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The applicability of spruce, sunflower and maize for residential heating was investigated. Emission factors of gaseous and PM pollutants were established at both nominal and reduced output. Since automatic pellet boilers often operate at reduced output, understanding the differences in PM release and behavior is crucial. The emission factors for sunflower reached the highest values at 111.6 mg MJ−1 and 139.2 mg MJ−1 for nominal and reduced output, respectively. PM emission factors reached 49.5/39.5 mg MJ−1 for maize and 8.6/21.4 mg MJ−1 for spruce. It was shown that PM size distribution does not vary significantly between nominal and reduced output and is highly dependent on the fuel composition. The PM size peak was in the range of 0.377–0.596 μm for sunflower, 0.252–0.377 μm for maize, 0.152–0.252 μm for spruce at nominal output and 0.0941–0.152 μm for spruce at reduced output. The entrainment of coarse ash particles was found to be negligible. Cd, Pb, Tl and Sb were found almost exclusively on emitted particles, due to their high volatility and modes of occurrence. The release of inorganic matter into the flue gas was severely inhibited in maize due to the formation of refractory phases. • Submicron particles make up the majority of combustion-generated PM. • Inorganic matter has a prominent effect on total PM emissions in non-woody biomass. • Clinkers and slag inhibit the release of inorganics and certain trace elements. • Severe fouling due to KCl occurs when firing sunflower husks. [ABSTRACT FROM AUTHOR]

Microalgae-based solid biofuels offer a promising option for efficient and low-cost utilizations of microalgae. This work investigates the key aspects of microalgae-based solid fuels, from production to combustion, based on the perspective of microalgae's complete carbon cycle, from culture to utilization. Additionally, recent advances in research on the physical properties, energy consumption during production, and combustion characteristics of microalgae-based solid fuels were evaluated. The results show that microalgae is viewed as a promising feedstock for the production of solid fuels and constitutes a widely followed topic of research. Nowadays, co-pelletization and co-combustion of microalgae with other biomass is considered the most competitive way to utilize microalgae-based solid fuels. The addition of about 10–30% microalgae can reduce the energy consumption of the original pelletizing process by about 24–28%, while the density, durability and calorific value of the solid fuel can be significantly increased. More importantly, thanks to the high lipid content of microalgae, its addition can effectively improve the combustion performance of coal, sludge and typical biomass fuels, as well as positively influence the combustion process. Finally, the opportunities and challenges for microalgae-based solid biomass feedstock was discussed, including the impact of species diversity on algae-based solid fuels, an exploration of further industrial applications, and possible integration pathways with the existing microalgae industry chain. • Main emphasis is on review of production and combustion of algae-based solid fuels. • Microalgae-based solid fuels can be seen as a new option for achieving carbon neutrality. • The co-pelletization and co-combustion of microalgae with different materials is synergistic. • Microalgae additions of 10–30% seem to be a promising option. • Microalgae are an excellent raw material or additive for the manufacture of solid fuels. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the effect of emission trade on the development of the wood fuel market and on the balance of the demand and supply of wood fuels in Finland was evaluated. The demand for wood fuels was estimated to double by the year 2010 to almost 50TWh, of which 17TWh can be forest chips. In 2010, the supply potential of by-products was estimated to be 28TWh, of which 11TWh was marketable outside the internal use of the forest industry. Correspondingly, the theoretical potential of forest chips was estimated to be 51TWh and the techno-economical potential 24TWh, which made up the potential market supply. As a result of the regional optimization model, the energy use of wood fuels was 33TWh, which was 68% of the potential demand in the emission trade situation. Regionally, the potential demand for wood fuels for energy use was higher than the supply in all provinces. [Copyright &y& Elsevier]

Abstract: The chemical composition of solid biofuels (as defined in [Directive 2000/76/EC of the European Parliament and of the Council on the Incineration of Waste. In: European Commission, editor. Official Journal of the European Communities, vol. L 332; 2000. p. 91–111] and [CEN/TC 335—WG2 N94. Final draft. European Committee for standardization, editor. Solid biofuels—fuel specifications and classes. Brussels, Belgium; 2003.] has manifold effects on their thermal utilisation. C, H and O are the main components of solid biofuels and are of special relevance for the gross calorific value, H in addition also for the net calorific value. The fuel N content is responsible for NO x formation. NO x emissions belong to the main environmental impact factors of solid biofuel combustion. Cl and S are responsible for deposit formation and corrosion and are therefore relevant for a high plant availability. Furthermore, Cl causes HCl as well as PCDD/F and S SO x emissions and both elements are involved in the formation of aerosols (submicron particle emissions). The ash content influences the choice of the appropriate combustion technology and influences deposit formation, fly ash emissions and the logistics concerning ash storage and ash utilisation/disposal. Major ash forming elements (Al, Ca, Fe, K, Mg, Na, P, Si, Ti) are of relevance for the ash melting behaviour, deposit formation and corrosion. In addition, volatile elements such as Na and K are main constituents of aerosols. Volatile minor elements (As, Cd, Hg, Pb, Zn) play a major role in gaseous and especially aerosol emissions as well as in deposit formation, corrosion and ash utilisation/disposal. Either partly or non-volatile minor elements (Ba, Co, Cr, Cu, Mo, Mn, V) are of special relevance for ash utilisation. The present paper discusses the influence of chemical fuel properties on biomass combustion plants as well as possibilities and recommendations for controlling them. [Copyright &y& Elsevier]

