great general interest in reducing the use of fossil-based materials. Fossil-based tarps are still widely used as cover for wood chip storage piles, causing additional waste or requiring further waste treatment in the supply chain. This study aimed to investigate the performance of an innovative bio-based wood chip pile cover compared to conventional treatments (plastic-covered and uncovered) in eastern Finnish conditions. The experiment evaluated the drying process during the storage of stemwood chips during 5.9 months of storage. It included the developments of temperature, moisture content, heating value, energy content, basic density, particle size distribution, and the dry matter losses of a total of six piles. As a result, the forest stemwood chips dried by 11%, with dry-matter losses of 4.3%, when covered with the bio-pile cover. Using the plastic covering, the forest stemwood chips dried by 22%, with dry matter losses of 2.9%. At the end of the experiment, the energy content in plastic-covered piles was 6.1% higher than uncovered piles and 3.1% higher than bio-pile-covered piles. While differences in the key drying performance parameters can be observed, the differences between uncovered piles and those covered with plastic tarps, as well as between the bio-based and the uncovered piles, were not statistically significant. We conclude that the bio-based cover, under the studied conditions, do not render better storage conditions than in current practices. However, our study indicates possible fossil-substitutional benefits by using a bio-based cover, which calls for further R&D work in this matter.

The economic impacts of woodchip storage optimization: Reducing material and energy loss during transportation and storage

The use of woody biomass for domestic bioenergy provides many benefits and opportunities, but also presents a challenge regarding the supply chain required for maintaining the high quality feedstock for sustained bioenergy production. This article focuses on one aspect of that supply chain – woodchip storage. To encourage the establishment of a bioenergy market and to help ensure a safe and stable fuel source, Suzanne Wetzel and Christopher Helmeste from the Canadian Forest Service, Canadian Wood Fibre Centre (CFS/CWFC) and collaborators contributed their scientific expertise to the development of a solid biofuels guide based on existing national standards from the Canadian Standard Association’s (CSA). This paper explores the potential economic impacts for bioenergy producers of implementing the CSA guidelines. These impacts include reducing material and energy loss during transportation and storage. Potential benefits were determined by cost-benefit analysis. The results of this economic impact study have significant potential implications for bioenergy producers, including the integration of economic considerations in the development of policies for biomass feedstock optimization for the Canadian bioenergy industry.

The potential of calcium hydroxide to reduce storage losses: A four months monitoring study of spruce wood chip piles at industrial scale

The objective of this study was to investigate the effect of an alkaline additive on the storage of wood chips from Norway spruce forest residues. Piles of untreated and calcium hydroxide treated wood chips (250 m3) were set up and investigated for four months. It was demonstrated that adding Ca(OH)2 to moist wood chips decreased the dry matter loss by 6%. This was attributed to the increase of the pH to a level of 8, rendering the habitat less suitable for fungal colonisation. The results suggest the set-up storage strategy as a potential alternative method for preserving wood chips when long term storage is required.

Wood Chip Storage in Small Scale Piles as a Tool to Eliminate Selected Risks

Massive use of wood biomass is usually associated with its long-term, large-scale storage in power plants and heating plants. Long-term storage of wood biomass (more than 3 months), in large volumes, brings risks from the point of view of human health or property treatment. This work aimed to verify how the long-term storage of wood chips from beech wood in small piles affects their energy properties and whether in this way it is possible to reduce the risk of fire by self-heating in piles and the volume of phytopathogenic spore production. Four experimental piles, each with a base of 4 × 4 m and a height of 2 m, were established. After 6 months, one of the piles was disassembled and samples from 0.5 m, 1.0 m, and 1.5 m height levels were taken for analysis. The results of the experiment confirmed that the energy properties of wood chips stored in small piles significantly deteriorate after more than half a year of storage. It has also been confirmed that the choice of this method of storing in smaller, spatially divided piles can lead to a significant minimization of the risk of spontaneous combustion and fire. The length of the storage period did not have a positive effect on the abundance of phytopathogen content in the stored piles. With the length of storage, only the number of identified harmful species of phytopathogens were changed and, at the same time, their number of colonies increased.

Cold air ventilation for cooling and drying of poplar wood chips from short rotation coppice in outdoor storage piles in Germany

The storage and natural drying of wood chips from short rotation coppices (SRC) in open-air piles can be related to high dry matter losses (DML) of more than 20%. Thus it should be researched, whether such loss can energy efficiently be reduced using cold air ventilation (CAV). Respectively, a dedicated channel system for sensor controlled ventilation and drying of wood chips was developed and tested in the drying process of two storage piles of poplar chips (2 × 90 m³). The ventilation of the storage piles was facilitated in two consecutive program phases: a cooling program, subsequent to the harvest in the month of March, and a drying program under more favorable weather conditions in the month of April. The characteristically high temperature rise typical for wood chip storage immediately subsequent to storage intake could be limited to an average storage pile temperature of 6.3 °C with just 41 blower operation hours due to the cooling program in the month of March. Due to the subsequent drying process in April, the storage pile could be dried further from 51.5% to 11.9% in 196 blower operation hours. The required energy input for the process of CAV, consisting of cooling and drying, amounted to 456 MJ t−1 (dry matter). At a total demand of electric energy of 5332 MJ per storage pile, a more than six times higher thermal energy advantage of 35,233 MJ was achieved. DML of 11% were measured at the end of wood chip drying using CAV.

