The paper presents the process of electricity and thermal energy production in a cogeneration plant and the process of wood pellet production. The aim of this study was to analyze the energy ...gain—EROI for energy products that are created as a product contained in electrical and thermal energy and the energy contained in wood pellets. According to the obtained results, the production of only electrical energy from wood biomass in a cogeneration plant was not sustainable from an energy point of view, since the obtained electrical energy was only 1.46 times greater than the input wood energy (EROIel = 1.46), while the obtained energy of the produced wood pellets was 4.82 (EROIpel = 4.82). According to the results of equivalent carbon emission, positive net value was achieved only with cogeneration plant and pellet plant working in synergy. Wood is a renewable source of energy, and its economic use can create a significant energy gain. However, due to the trend of using renewable energy sources and the increasing need for electricity, such a process of obtaining electricity is financially profitable, although it is not justified from the energy profitability and environmental sustainability point of view.
Motor-manual work with a chainsaw is still an irreplaceable occupational activity in forest harvesting operations in Croatia and in many other countries. Chainsaw workers are exposed to different ...risk factors, such as noise and vibrations, heavy load lifting, awkward and preflexion postures, repetitive movements, etc. The working posture and the assessment of the center of mass plays an important role in understanding the exposure of forest workers to postural and occupational risks, either as a part of the entire work process or as a part of an individual element of the work technique. Therefore, the aim of this research was to investigate the impact of three different chainsaw starting methods (from the ground, between the knees, and “drop starting”) on the postural load of the chainsaw worker and its association with personal and occupational factors. The field portion of data collection was conducted in the second and third quarters of 2022. For trunk posture assessment (n = 74), the rapid entire body assessment (REBA) tool was used, and for the center of mass measurement (n = 28), the Xsens MVN Link motion capture suit was used, a relatively new technology that allows data collection in real field conditions. Descriptive and inferential statistical methods were used to verify and analyze the field data. Based on the obtained results, almost 50% of the sampled chainsaw workers ignored safety instructions and preferred “drop starting” a chainsaw. The results also showed that there is a significant difference between the three starting methods in the REBA score, as well as in the number of segments scored during the assessment. The obtained mean REBA score for all three methods is between 4 and 7, placing all methods at a medium level of MSD risk. Regarding the analysis of the Center of Mass (CoM) vertical deviation, the statistical difference is noticeable for the body mass index (BMI) group, the group related to experience with the chainsaw, and the age and height group in relation to three methods for starting a chainsaw. The safest method, which implies starting a chainsaw from the ground, resulted also as the riskiest in terms of postural strain, which, cumulatively over the time variable, can contribute to health problems in forest workers. In conclusion, related to the future process of professional training development for chainsaw workers, an integral part of the training must contain the most optimal postural-movement habits that need to be defined by further kinematic research in forestry.
Abstract Forest cleaning, being an operation that requires investment, but the return on investment is due for the next generations, utilizes tools and methods that mostly haven’t been humanized. ...Harmful vibration is still present in today’s forestry operations, and new tools provide possible reduction of exposure to vibrations. Petrol chainsaw and battery chainsaw (late cleaning) and billhook, machete, and battery shears (early cleaning) were used and observed in this study. Vibration levels were measured and assessed using validated Brüel & Kjær 4447 vibrometer which complies with the ISO 8041:2017 standard. The measurement was performed according to the recommendations of ISO 5349-1:2001 and ISO 5349-2:2001 standards. Vibration exposure was assesed using work sampling method on the obtained video recordings in order to calculate relative shares of different work elements. Results show that hand tools (machete and billhook) are causing the highest vibration levels, while battery shears cause the lowest. Battery chainsaw causes higher vibration levels while cutting, but lower daily vibration exposure than petrol chainsaw. A detailed revision in the classification of tools is needed, considering their ability to produce and transmit harmful vibrations to the operator. Using the current classification, the daily exposure to vibration of workers in early forest cleaning is high above legislative values.
