Wood Pellet Production Research Articles

A process for producing lignin and volatile compounds from hydrolysis liquor

BackgroundHot water hydrolysis process is commercially applied for treating wood chips prior to pulping or wood pellet production, while it produces hydrolysis liquor as a by-product. Since the hydrolysis liquor is dilute, the production of value-added materials from it would be challenging.ResultsIn this study, acidification was proposed as a viable method to extract (1) furfural and acetic acid from hot water hydrolysis liquor and (2) lignin compounds from the liquor. The thermal properties of the precipitates made from the acidification of hydrolysis liquor confirmed the volatile characteristics of precipitates. Membrane dialysis was effective in removing inorganic salts associated with lignin compounds. The purified lignin compounds had a glass transition temperature (Tg) of 180–190 °C, and were thermally stable.ConclusionsThe results confirmed that lignin compounds present in hot water hydrolysis liquor had different characteristics. The acidification of hydrolysis liquor primarily removed the volatile compounds from hydrolysis liquor. Based on these results, a process for producing purified lignin and precipitates of volatile compounds was proposed.

Energy consumption and equivalent emission of CO2 at wood pellets production in Serbia

The paper is analyzing wood pellets production from forest to end user, respectively, from breeding, protection, management, maintenance, and regeneration of forests to gate of end user in case of Serbia. Analysis includes all kind of input materials, energies, and equivalent emissions of CO2 in wood pellets production. The results obtained are: specific energy consumption (heat and electricity) was 2,419 kWh/tpellet, equivalent emission of CO2 was 293 kgCO2/tpellet and the relationship between the net calorific value of wood pellets and the total input energy for their production and transport (EROI) was 1.9. The results were compared with those in world factories and based on that certain conclusions and recommendations are given. Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 43007: Studying climate change and its influence on the environment: impacts, adaptation and mitigation]

The logging waste as inexhaustible resource for alternative energy

The article shows that during the production and consumption of fuel wood for bioenergy projects in the organization of the Northwest and other regions of Russia there is the problem of lack of raw materials. It is established that the waste timber, during cutting on average, about 20% of the stock of standing timber. This value varies according to region, type forest resources and the skills, and technical equipment performer. Therefore, the main purpose of the article is a system evaluation of the use of forest residues in Russia. The authors present data on volumes of raw materials for production of wood chips and pellets on example, the Northwest region of Russia. Only about 30% of wood chips are now received from wood waste, bulk wood chips, and pellets produced from the wood of stems. Small volume of use of bark, twigs, branches, tops, stumps, and roots is due imperfection of processing technologies. Another important issue addressed in the article ? the lack of standards and guides taxation inventory valuation and structure of the waste in many regions of Russia. This primarily relates to the hardwood. Research has shown that, depending on tree species, the structure and volume of waste are significantly different. Expert evaluation conducted by the authors shows that the proportion of forest residues from 5 to 20% of the stock of wood. It is found that in different forest types share twigs, branches, stumps, and roots vary considerably according to species of tree. But even within the forest reserves such as twigs, branches, and underground parts of the same species depend strongly on the age of stands and their completeness, and the differences may reach 2 to 5 times the size.

Analytical inventory of process variables for sustainable development of a small business for integrated production of wood pellets

The paper presents some theoretical considerations and the related deliverable results obtained within a research approach developed for analytically inventorying the process variables for a wood pellets micro-production activity integrated with self-providing crops of energetic willow. The study is part of a larger research approach intended to accurately define the appropriate specifications for developing a sustainable small business in this area. Within the particular research approach being discussed in the paper, some conceptual models have been structured and are proposed, based on process systematic analysis, as following: a model of the research general hypotheses; a model of the general conceptual research frame; a process flow model for the considered integrated processes, respectively wood pellets micro-production and energetic willow crops; a model for sustainability groups of indicators to be considered; two models for process variables inventorying and classification, one for each of the two considered integrated processes. After the research hypotheses are simplified by considering some particular implementing conditions, a final model of the investigated variables is submitted to discussion. Some adequate conclusions revealed by the research approach, together with some directions of further research development are finally identified and presented in the paper.

A survey analysis of the wood pellet industry in Finland: Future perspectives

Finland has the greatest forest cover of European countries and thus considerable raw material potential for wood pellet market development. Wood pellet production and consumption volumes in the country have increased steadily during the last decades. The aim of this paper is to present an overview of the current status of the Finnish wood pellet business and discuss the main opportunities and challenges facing future development of the industry. The paper collects and revises data on the Finnish wood pellet market based on the results of a survey of nearly 60 wood pellet experts. The results show that neglect of policy support and a lack of suitable regulation are the key factors inhibiting Finnish wood pellet industry development. Currently, wood pellets are not economically competitive with other fuels. However, Finnish wood pellet markets seem promising if challenges such as high raw material costs and competitiveness with other fuels, especially for household users, are addressed. The country has the potential to become a more important producer and consumer on European wood pellet markets if effective policy support and a suitable regulatory framework are formulated.

