Briquetting of Poplar Wood from Short Rotation Coppice—The Effects of Moisture Content and Hammer Mill Screen Size

Studies on the use of biomass from short rotation coppices for briquette production as a sustainable biofuel have been scarce in the literature. This study investigated the effects of two process variables, hammer mill screen size at three levels (5.3, 10.3, and 25.4 mm) and moisture content at three levels (13.6, 19, and 25% (w.b.)), on the properties of briquettes from poplar Max-4 trees. The whole tree was divided into two fractions, the crown and the stem, and briquettes were produced from them. The effects of the variables on compressed density, relaxed density, relaxation ratio, and the shatter index of the briquettes were analyzed. The results showed that the combined interaction of the variables had no significant effects (p > 0.05) on the compressed density, relaxed density, and relaxation ratio of the briquettes. However, hammer mill screen size and moisture content both significantly influenced the shatter index irrespective of the tree fraction (p < 0.05). Hammer mill screen sizes of 5.3 and 10.3 mm at moisture contents of 13.6 and 19% (w.b.) resulted in good quality briquettes across the properties investigated for both the crown and stem poplar tree fractions. This study shows that high-quality briquettes can be produced from poplar Max-4 woody biomass

Options for optimizing the drying process and reducing dry matter losses in whole-tree storage of poplar from short-rotation coppices in Germany

For sustainable production of wood in short-rotation coppices and agroforestry systems, it is necessary to optimize the storage processes to achieve low dry matter losses together with low-cost drying. The harvesting of the trees can be carried out very efficiently with modified forage harvesters or tractor-powered mower-chippers. The wood chips produced can be dried naturally at low cost in open-air piles. However, this type of storage is connected with high dry matter losses of up to about one fourth in the course of seven-month storage. Although harvesting whole trees is connected with significantly higher costs, lower dry matter losses are to be expected from storing the trees in piles. Consequently, in this study, the storage and drying behavior of poplar under different German weather conditions and depending on the structure of the storage piles has been examined in detail. After a seven-months storage period, the trees still displayed moisture contents of 41–44% following an initial moisture content of 56% but achieved very low dry matter losses of only 4–7%. Moisture contents of 35–39% could only be achieved in October after a further two-months drying period under favorable weather conditions. All storage piles were built up on approximately 30 cm high support timbers for better ventilation. Additionally, covering the ground with a fleece did not have any influence on the drying behavior, nor did different pile heights. Smaller tree trunk diameters are not only connected with a higher share of bark or ash, but also thinner trunks tend to become damp again more quickly after rainfall. That is why whole-tree storage is suitable above all for medium or longer rotation periods with which, under favorable conditions, the higher harvesting costs can be compensated by a higher wood chip quality and lower storage losses

An Assessment of Potential Resources for Biomass Energy in Nigeria

Nigeria is a developing country with an insufficient supply of energy to meet the continuously growing demand. However, there are several biomass resources available within the country. This paper presents a desk review, which investigates the potential resources for biomass energy generation within the country. Energy policies to aid biomass use as an energy source within the country were also reviewed. Biomass resources identified within Nigeria include forest residues, agricultural residues, human and animal wastes, aquatic biomass, and energy crops. However, several of the resources, particularly agricultural residues, have competing uses, such as livestock feed and soil rejuvenation. An estimation of the technical energy potential of the biomass resources revealed that about 2.33 EJ could be generated from the available resources in Nigeria. Agricultural residues have an energy potential of about 1.09 EJ, with cassava, maize, oil palm, plantain, rice, and sorghum being the major contributors. Animal wastes, municipal solid waste, and forest residues have energy potentials of 0.65, 0.11, and 0.05 EJ, respectively. The potentials of wood fuel and charcoal are 0.38 and 0.05 EJ, respectively. The study found that despite the available potential and existing policies, not much has been done in the implementation of large-scale bioenergy within the country. However, there has been laboratory and research-scale investigations. The review suggests that more policies and stronger enforcement will aid bioenergy development within the country. From the review, it has been suggested that the agricultural sector needs to be developed to generate more biomass resources. More research, development, and implementation have to be carried out on biomass resources and bioenergy generation processes. The production of non-edible energy crops in marginal lands should also be considered prime to the development of bioenergy within the country

