The Missing Limb: Including Impacts of Biomass Extraction on Forest Carbon Stocks in GHG Balances of Wood Use

The global carbon neutrality challenge places a spotlight on forests as carbon sinks. However, greenhouse gas (GHG) balances of wood for material and energy use often reveal GHG emission savings in comparison with a non-wood reference. Is it thus better to increase wood production and use, or to conserve and expand the carbon stock in forests? GHG balances of wood products mostly ignore the dynamics of carbon storage in forests, which can be expressed as the carbon storage balance in forests (CSBF). For Germany, a CSBF of 0.25 to 1.15 t CO2/m³ wood can be assumed. When the CSBF is integrated into the GHG balance, GHG mitigation substantially deteriorates and wood products may even turn into a GHG source, e.g. in the case of energy wood. Here, building up the forest carbon sink would be the better option. We conclude that it is vital to include the CSBF in GHG balances of wood products if the wood is extracted from forests. Only then can GHG balances provide political decision-makers and stakeholders in the wood sector with a complete picture of GHG emissions.

Improving germination with pre-sowing technique on Caliandra calothyrsus Meissn

Red Calliandra (Caliandra colothyrus) is a high-quality energy wood raw material that can be produced rapidly. It’s ideal for making wood pellets. The need for wood pellets is on the increase globally. For the production of wood pellets continuity, sufficient materials were required, requiring the development of red calliandra cultivation. The long duration of the seed germination process due to the hard seed coat is an obstacle in the generative propagation of red calliandra. This study aimed to determine the best treatment for red calliandra dormancy breaking and simultaneous germination. A factorial fully randomized design (F-CRD) with two treatment factors was used in this study. The first factor is type of solution (P) with three levels consisting of: P1: soaking in water; P2 : immersion with MSG solution (12 grams/liter); P3 : immersion in young coconut water (100%). The second factor is the length of immersion time (T) with three levels consisting of: T1: soaking time for 8 hours; T2 : immersion time for 12 hours; T3 : immersion time for 16 hours. Each treatment consisted of 20 seeds, which were replicated three times for a total of 540 seeds. The initial day of germination, length of germination, percentage of germination, and germination rate index were all measured. The results showed that that the most optimal germination for red Calliandra found in the P1T1 treatment (soaking in water for 8 hours). It can be shown from all observed parameters

Profitability of the First Commercial Thinning, a Simulation Study in Northern Finland

Despite positive signals from increasing growing stock volumes and improved roundwood trade, first commercial thinnings (FCTs) tend to be a bottleneck in Finnish forest management and forestry. The reasons are many, but probably the most crucial would be the lack of simultaneous economic incentives for participating agents, i.e., private forest owners and forest machine contractors. This is due to poor stand characteristics in most FCT cases: low cutting removal with small average stem size. There are five predetermined management options: (1) Industrial wood thinning with only two timber assortments, pulpwood and saw logs, (2) Integrated procurement of industrial and energy wood, (3) Energy wood thinning solely consisting of delimbed stems, (4) Whole-tree energy wood thinning with an energy price of 3 € m−3 and (5) Whole-tree energy wood thinning with energy price of 8 € m−3, that were applied for six separate forest stands located in Northern Finland, and derived from a database representing stands with an urgent need for FCT. Then, a two-phase financial analysis consisting of stand-level optimization (private forest owners) and profitability assessment (contractor) was conducted in order to find out whether there would be simultaneous economic incentives for both participants of FCT. The stand-level optimization revealed the financially best management options for a private forest owner, and then, for a contractor, the profitability assessment exposed the profit (or loss) associated with the particular management option. In brief, our results demonstrated that conducting either an industrial wood thinning (1) or an integrated procurement (2) resulted in a positive economic incentive for both the private forest owner and the contractor in all six cases (stands). Further, applying energy wood thinning with delimbed stems (3) would even generate a financial loss for the contractor, given the roadside prices applied in this study

Variability of Normative Properties of Wood Chips and Implications to Quality Control

The research was conducted with the goal to determine the variability of the quality parameters of the wood chips produced from the most favorable raw material (energy roundwood), and in the most controllable operational conditions (pellet factory), as the first step in identifying opportunities to optimize the wood chips’ quality monitoring. Four raw material types were tested: fir/spruce and beech debarked energy roundwood, as well as energy wood with bark of the same species. Sampling was conducted during six consecutive months along with laboratory testing, all according to the HRN EN ISO standards for solid biofuels. Interpretation of the results was done in relation to deviation from the first sampling results (as an indicator of the possibility to retain the quality of wood chips), and repeatability and reproducibility set in the standards (as an indicator of acceptable variability). The influence of the species and debarking process on the wood chips’ quality was analyzed as well. Relative deviation from the first sampling as well as the quality class change pointed moisture content as a normative property with the lowest possibility to retain initial values over the six-month period. Ash content results indicated a strong possibility to maintain the initial ash content class in the majority of the samples. In just three cases, the results of ash content were outside the reproducibility limits with first sampling as a reference. Gross calorific value results pointed only four samples outside the reproducibility limits with the first sampling results are set as a reference. Wood species influenced gross calorific value and the median value of the particle size distribution and debarking showed a significant positive effect on the moisture content reduction as well as on the ash content reduction. Presented findings are indicative for the investigated raw materials, however for the general conclusion on the subject of wood chips normative properties variation, various raw material types will have to be examined in further research.

