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Environmental Impacts of Biofuel-Fired Small Boilers and Gasifiers
Published in Mateusz Szubel, Mariusz Filipowicz, Biomass in Small-Scale Energy Applications: Theory and Practice, 2019
Jozef Viglasky, Juraj Klukan, Nadezda Langova
The majority of biomass systems burn woodchips or wood pellets, although agricultural residues and energy crops such as Miscanthus and short rotation coppice based on willow or poplar are also used. While some boilers are designed to take a range of fuels, others are more particular and regular switching between fuels is not practical as combustion settings have to be adjusted to cope with the different burning characteristics. Low-grade woodchips can have a moisture content of 50% or more and will have a relatively low energy density (630–860 kWh/m3 depending on species), while high-grade chips will be expected to be around 30% moisture content (690–930 kWh/m3). High quality wood pellets will be expected to be less than 10% moisture content and will have an energy density of around 3100 kWh/m3.
Agriculture Waste Composites
Published in Magdi El Messiry, Natural Fiber Textile Composite Engineering, 2017
Wood pellets are usually made from sawdust, wood shavings, wood chips or wood logs, any forestry wastes or agro residuals straws, stalks, etc. Figure 7.8 shows the sequence of the wood pellet as: Milling: the process starts with size reduction through milling of the different blend components; Cleaning and Pre-Treatment: to remove the dust and any impurity and pre-treat the material by one of the discussed above techniques;Drying: to achieve a material’s consistent moisture level. Large dryer drums may use natural gas, propane, sawdust burners, or other fuels to heat the drum;Pelletizing: after drying, the sawdust is pressed through dies at high pressure. This process causes the sawdust to heat up and release natural lignin in the wood that binds the sawdust together or to use extruders to give a small size pellets;Cooling: cooling tower is used to bring the temperature down and harden the pellets.
Wood Log and Wood Pellet Heating
Published in Frank Jackson, Dilwyn Jenkins, Renewable Energy Systems, 2013
Wood pellets are a robust new fuel which is a highly versatile wood-based product designed specifically to compete with fossil fuels on convenience and performance. These days, pellets also compete well on price. Furthermore, within the wood-fuel arena, pellets tend to function better than chips in smaller sized heating-systems, paving the way for micro-level biomass. In general pellets offer a number of distinct advantages: drier than comparable fuels such as wood chips;free flowing, almost fluid in nature (homogeneous in size and shape, usually around 6 to 10 mm wide and between 2 and 4 cm long);lower in ash content and unproblematic in ash behaviour;much denser than comparable fuels;easier to store per kWh of heat output;cheaper to transport per kW of heat output;easy to ignite (pellets are dryer and most pellet units boast push button electric starting mechanisms);produce lower emissions than other wood fuel applications;size and shape allow for optimum airflow, which is important for maximising heat outputs;small size facilitates loading via automated boiler feed mechanisms;small size allows for small-scale, highly efficient combustion; andcheaper than oil (and around the same price as natural gas).
Characterization of Portuguese woody biomass: alignment with the ENPlus® standard for the certification of wood pellets
Published in Biofuels, 2023
Leonel J. R. Nunes, Margarida Casau, João C. O. Matias, Marta Ferreira Dias
Wood pellets are made from wood waste such as sawdust, shavings, and chips that are compressed into small, high-density energy cylinders and used as fuel in various heating systems [35]. However, the quality of wood pellets can vary significantly, depending on the type of wood used, the production process, and its origin [36]. ENPlus certification is granted by an independent organization that evaluates the quality of wood pellets in relation to various technical, environmental, and safety requirements, including chemical composition, density, ash content, moisture content, chlorine content, and sulfur content [37]. The certification guarantees that the wood pellets meet rigorous technical requirements and are produced with quality raw materials and appropriate production processes [38].
Impacts of wood species and moisture content on emissions from residential wood heaters
Published in Journal of the Air & Waste Management Association, 2022
Barbara Morin, George Allen, Arthur Marin, Lisa Rector, Mahdi Ahmadi
Updates to the NSPS promulgated in 2015 specify that the PM emissions limits in the regulation apply to pellet stoves, as well as cordwood stoves. Wood pellets are manufactured under heat and pressure from ground sawdust and woodchip byproducts. The FRM for testing pellet stoves, ASTM E2779-10, does not limit the wood species that compose the pellets used for testing. However, the NSPS requires that certification tests use pellets that have been graded under a licensing agreement with an EPA-approved third-party organization and that meet EPA’s specifications for density, dimension, fines, chlorides, and ash, and that do not contain demolition or construction waste or other prohibited materials. Laboratories or manufacturers are allowed to specify or supply the fuel used in the testing [40 CFR § 60.534(e)].
Investigating the future supply distribution of industrial grade wood pellets in the global bioenergy market
Published in Biofuels, 2020
Mohammad S. Roni, Patrick Lamers, Ric Hoefnagels
Wood pellets are the most common form of internationally traded solid biomass for energy use. Uniform in size, shape, moisture, density, and energy content, they fulfill many criteria required for allowing large-scale, bulk trade. Wood pellets do vary according to the manufacturing process and the material from which they are produced. Traditionally, wood pellets are graded according to ash content, energy content, bulk density, and moisture content. Wood pellets have various uses, but are primarily used as a residential heating fuel. Wood pellets can also be used for commercial heating and power generation applications. Other uses include animal bedding and as an absorbent (e.g. in the oil and gas industry). To date, the residential pellet business mainly relies on regional trade; however, industrial-grade wood pellets are traded globally. Over the last decade, global wood pellet production increased substantially from 5.2 tera (1012) gram (Tg) annually in 2005 to 29.7 Tg by 2015 [1]. The European Union (EU) is a major consumer in the wood pellet market. In 2015, the EU produced 14.1 Tg wood pellets, but consumed 20.3 Tg, which is 80% of the global wood pellet production. By 2015, global wood pellet trade was 14.7 Tg, which is approximately 49% of global production, including intra-EU trade [1]. About half the global wood pellet trade takes place within the EU. However, extra-EU trade is increasing rapidly, with the USA and Canada, followed by Russia, being the two largest suppliers.