Technical paper on Twin screw extruder processing technology for fibres as raw material for peat substitution

One important aim of the Organic-PLUS project is to develop resource and energy efficient technologies to produce fibres from lignocellulosic plant materials as a raw material to substitute peat. For this purpose, Leibniz Institute für Agrartechnik und Bioekonomie (ATB), Germany leads the work in the task 5.3, “Processing of agroforestry and other plant material for improved characteristics”. This report (Project deliverable D5.3) describes one technology available at pilot scale at ATB which changes the characteristics of plant fibres to make them better suited for peat replacement. The process is called extrusion, and is described in this report. The purpose is to inform stakeholders interested in peat replacement, including scientists involved in the Organic-PLUS project, to collect relevant materials for extrusion and to test further utilisations of extruded fibres

Influence of Processing Parameters on Fibre Properties during Twin-Screw Extrusion of Poplar Wood Chips

For sustainable agriculture, the contentious input of peat in growing media needs to be replaced by a substitute with the best possible water-holding capacity (WHC). Wood from fast growing poplar trees, cultivated in short rotation coppices (SRC), is a suitable alternative if it is processed correctly in a twin-screw extruder. The processing parameters, such as the aperture setting of the extruder, moisture content, and specific energy demand (SED), during twin-screw extrusion, as well as their influence on fibre properties such as WHC and particle size distribution, are investigated. SRC-poplar wood chips from clone Max3 are the raw material used for this research. As a result, the best volume-based WHC (75%) at −1 kPa suction tension was achieved for dry extruded wood chip fibre at an aperture setting of 15 mm and an SED of 340 kWh*t−1. The smallest SED of 140 kWh*t−1 was measured at apertures of 35 mm and 40 mm, which resulted in a volume-based WHC of approximately 30% and a dry matter mass flow during processing of 0.289 t*h−1 (40 mm). The particle size distribution of semi-dry wood chips has the highest fine fraction as well as the smallest coarse fraction. Conclusively, poplar wood can be processed fresh and dry into fibre at an acceptable SED, which results in an acceptable WHC

Storage Problems of Poplar Chips from Short Rotation Plantations with Special Emphasis on Fungal Development = Rövid vágásfordulójú nyár apríték tárolási problémái, különös tekintettel a kifejlődő gombákra

There are several problems in storing wood chips freshly harvested from short rotation plantations, which result in quality losses as well as in dry matter and energy losses. The factors influencing the degradation of raw material are examined in this paper with special focus on fungal development. An excessive growth of fungi is connected to dry matter losses and also to an increased health risk during raw material handling. The following factors were measured during 6 months storage of poplar wood chips depending on particle size: box temperature, moisture content, pH-value, appearance of fungi in the storage and the concentration of fungal particles in the air. The results show a close connection between particle size, temperature and attack of fungi. During the storage mesophilic and termophilic species of the genera Alternaria, Aspergillus, Cladosporium, Mucor and Penicillium appeared. The concentration of fungal particles is the highest for fine chips and decreases in bigger particles. There was a special focus on the investigation of the properties of coarse chips (G 50), which represent a good compromise between handling, storage losses and health risk due to fungal development. | Frissen kitermelt rövid vágásfordulójú fafajokból előállított apríték tárolása során számos probléma merül fel, melyek eredménye minőség-, szárazanyag- és energiaveszteség. Ebben a tanulmányban a nyersanyag-degradációt befolyásoló tényezők kerültek vizsgálatra, különös tekintettel a kifejlődő gombákra. Ezek rendkívüli elszaporodásának köszönhető a szárazanyag-veszteség mellett a nyersanyag kezelése során fellépő, megnövekedett egészségügyi kockázat is. Nyár faapríték hat hónapos tárolása folyamán az aprítékméret függvényében a következő tényezők mérése zajlott: a tárolón belüli hőmérséklet, nedvességtartalom, pH, a tárolóban megjelenő gombák és azok száma a levegőben. Az eredmények szoros összefüggést mutatnak, különösen az aprítékméret, a hőmérséklet és a gombák száma közt. A tárolás során mezofil és termofil gombák fejlődtek. A következő nemzetségekhez tartozó fajok voltak megfigyelhetők: Alternaria, Aspergillus, Cladosporium, Mucor, Penicillium. A gombák száma a finom aprítéknál volt a legmagasabb, ami az aprítékméret növekedésével csökkent. A kutatás folyamán különös szerepet kapott a középfinom apríték tulajdonságainak vizsgálata (G 50), mely kompromisszumos megoldást jelent a kezelés, tárolási veszteségek és a kifejlődő gombáknak köszönhető egészségügyi kockázatok között