Energy Management in Wood Pellets Production

The objective of Directive 2012/27/EU of the European Parliament and Council on energy efficiency is to reach 20% energy efficiency increase by 2020; in order to achieve that, solutions must be found on how to efficiently use energy by reducing energy losses and at the same time not affecting its efficiency. The main goal of the energy management model is to increase the volume of produce depending on energy consumption. There are different and also similar models in the world that have been developed and introduced with the aim to improve energy management systems in different sectors. Several sectors may use one particular management model that has been adapted to the sector‘s specificities. The developed model provides information and helps to evaluate the operation of pellets production unit and the possibilities for improvement. Management model with the respective indicators of the wood pellets production unit have been integrated in this model. Evaluation of indicators has been based on the energy flows of particular production units and their influence on the produce. The introduction and evaluation of such model in a production unit allows to better determine the optimization of production stages and energy consumption. The model has been tested with the data provided by concrete production units about changes in indicators depending on their mutual correlation and production processes in general. Introduction of such energy management systems will facilitate the optimization of energy consumption, which directly influences and allows evaluation of the produce.

Locational determinants for wood pellet plants: A review and case study of North and South America

The European Union’s Renewable Energy Directive has led many electricity producers in Europe to use wood pellets in place of fossil fuels. North America has become one of the primary suppliers of wood pellets to Europe. This paper critically examines literature, economic models and data, as well as the supply chain and country risk factors, related to wood pellet production to anticipate where North and South American pellet mills should be built to meet Europe’s demand. Canada, the United States, and Brazil maintain the largest natural forest area, planted forest area, and industrial roundwood production; however, South American countries achieve faster plantation growth rates. The World Bank’s Logistic Procurement Index and IHS’s Country Risk Index were used to score and rank countries’ investment climates, based on their supply chain and risk factors. In this regard, the United States, Canada, and Chile performed best, in contrast to Venezuela, Bolivia, and Ecuador. When considering both wood supply and investment climates, the United States, Canada, and Chile were the most attractive countries to build a pellet mill, while countries, such as Argentina, Brazil, Colombia, Paraguay, and Peru present significant trade-offs between having significant wood resources and riskier investment climates.

Model calculations on the use of mobile and stationary units for wood pellet production

This paper presents the model calculations made for supporting the decision making of different technology alternatives. Base cases were A) use of a mobile pelletizer and B) using pellet factories at fixed locations for the production of a new product, sheep wool pellets. Calculations were made for three alternatives for each base case. The results of the model were used to examine the energy, time and cost criteria of the alternatives. Based on the given preliminaries, results of the model calculations supported the recommendation to choose case B) for further technology management and supply chain management decisions.

Model calculations on the use of mobile and stationary units for wood pellet production

This paper presents the model calculations made for supporting the decision making of different technology alternatives. Base cases were A) use of a mobile pelletizer and B) using pellet factories at fixed locations for the production of a new product, sheep wool pellets. Calculations were made for three alternatives for each base case. The results of the model were used to examine the energy, time and cost criteria of the alternatives. Based on the given preliminaries, results of the model calculations supported the recommendation to choose case B) for further technology management and supply chain management decisions.

Costs of Wood Pellet Production in Iran

Climate changes and increased Earth’s temperature form a phenomenon that affects all humans and countries. Consequently, even countries with plenty of fuel energy resources have realized the importance of this issue. Wood pellet is among the most commonly used bio fuels and is spreading quickly all over the globe. In this research, the feasibility of wood pellet production in Iran was assessed by studying a production project and economically analyzing it. Based on the results, all of the economic indicates are reflective of economic utility of wood pellet production in Iran. For instance, the IRR index of the project was 64.54%, and the final price of the product was 118.89 EUR per ton. Analysis of production costs indicated that raw materials had the highest share of the final price followed by fixed investment costs and energy costs.