Energy wood production by disk cutting machines with different methods of chip emission

The article describes the methodology of physical and mathematical modeling of the mechanism for ejection of chips of a disk chipper. This technique allows you to calculate and optimize the design and technological parameters of the chip ejection mechanism. To accomplish this task, the flow of chip elements was divided into separate spherical elements, and the working surfaces of the chip ejection mechanism are represented by a set of fragments of planes conjugated to each other. When creating a mathematical model for calculating and optimizing the design and technological parameters of the chip ejection mechanism, the following indicators of the efficiency of the chip ejection mechanism were analyzed: the rate of chip ejection at the exit of the chipping line, the probability of chip ejection from the first revolution of the chipping disk, the mechanical power consumed for the ejection of chips after the stage of crushing the cut residues knives. The mathematical model is implemented in a computer program in the Object Pascal language in the Delphi 7 development environment. The program allows carrying out computer experiments to analyze the movement in the casing and chipping of chips obtained from felling residues and to study the effect of the design and technological parameters of the ejection mechanism on the efficiency of the disk chipper. The computer studies carried out made it possible to determine the best numerical ranges of the chipping disk rotation frequency and the number of blades located on the chipping disk. The likelihood of chip entrainment at the first revolution of the chipping disk and the power consumption for the ejection of chips from the disk chipper were also determined.

Analysis of Areas and Prospects for the Use of Agrobiomass for Energy Production in Ukraine

Purpose of the study is to assess the current and prospective energy potential of agribiomass (agricultural residues and energy crops) in Ukraine, to determine its main components and the most effective areas of their use. Methods. The assessment of the current potential of agribiomass is performed using official statistics on crop production in Ukraine. Based on these data, the total amount of crop residues formed and their share available for energy needs is determined. When assessing the potential of energy crops, it is assumed that they are grown on 2 million hectares of unused agricultural land, the total area of which is up to 4 million hectares in Ukraine. The study of the prospective potential of biomass is performed for 2050, based on key growth factors, such as increasing yield of crops, especially cereals; doubling the area under energy crops and increasing their yields, etc. Results of the assessment show that according to 2018 data, the total bioenergy potential in Ukraine is more than 23 Mtoe (the economic potential). Its largest components are agricultural residues (44%) and energy crops (32%). Expert estimates suggest that by 2050, the biomass potential could increase to more than 47.5 Mtoe/yr, in other words almost to double. Forecasting the structure and directions of use of biomass potential by 2050 shows that about 20 Mtoe of biomass/biofuels of the following types will be consumed for energy: wood biomass, primary and secondary agricultural residues, energy crops, biogas/biomethane from different types of raw materials, liquid biofuels (biodiesel, bioethanol). Conclusions. Areas of use of biomass/biofuels include the production of heat and electricity from solid biofuels, obtaining of biogas and biomethane, as well as the production of motor biofuels (biomethane, biodiesel, bioethanol). In the near future, it is considered necessary to develop a long-term strategy for the development of bioenergy in Ukraine, taking into account results of the study. In turn, the basic figures of the bioenergy development strategy can be used for the elaboration of the updated Energy Strategy of Ukraine until 2050.

REGULARITIES OF CONVECTIVE LOW TEMPERATURE DRYING OF ENERGY SPECIES WOOD

The article presents an analysis of the technological stages of the production of solid biofuel from energy wood species, it is noted that up to 70% of the total energy consumption is spent on drying processes in technological processes. The urgency and advantages of low-temperature drying of such wood have been substantiated. It is noted in the work that the heat and humidity modes should ensure an increase in the energy efficiency of the process and a high calorific value of the resulting fuel. The purpose of the article is to intensify the process of dehydration of energy wood to obtain solid biofuel, to determine the effect on the process of convective low-temperature drying of the operating parameters of the drying agent, the size and shape of the raw material, and the specific load on the drying surface. Energy willow was used as an object for dehydration, the initial moisture content of which varied over a wide range from 45 to 60% per wet weight; dehydration was carried out until the material reached residual moisture content of 5...6%. Studies on the effect of the temperature of the drying agent on the kinetics of moisture exchange prove that an increase in temperature from 80 to 100 °C intensifies heat and mass transfer and reduces the duration of the process by up to 25%. The results of experimental studies of the effect of the specific load on the dehydration process showed that an increase in load has a positive effect on the productivity of the drying unit and increases the volume of processed raw materials. At the same time, the total duration of dehydration from the minimum load to the maximum increases by 3.5 times. It is noted in the work that a significant parameter of influence on the kinetics of drying and increasing the efficiency of the process is the method of grinding the raw material. The most intensive mode corresponds to the method of grinding willow by combining abrasion and impact. With this method of grinding, the drying time is reduced from 15 to 25% in comparison with the others considered. The combination of the specified conditions and parameters of low-temperature drying provides an economical process and obtaining dried willow with low and evenly distributed residual moisture. The use of such material in the technological cycle of biofuel production guarantees the reliable operation of the combustion device for a long time.