Storage problems of poplar chips from short rotation plantations with special emphasis on fungal development

There are several problems in storing wood chips freshly harvested from short rotation plantations, which result in quality losses as well as in dry matter and energy losses. The factors influencing the degradation of raw material are examined in this paper with special focus on fungal development. An excessive growth of fungi is connected to dry matter losses and also to an increased health risk during raw material handling. The following factors were measured during 6 months storage of poplar wood chips depending on particle size: box temperature, moisture content, pH-value, appearance of fungi in the storage and the concentration of fungal particles in the air. The results show a close connection between particle size, temperature and attack of fungi. During the storage mesophilic and termophilic species of the genera Alternaria, Aspergillus, Cladosporium, Mucor and Penicillium appeared. The concentration of fungal particles is the highest for fine chips and decreases in bigger particles. There was a special focus on the investigation of the properties of coarse chips (G 50), which represent a good compromise between handling, storage losses and health risk due to fungal development.Rövid vágásfordulójú nyár apríték tárolási problémái, különös tekintettel a kifejlődő gombákra. Frissen kitermelt rövid vágásfordulójú fafajokból előállított apríték tárolása során számos probléma merül fel, melyek eredménye minőség-, szárazanyag- és energiaveszteség. Ebben a tanulmányban a nyersanyag-degradációt befolyásoló tényezők kerültek vizsgálatra, különös tekintettel a kifejlődő gombákra. Ezek rendkívüli elszaporodásának köszönhető a szárazanyag-veszteség mellett a nyersanyag kezelése során fellépő, megnövekedett egészségügyi kockázat is. Nyár faapríték hat hónapos tárolása folyamán az aprítékméret függvényében a következő tényezők mérése zajlott: a tárolón belüli hőmérséklet, nedvességtartalom, pH, a tárolóban megjelenő gombák és azok száma a levegőben. Az eredmények szoros összefüggést mutatnak, különösen az aprítékméret, a hőmérséklet és a gombák száma közt. A tárolás során mezofil és termofil gombák fejlődtek. A következő nemzetségekhez tartozó fajok voltak megfigyelhetők: Alternaria, Aspergillus, Cladosporium, Mucor, Penicillium. A gombák száma a finom aprítéknál volt a legmagasabb, ami az aprítékméret növekedésével csökkent. A kutatás folyamán különös szerepet kapott a középfinom apríték tulajdonságainak vizsgálata (G 50), mely kompromisszumos megoldást jelent a kezelés, tárolási veszteségek és a kifejlődő gombáknak köszönhető egészségügyi kockázatok között

Solid Biofuel Production from Biomass:Technologies, Challenges, and Opportunities for Its Commercial Production in Nigeria

Producing durable and efficient solid biofuels should be an important consideration in Nigeria’s present economy due to the numerous advantages associated with it. It offers the benefit of energy generation, particularly in rural areas, and could potentially replace fossil fuels. However, the adoption and production of solid biofuels at commercial scale in Nigeria is limited by some challenges, including the lack of a developed supply chain structure, inadequate facilities, and air pollution. The present study summarizes the types of solid biofuel production technologies deployed in Nigeria as well as the biomass feedstock utilized in the production of fuel briquettes and pellets. While opportunities exist in the gasification of biomass in Nigeria, direct combustion is a readily applicable fuel conversion process that can be utilized to generate electricity from solid biofuel. The major challenges surrounding the full adoption of solid biofuel production and utilization in Nigeria are highlighted. Among others, promotion of clean energy alternatives, investments and financial incentives, sustainable renewable energy policy and energy transition plan, and legislative backing are identified as factors that could accelerate the commercial production and adoption of solid biofuel in Nigeria

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