Impact of wood pellets export on the development of their production in Serbia with the effects of substituting enegry from fossil fuels and reduction of carbon dioxide emission

The paper presents the results of researching the impact of export on the production of wood pellets as well as the situation on the market for this wood fuel in Serbia. Objective of the research was to produce scientifically and professionally founded conclusions and the related adequate recommendations to the decision makers in order to improve the situation on wood pellets market in Serbia and eliminate the existing problems which significantly burden and slow down this development. Special objective of the research was to observe the contributions of wood pellets to the mitigation of climate changes using Serbia as the example. Results of the conducted research show that the expansion of the consumption (demand) increase in the European Union countries in the last fifteen years and the related increase of export from Serbia are the most significant factors which have influenced the development of wood pellets production in Serbia. Parameters of econometric model of the impact of export on the increase of production show that production increase of 1.17% can be expected with the increase of export of 1%. Thus, the number of wood pellet producers has rapidly increased in the last ten years, from 2 producers in 2006 to 52 active producers in 2016. Increase of the number of producers was also accompanied by the increase of the installed capacities. At the end of 2015, total installed capacities for wood pellet production in Serbia reached 550 thousand tons, and the realized production was 229 thousand tons, or 41.6% of the installed capacity. Consumption of wood pellets in Serbia in the last four years achieved significant increase and reached the level of 89 thousand tons in 2015. However, concerning the segment of wood pellets consumption in Serbia, the situation is still unsatisfactory despite the fact that the consumption has been increasing year after year. Average price of 1 kWh of energy from wood pellets exported from Serbia was in the range 20-44 ?$, which is 2.1 to 3.2 times less than the price of 1 kWh of energy from the natural gas which was imported in Serbia in the observed period.

Sustainable logistics network for wood flow considering cascade utilisation

To address the growing demand for wood as a renewable resource, a trend that has arisen in recent years is to follow the principle of cascade utilisation and to use wood residues from by-products. The cascading principle represents a method supporting resource efficiency through the sequential use of the remaining quality resources from previous commodities and substances. The logistics concept deserves special attention with respect to the utilisation of wood resources and the cascading principle as logistics processes constitute the largest share of costs.This work considers a logistics network for wood flow for different products in various sectors. Examples include a logistics network for particle board in the material-based sector, pulp and paper production in the chemical sector, and wood pellets production in the energy sector using cascade utilisation and recovered wood. A transportation problem is modelled using a mixed-integer linear programming (MILP) model, and it is applied to a case study in Lower Saxony using the software CPLEX v12.5. The aim is to minimise the total logistics costs of a logistics network, including those associated with harvesting, chipping, storage and transportation, for several companies in different sectors. UMBERTO, a life cycle assessment (LCA) software, is used to investigate the potential environmental impacts of the optimised logistics network. The approach is applied to three scenarios in Lower Saxony, a state in Germany. The initial results indicate that the total cost of the considered wood logistics network does not change significantly for the cascading scenarios in comparison to that associated with fresh wood, but there would be a substantial reduction in CO2 emissions if cascade utilisation is used in the logistics network.

Effects of Moisture Content and Particle Size of Sawdust and Operating Time of Flat-die Pelletizer on the Fuel Characteristics of Wood Pellets Fabricated with Mongolian Oak and Rigida Pine Sawdust

This study was conducted to investigate the effects of a number of factors (moisture content and particle size of sawdust and operating time of flat-die pelletizer) on the fuel characteristics of wood pellets fabricated from Mongolian oak (MOK) and pitch pine (PCP) sawdust. MOK and PCP pellets were produced from sawdust of varying moisture content (8, 10, 12%) and was screened to mesh sizes of 2 and 4 (0.64 and 1.27 mm). Moisture content (MC), bulk density (BD) and durability (DU) of the produced pellets were also determined based on the operating time of the flat-die pelletizer (10, 20, 30, 40, 50 And 60 min). The MC of both MOK and PCP pelletswere not altered based on their duration in the flat-die pelletizer. However, the BD and DU of MOK pellets were higher than those of PCP pellets. Increasing the MC of the sawdust resulted in an increase in pellet MC and BD, reducing their fuel value. The BD of PCP pellets was greatly decreased when sawdust with a MC of 12% was applied. The DU of both MOK and PCP pellets increased when the MC was increased from 8% to 10%. However, no further increase in DU occurred through the use of MOK sawdust with a MC of 12%, and the DU of PCP pellets was reduced through the use of a MC of 12%. Pellet MC, BD and DU were not influenced by the particle size of sawdust, or by the operating time of flat-die pelletizer. On the other hand, BD and DU of MOK and PCP pellets were lower than those of Larch pellets which, having very suitable characteristics, were used as a reference pellet in this study. In conclusion, MOK pellets with suitable fuel characteristics, satisfying the minimum requirement of the 1st-grade pellet standard designated by the Korea Forest Research Institute, were produced. However, the BD and DU of PCP pellets were lower than the standard, and especially, the DU of PCP pellets produced with the sawdust MC of 12% was inferior to the standard for 4th-grade pellets (?95.0%). Based on the results, 10% MC for MOK sawdust might beoptimal for the production of MOK pellets, but PCP alone is not suitable as a raw material for the production of wood pellets under the experimental conditions examined in this study.