The Ordinance on Occupational Safety and Health in Forestry proposes no more than 4 h of effective chainsaw work daily, while EU Directive 2002/44/EC proposes an EAV of 2.5 m/s2, and an ELV of 5 ...m/s2. The aim of this paper was to compare and assess the viability of the proposed restrictions. A case study in Croatia including 91 felled and processed trees, a detailed time study, and vibration magnitude measuring on European beech wet wood in compliance with ISO 5349-1:2001 and ISO 5349-2:2001 standards were performed. The results implied that tree species, processing method, and DBH have no influence on the time structure of working hours. Using bigger and more powerful chainsaws resulted in higher A(8) values; it was also noted that the right hand is more exposed. On average, none of the observed chainsaws exceeded 5 m/s2 of A(8). It can be concluded that state legislature, which allows a maximum of 4 h of chainsaw work a day, is appropriately protecting chainsaw workers from vibration exposure, but is also obsolete (1986) as it only uses the time limit. In contrast, European legislature requires a methodical approach to A(8) calculation and leaves room for individual evaluation of specific chainsaw work, which opens up possibilities of extending or shortening some chainsaw operations.
Compiling the research on forestry ergonomics, which is still a marginal field in terms of the sheer volume of published forestry-related articles, gives a good foundation and guidance for future ...research and publishing. This review aims to compile, classify, and analyze forestry ergonomics publications in JIF (Journal Impact Factor) journals regarding their spatial and temporal distribution, observed operations, machines and tools, and risk factors. A reference period from 2014 to 2023 was observed in this study. The Web of Science Core Collection database was used to filter publications in the field of forestry and ergonomics. A total number of 102 articles were selected. After selection, data regarding publishing year, journal name, main field, country of origin, forest operation, machine/tool, and risk factor were noted. The number of articles is ever-increasing with the last four years having above average numbers of articles. Countries from Europe and South America (Brazil) have the most publications. Most of the journals are ranked in the top 50%. Harvesting, wood extraction, and pre-harvesting operations have the highest number of records. Chainsaw, skidder, and pre-harvesting tools are the most observed means of work. The risk factors with the highest percentage of records are workload (23%), noise (20%), vibration (20%), postural load (16%), and MSD (Musculoskeletal Disorder) occurrence (7%).
The paper deals with the characteristics of three different types of power train hybridization of forest logging machines and with the benefits of reducing environmental impacts by comparing new ...technology with more conventional, older technology. New hybridization options that could be implemented in forestry machines are also discussed. The paper divides a hybrid solution into three classes based on the energy used in the system of hybridization. First is an electro-hybrid system that uses an electric motor and battery or different storage device. The second, a hydraulic hybrid system, is a solution with a hydraulic accumulator, hydraulic motor, and pump. The third system is a combination of the electro-hybrid and hydraulic-hybrid system. The current technical and technological development of hybrid drive systems, as well as their components, has led to significant improvements in drive performance and thus better performance of the new generation of forest vehicles. Improved energy efficiency using hybrid propulsion systems in forest vehicles would result in a significant reduction in greenhouse gas emissions and possibly lower maintenance costs.
Vibration Levels of Used Chainsaws Landekić, Matija; Bačić, Marin; Pandur, Zdravko ...
Forests,
02/2020, Letnik:
11, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Although professional chainsaws have come a long way regarding technical and ergonomic development since first introduced into forestry, they still remain a high-risk tool that can cause serious ...health problems. In this research, three types of used professional chainsaws were observed regarding harmful vibrations they emit and possible connection to years in use, chainsaw type, characteristics and level of vibrations. Measurements were performed in accordance with the recommendations of ISO 5349:2001. For the measurements, a measuring chain consisting of a triaxial accelerometer manufactured by Bruel & Kjaer and a vibrometer of the same manufacturer Type 4447. To evaluate the emitted vibrations, a daily exposure value A(8) was used. Exposure durations to predefined working operations were identical for every used chainsaw to enable the possibility of equal comparability. Obtained results indicate that the daily vibration exposure A(8) is not affected by the years in use of the chainsaw. Results also show that the power and chainsaw type have an influence on daily vibration exposure. The recommendation for the praxis is to use even lighter and smaller chainsaw wherever is possible.