Fuel properties, dry matter losses and combustion behavior of wood chips stored at aerobic and anaerobic conditions

Aerobic and anaerobic storage of wood chips from coniferous forest residues, coniferous energy roundwood and short rotation coppice were investigated regarding dry matter losses, energy losses and changes in fuel properties using several approaches, i.e. a field trial with 90 m3 wood chip piles, small-scale storage containers (0.5 m3) incl. greenhouse gas measurements and miniature bunker silos (1.5–2 m3). After storage, selected fuels were combusted in a 30 kW wood chip boiler and emissions (CO, NOX, TPM) were measured.Dry matter losses in fleece-covered piles were 7%–9% after 153 days of storage. Drying compensated for energy losses. Container trials achieved full anaerobic conditions in the lab reducing dry matter losses to 0.4–2% while preserving fuel properties. Methane emissions during anaerobic storage in containers were low. Anaerobic conditions could not be achieved in outdoor bunker silos due to insufficient airtightness. The mass fraction of H2O in fuels increased in bunker silos by 4.2–10.4% due to precipitation and dry matter losses up to 22% were recorded. During combustion, CO and TPM emissions were often increased significantly with materials that were stored in silos or piles compared to technically dried fuels, most likely due to changes in their woody or physical-mechanical structure and their mass fraction of H2O.Anaerobic storage might in theory be an interesting option to reduce dry matter losses but could not sufficiently be realized during this study using miniature bunker silos. For many applications, aerobic storage in fleece-covered piles seems preferable to anaerobic storage.

Development of a model for the fast analysis of polymer mixtures based on cellulose, hemicellulose (xylan), lignin using thermogravimetric analysis and application of the model to poplar wood

The storage of wood chips is associated with high dry matter losses and changes in raw material properties due to microbiological-chemical degradation processes. For a better understanding of degradation processes and their effect on wood components, very labor intensive chemical analysis of a large number of wood samples over a storage period of 6 to 9 months is necessary. The thermogravimetric analysis (TGA) of wood samples offers the possibility to considerably reduce the analysis effort while at the same time achieving a high repeat accuracy. For this purpose, a method was first developed in which the determination of characteristic values for wood analysis is possible in a staged TGA setup in a combined nitrogen and oxygen atmosphere. Based on these characteristic values, a model for the quantification of cellulose, xylan and lignin in polymer blends was developed and three polymer blends representing a broad spectrum of naturally occurring compositions in wood were analyzed to validate the model. The deviation between the polymer fractions determined by the model and used in the experiment was max. 1.37%. The developed model was then transferred to the analysis of extract-free poplar wood samples. The model results were validated by comparison with chemical analysis (NREL) and literature values. This comparison has shown that the wood constituents under consideration can be determined with sufficient accuracy using the new method. The developed method can thus serve as a basis for the development of a method for the continuous monitoring of degradation processes in wood chip storage.

The Health Evaluation of RCC Silo Using Non-Destructive Methods

A silo may be a structure for storing bulk materials. Silo is utilized in agriculture to store grain or fermented feed referred to as silage. Silo is commonly used for bulk storage of grain, coal, cement, smut, woodchips, food products and sawdust. Three kinds of silos are in widespread use today: tower silos, bunker silos, and bag silos. Every structure needs health evaluation after some time it known as condition assessment of structure. When structure complete, 10 year & found any default in structure then we need to do Non-destructive testing like Ultra-sonic pulse velocity test, Rebound hammer test and Half-cell potential meter test.

Storage of Fine Woodchips from a Medium Rotation Coppice Eucalyptus Plantation in Central Italy

Eucalyptus spp. has received attention from the research and industrial field as a biomass crop because of its fast growth and high productivity. The features of this species match with the increasing demand for wood for energy production. Commonly, the wood used for energy production is converted in chips, a material susceptible to microbial degradation and energy losses if not properly stored before conversion. This study aims at investigating two outdoor storage systems of Eucalyptus wood chips (covered vs. uncovered), assessing the variation in moisture content, dry matter losses and fuel characteristics. The class size of the material was P16, which was obtained using a commercial chipper appositely searched to conduct the study. The results highlighted how the different storage methods were influenced by the climatic condition: the woody biomass covered showed the best performances in terms of dry matter losses achieving 2.7% losses vs. the 8.5% of the uncovered systems. However, fuel characteristics displayed minor changes that affected the final energy balance (∆En = −0.2% in covered; ∆En = −6.17% in uncovered). Particle size varied in both methods with respect to the start conditions, but the variation was not enough to determine a class change, which remained P16 even after storage.