Sustainable biomass supply chains from salvage logging of fire-killed stands: A case study for wood pellet production in eastern Canada

Abstract While western Canada is an international leader in the growing pellet market, eastern Canada remains a minor player despite its abundance of wood residues from natural disturbances. This study investigates the potential amount of biomass from salvage logging of fire-killed stands along with harvesting residues from clearcut to supply pellet plants in eastern Canada between. We built and optimized supply scenarios in two forest management units to fulfill different pellet plant capacities under various operational, ecological, and economics constraints. Despite the high spatial and temporal variability of burned area, this study confirms the large quantities of biomass from fire-killed stands available as ecologically sustainable feedstock for bioenergy, which, combined with the comparatively smaller and more stable quantities from clearcut harvesting residues could supply theoretical pellet plants. Our results show that under current market conditions, biomass both from harvest residues and fire-killed stands could fulfill on average between 5% and 66% of a 50 000 ODT y−1 plant needs at a price of $90 ODT−1 of wood chips for the decade considered. With a wood chip price at $120 ODT−1, 100% of the production capacity of a 50 000 ODT y−1 plant or even of a 100 000 ODT y−1 plant could be met. Ecological constraints related to the need to protect sensitive sites and prevent recovery operations on them, and operational constraints related to the capacity of the machinery to recover biomass from a given site, have little impact on the supply of biomass from fire-killed stands. However, important regional variations exist in terms of potentials and constraints, which would need to be taken into account when designing bioenergy industrial networks.

Development of wood pellets market in South East Europe

The paper presents the results of researching wood pellets market in nine countries in South East Europe and Slovakia. Objective of the research was to observe the actual situation regarding the number of producers, size of installed capacities, production volume, foreign trade flows and existing problems and obstacles which significantly limit the sustainable development of wood pellets market in the selected countries. Selection of such an objective results from the fact that according to the stated elements there are no sufficiently reliable data, wherefore this region is a huge gap in numerous reports of international and national organizations and institutions. Results of the conducted research show that in the middle of 2014, 245 producers were engaged in wood pellets production in South East Europe and Slovakia, 116 of which were located in Bulgaria and Serbia. Most of the producers of wood pellets has installed capacities of 1,000-5,000 tons annually, while only 18 factories in the entire region have the installed capacity over 30,000 tons/year. Observed collectively in all stated countries, the total installed capacities for wood pellets production were 2.2 million tons in 2013 and the realized production was 1.36 million tons. The largest part of the produced amounts of wood pellets in this region is exported. 1.06 million tons were exported from the region in 2013, which is 77.9% of the realized production. Such high export is the result of the underdevelopment of the local market (Slovenia is the only exception) and the problems which exist and limit its faster development in most countries.

Upgraded Pellet Making by Torrefaction—Torrefaction of Japanese Wood Pellets

Upgraded wood pellets were produced and evaluated by torrefaction of wood pellets. In this study, conventional wood pellets were initially prepared and subsequently torrefied on a laboratory and then larger scale. During the laboratory scale production, pellets from wooden parts of Japanese cedar (sugi, Cryptomeria japonica) and Japanese oak (konara, Quercus serrata) trees were heat- treated in an inert gas oven under nitrogen atmosphere around 170°C - 320°C. For the Japanese cedar, the calorific values were improved by heat treatment up to 260°C. By heat treatment at 240°C, the upgrade ratio of higher heating value (HHV) was nearly 30% and the energy yield was 97%. For the Japanese oak, the calorific values were improved by heat treatment up to 320°C. By heat treatment at 280°C, the upgrade ratio of HHV exceeded 30% and the energy yield was 84%. On a larger scale, a conventional charcoal oven was modified for torrefied wood pellet production, meaning that torrefied wood pellet with 25 MJ/kg of calorific value was produced during heat treatment at 350°C. A mixture of conventional and torrefied pellets was applied to a commercial pellet stove, and torrefied wood pellets produced in this study might be usable as fuel for conventional pellet stoves.