The application of various graphic analytical software solutions in the research aimed at designing and determining the ergonomic and biomechanical harmony between forestry workers’ anthropometric ...measures and their working positions and movements is still scientifically incomplete and largely unexplored in forestry, especially regarding motor manual work with chainsaws. Accordingly, the aim of this research is to numerically represent the general kinematic model of forestry workers’ upper body while starting a chainsaw. The same is determined by using a state-of-the-art motion capture suit with inertial measurement units (IMUs). An additional research aim is to investigate numerical values of the forestry worker kinematic model against the three potentially applicable methods of starting a chainsaw and work experience with a chainsaw. Field data collection was carried out during the spring and summer of 2022 and 2023, and a total of 51 chainsaw workers were sampled in different relief areas. The results of the subject research show that none of the observed methods of starting a chainsaw are entirely safe for the worker, concerning the aspect of MSD development, if the body movements within the working element are performed in an incorrect way. From safety and kinematic aspects, regarding forestry workers’ upper body values, the most neutral work posture (N-pose) is when a worker is using the “between the knees” method. The method “from the ground” can be used as secondary option if the workers are educated in taking the correct position of the upper body, i.e., to practice the rule of hip hinge. With the aim of extending the working ability and working life of forestry workers, interdisciplinary cooperation between occupational medicine, kinesiologists, and forestry experts is needed to create a guide of statodynamic efforts and correct postural movement habits during motor manual work in logging operations.
Professionally trained, motivated, and responsible forestry workers are a fundamental prerequisite of successful forest production and an integral part of the modern, generally accepted paradigm of ...sustainable forest management. However, the forestry sector today is increasingly facing the problem of a shortage of forestry workers and the challenge of obtaining a qualified and sustainable workforce. This paper, therefore, presents the reflections of forestry workers on the challenges and future perspectives on their profession and forest work. The findings of the examination of forestry workers in Bosnia and Herzegovina include some general characteristics of forest work and indicators of the state and position of forestry workers (socio-demographic characteristics, attitudes toward work, profession, etc.). Specially addressed are some problems and challenges faced by the forestry sector in obtaining and recruiting the necessary workforce—the severity of the forestry worker shortage, the main causes and reasons for the lack of workers, factors for stronger recruitment and retention of workers, work commitment, sustainability of the workforce, future perspectives on forestry work, etc. The differences between workers employed in public and private forestry companies were examined. The survey included 268 respondents and was carried out in the second half of 2021. The purpose of the work was in sensibilizing the profession and the public to the issues of the workforce in forestry, its position, and reflections, and in providing the basis that can be an important contribution toward improving the condition and sustainability of the forestry workforce.
The aim of this research is to measure the energy consumption and compare the cutting performance of three types of battery-powered chainsaws (Stihl MSA 200, Stihl MSA 220, and Stihl MSA 300). Tested ...chainsaws were powered by two different battery packs (Stihl AP 300 S and Stihl AP 500 S) with different energy capacity and output current when cutting two wooden beams, European beech (Fagus sylvatica L.) and black locust (Robinia pseudoacacia L.) with different densities and moisture content. Energy consumption was measured using a multimeter built-in battery charger housing, and consumed energy was noted in watt-hours. Each individual cut was recorded with an action camera at 60 frames per second, and the duration of the cuts recorded in centiseconds was observed on the obtained recordings. Results show significant differences in energy consumption and cutting duration between individual chainsaw/battery combinations. Energy consumption ranged from 2.45 to 4.50 Wh per cut for beech (Stihl MSA300E_AP500S and Stihl MSA220_AP300S, respectively) and from 3.10 to 5.00 Wh per cut for black locust (Stihl MSA300M_AP500S and Stihl MSA220_AP500S, respectively). Duration of the cut ranged from 3.48 to 9.24 s per cut for beech (Stihl MSA300M/H_AP500S and Stihl MSA220_AP300S, respectively) and from 3.74 to 9.35 s per cut for the black locust (Stihl MSA300M_AP500S and Stihl MSA220_AP300S, respectively). In general, it can be concluded that more powerful chainsaw/battery combinations (Stihl MSA300_AP500S) consumed less energy per cut and had better cutting performance (shorter cut). In that regard, more powerful chainsaws had greater cutting efficiency, i.e., more cuts on one charge (battery) but shorter cutting time on one charge. The effect of tree species (fresh-sawed beech/air-dried black locust) on energy consumption and cutting performance is absent on the most powerful chainsaw/battery combinations. Today, lithium-ion batteries still have 70 times less energy density than petrol. However, if there is a significant increase in the energy density of the batteries in the coming times, battery chainsaws will most certainly displace petrol chainsaws from use in the future.
PDF