Storage of Fine Woodchips from a Medium Rotation Coppice Eucalyptus Plantation in Central Italy

Storage of Fine Woodchips from a Medium Rotation Coppice Eucalyptus Plantation in Central Italy

Storage of Wood Chips

To make forest biomass more competitive, increased efficiency in the handling and supply system is needed, thus producing high-quality fuel at a lower cost. Operating costs can be reduced if the target chip size is increased, as this increases productivity and reduces chipper fuel consumption. However, the chips need to be storedin order to meet fluctuating seasonal demand and maintain high machine utilisation. Due to biomass degradation, storage of comminuted biomass can lead to high energy losses, but can also increase fuel quality, e.g. by reducing moisture content and increasing net calorific value. This study evaluated the effects of storage on dry matter losses and differences in fuel quality of the stored biomass for three target chip sizes and three materials during six months of storage. The results showed that coarse chips had significantly lower moisture content and lower energy losses after storage than fine chips. Overall, changes during storage resulted in an economic loss of 3–4% per oven-dry ton for fine chips, but an economic gain of 2–6% for coarse chips. Thus increased target chip size can increase the competitiveness of forest biomass through decreased production costs and reduced storage costs. It can also ensure higher, more consistent fuel quality.

Influence of the particle size of poplar wood chips on the development of mesophilic and thermotolerant mould during storage and their potential impact on dry matter losses in piles in practice

For efficient provision of wood chips from agriculture and forestry these raw materials must be stored in such a way that mass and energy losses are kept as low as possible. The connections between wood chip size, moisture content, pile temperature, mould concentrations and dry matter loss were examined in practice during storage of wood chips from poplar (Populus) from SRC in covered piles for periods of seven to nine months.Similar temperature curves were measured in the piles in all trials. The curves can be subdivided into characteristic temperature-dependent phases (P) – P1 (frost), P2 (high temperature), P3 (low temperature). In piles with small chips, temperatures measured in P2 (up to 64 °C) were always higher by comparison with those measured in medium chip piles (up to 58 °C). Low mesophilic and thermotolerant mould contents (up to 3.8 lgCFU g−1) as well as low dry matter losses (up to 5.7%) were also recorded. As temperatures drop below 45 °C in P3, mould contents and dry matter losses (up to 16%) increase clearly.In the case of medium chips, highest dry matter losses (up to 10%) occurred already in P2 in presence of high thermotolerant mould content levels (up to 6.2 lgCFU g−1). In order to store larger chips or chopped pieces with low dry matter losses, the process should be designed in such a way that the duration of P2 is minimised. A later harvest at higher outdoor temperatures in spring can also have a beneficial impact on reducing dry matter losses.

Impact of storage on energy performance of laricio pine wood chips: A case study in Italy

This study evaluated the influence of storage method on the physical and chemical properties of laricio pine wood chips for energy generation in the region of Basilicata, Italy. The storage of wood chips is a key factor in the wood fuel supply chain because it allows to compensate temporal differences between production and consumption stages. Experimental trials were performed analyzing three storage methods of wood chips: uncovered pile, under vapour-permeable and waterproof cover (PP sheet), and under waterproof PVC cover (PVC sheet). During six months of storage (from August 2016 to January 2017), only the wood chips pile covered under PP sheet registered a decrease in moisture content (about -19%). Use of cover made of vapour-permeable material was also found to improve the heating value of biomass (about +15%). However, the ash content was observed to increase throughout the storage period, reaching the maximum value for the uncovered wood chips pile (about +74%). No statistically significant differences between PP and PVC sheets were detected for dry matter losses, while significant energy losses were found in every kind of storage system. As a result of the analyzed weather conditions, open-air uncovered storage is suitable for short-term storage periods (less than 2 months), while for long-term period the use of permeable covers is more profitable.

The Effects of Wood Storage on the Chemical Composition and Indigenous Microflora of Eucalyptus species Used in the Pulping Industry

Lipophilic extractives naturally occurring in wood tend to coalesce during pulping to form pitch deposits, which have particularly undesirable effects on the pulping process and quality of pulp produced. A chemical characterization of different eucalypt species [Eucalyptus nitens, E. grandis, and E. dunnii (of different site qualities)] wood and generated pulp was performed. This study aimed at determining the effects of wood storage at -20 °C (for 6 months), by examining their chemical composition and indigenous microflora. Fatty acids were the main lipophilic compounds among E. dunnii (SQ3 and SQ4) and E. grandis wood extractives. The wood of E. nitens posed the least risk for pitch deposit formation, making it the most suitable Eucalyptus species for pulping. Storage of wood chips at -20 °C had a similar effect as the traditional method of seasoning (storage of wood outdoors prior to pulping) used for the reduction of lipophilic extractives. A 25 to 44% reduction of total extractives was observed in the raw material after storage. Variations in bacterial and fungal communities were observed after storage, and should be taken into consideration when conducting lab scale trials. If storage of wood chips is necessary for lab testing, it should be retained for a maximum of 3 months at -20 °C.

Biological Risks from Long-Term Storage of Wood Chips

Biological Risks from Long-Term Storage of Wood Chips