Economics of co-firing coal and biomass: An application to Western Canada

Co-firing biomass and coal in retrofitted power plants is an efficient means to reduce carbon dioxide emissions in the energy sector. Under IPCC reporting rules, the impacts of energy produced from biomass would not be reported in the energy sector, thereby effectively lowering the emission intensity of a power plant. In this study, a carbon tax is compared to a feed-in tariff for incentivizing conversion of coal plants to co-fire with biomass. In the application, a model of the Alberta electrical grid with an intertie to British Columbia is linked to a fiber transportation model for these provinces. Results indicate that there is an upper threshold on a carbon tax after which retrofitting of coal plants is less efficient than increasing natural gas generating capacity. This is not the case with a feed-in tariff as it specifically targets biomass energy. Although the optimal generating mix achieved with a carbon tax leads to lower aggregate emissions than the mix achieved using a feed-in tariff, it will result in higher average generating costs. Results indicate that it is optimal for Alberta to retrofit approximately 500MW of current coal capacity (8.6%) to co-fire with biomass, although Alberta wood pellet production acts as a constraint on further conversions.

Comparative cradle-to-gate life cycle assessment of wood pellet production with torrefaction

Torrefaction is a thermal pre-treatment process for upgrading raw biomass into a more energy dense fuel. Torrefied biomass is combined with a densification process to increase its bulk density similar to conventional wood-pelleting production. This paper identifies the significant environmental impacts associated with production and delivery of these two fuels, using cradle-to-gate life cycle assessment. A feedstock of Scots Pine is modelled for a localised torrefaction/wood pellet plant located in Norway, with the products from each facility delivered to a power station in the UK.Results show that the relative benefits of torrefaction over wood-pellets are higher on per MJ delivered basis due to the higher calorific value of the fuel. The climate change and fossil depletion impacts for torrefied pellets modelled were lower than wood pellets, using an assumption that the drying requirement of the reactor was 3.0MJ/kg water removed for both cases. Sensitivity analysis of the model indicated that the relative impact improvement of the torrefied pellet case compared to wood pellets is strongly dependent on the biomass drying requirement and the proportion of total process heat supplied by the re-circulated torrefaction gas. Land requirements for torrefied pellets are higher due to the mass losses in production.

Net environmental impacts of low-share wood pellet co-combustion in an existing coal-fired CHP (combined heat and power) production in Helsinki, Finland

The EU's energy sector depends heavily on fossil fuels, which contribute to climate change. This is why climate mitigation targets for energy production have been set, including an increased biomass use requirement. In Finland, biomass is commonly utilised but its capital, Helsinki, is still dependent on fossil fuels. With the ambition of becoming climate neutral by 2050, Helsinki is testing, inter alia, low-share wood pellet and coal co-combustion in a CHP (combined heat and power) plant.The objectives of this paper were to assess the net environmental impacts of the co-combustion and changes in urban air quality connected to pellet transport, and to identify environmental hotspots relevant to possible future higher-share co-combustion. The applied methods were screening LCA (life cycle assessment) and fine particle dispersion modelling.The results prove that low-share wood pellet co-combustion in CHP production leads to net environmental impact reductions and does not deteriorate air quality in the urban environment. If higher-share co-combustion were to be implemented, the environmental hotspots to focus on would be the operational issues of a power plant and the origin and sustainability aspects of wood pellet production.

The economic potential of wood pellet production from alternative, low-value wood sources in the southeast of the U.S.

The global demand for wood pellets used for energy purposes is growing. Therefore, increased amounts of wood pellets are produced from primary forestry products, such as pulp wood. The present analysis demonstrates that substantial amounts of alternative, low-value wood resources are available that could be processed into wood pellets. For three resources, test batches have been produced and tested to qualify for industrial pellet standards. These include: primary forestry residues from premerchantable thinning operations, secondary forestry residues from pole mills and post-consumer wood wastes from discarded wooden transport pallets. The total wood potential of these resources in the southeast of the U.S. (Florida, Georgia, North Carolina, South Carolina), was estimated to be 1.9 Tg y−1 (dry) available at roadside (excluding transport cost) for 22 $ Mg−1 (dry) increasing to over 5.1 Tg y−1 at 33 $ Mg−1 (dry). In theory, 4.1 Tg y−1 pellets could be produced from the estimated potential. However, due to the geographically dispersed supply of these resources, the cost of feedstock supply at a pellet plant increases rapidly at larger plants. It is therefore not expected that the total potential can be processed into wood pellets at costs competitive with those of conventional wood pellets. The optimal size of a pellet plant was estimated at between 55 Gg y−1 and 315 Gg y−1 pellets depending on the location and feedstock supply assumptions. At these locations and plant sizes, pellets could be produced at competitive costs of between 82 $ Mg−1 and 100 $ Mg−1 pellets.