Abstract: The development of reliable and appropriate methods for the accurate determination of major (Al, Ca, Fe, K, Mg, Na, P, Si, Ti) and minor (As, Ba, Cd, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, Sb, Tl, V, Zn) ash-forming elements in solid biofuels was the major goal of Task III.2 of the EU project BioNorm. For this purpose, wood+bark, straw and olive residues were analysed using several digestion and determination methods. The digestion methods included wet decomposition in closed vessels with different acid mixtures as well as dry-ashing techniques. The determination systems included FAAS, GFAAS, CVAAS, ICP-OES, ICP-MS, XRF as well as direct Hg-determination. Tests were carried out to optimise the methods applied. To summarise the outcomes of these tests, different digestion procedures were developed for major and minor elements. Digestion with H2O2/HNO3/HF followed by neutralisation with H3BO3 was validated for major element analyses, while digestion with H2O2/HNO3/HF was validated for minor element analyses. The validation results show that the applied digestion methods can be recommended for solid biofuel analyses. For the determination of the elements investigated in solid biofuels, the following detection systems can be recommended: FAAS for Ca, Fe, K, Mg, Na, Si, Mn, Zn; ICP-OES for Al, Ca, Fe, K, Mg, Na, P, Si, Ti, Mn, Zn, Ba, Cr, Cu, Mn, Ni, V, Zn; GFAAS for Cd, Cr, Cu, Ni, Pb; ICP-MS: P, Ti, As, Ba, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Sb, V, Zn and direct determination as well as CVAAS for Hg. [Copyright &y& Elsevier]

Abstract: The European Committee for Standardization, CEN (TC335) is currently preparing 30 technical specifications for solid biofuels. The two most important technical specifications being developed deal with classification and specification (CEN/TS 14961) and quality assurance for solid biofuels (CEN/TS 15234). The classification of solid biofuels is based on their origin and source. The fuel production chain of fuels shall be unambiguously traceable back over the whole chain. The biofuels are divided into the following sub-categories for classification: (1) woody biomass, (2) herbaceous biomass, (3) fruit biomass and (4) blends and mixtures. The purpose of classification is to allow the possibility to differentiate and specify biofuel material based on origin with as much detail as needed. The quality classification in a table form was prepared only for major traded solid biofuels: briquettes, pellets, exhausted olive cake, wood chips, hog fuel, wood logs, sawdust, bark, and straw bales. Additionally, a general table was compiled for other biofuels. The most significant properties are normative, and shall be stated in the fuel specification. The classification is flexible, and hence the producer or the consumer may select from each property class the classification that corresponds to the produced or desired fuel quality. This so-called “free classification” does not bind different characteristics with each other. An advantage of this classification is that the producer and the consumer may agree upon characteristics case-by-case. To protect household consumers, examples of so-called “high-quality” fuels are given as an informative annex A of CEN/TS 14961. This paper describes the fuel specifications and classes of solid biofuels, which was published in April 2005. [Copyright &y& Elsevier]

Abstract: A Quality Assurance (QA) system taking the overall supply chain of solid biofuels into account is essential for an increased trade and use of these energy carriers. A methodological approach is necessary which ensures—besides an efficient control of the single processes considered throughout the overall chain—also the control over the overall supply chain by an adequate integration of previous and subsequent process steps controlled different organisational units. Such a QA-system needs to provide tools to demonstrate that the level of quality demanded by customers is achieved and that their confidence in biofuels is enhanced. Against this background this paper shows the characteristics of solid biofuels with respect to the necessary supply chain and the need for a Quality Management (QM) system with emphasis on QA and Quality Control (QC). Furthermore, a step-by-step methodology is presented which helps operators running the overall or parts of the supply chain to implement and to apply an appropriate QM-system. Additionally important terms and customer requirements are explained. The system described is compliant with the requirements of the Technical Specification CEN/TS 15234 Fuel quality assurance elaborated by CEN/TC 335. [Copyright &y& Elsevier]

Our holistic study, firstly, developed pellets with extract of illicit cigarette's tobacco for controlling off-gassing of CO 2 then quantitatively analyzed the implications of this addition to combustion, tendency for slagging and fouling, and toxicology of the final product. The production of pellets consisted of adding 0.10 L of extract at 0.05% v v−1 to 2.00 kg of feedstock by stirring or spraying then pressing on an automatic pelletizer machine at 200.00 MPa and 125.00 °C. The monitoring and quantification of auto-generation of gas from pellets under steady-state atmosphere lasted for one month. Usage of extract by spraying effectively reduced the absolute-growth rate of autoxidation of extractives and activity of off-gassing in 3.70% g−1 pellets d−1 and 217.40 mg CO 2 kg−1 pellets d−1, respectively, but slightly accelerated the combustion, tended more to slagging and fouling, and increased the emissions of NO x , SO 2 , and volatile organic compounds. However, solid biofuels met the rigors for manual and automatic wood-burning appliances and contained tobacco-specific harmful and potentially harmful compounds nearly an order of magnitude below toxicant levels of occupant discomfort and sensory irritation. Our findings are timely and provide valuable knowledge on the ability of the extract to function as an alternative radical terminator and thus considerably decelerate the time-dependent activity of off-gassing. This antioxidant will open up the horizons for utilization of pellets as solid biofuels in cleaner and safer bioenergy producing systems and assist with tackling environmental and social consequences of spontaneous generation of gases and explosions in home-made and industrial settings. [Display omitted] • A powerful antiradical for stabilizing self-oxidizable solid biofuel. • Deceleration of kinetics and reduction of off-gassing of CO 2 in 217.40 mg kg−1 • Experiments on combustion, slagging, and harmful and potentially harmful compounds. • Acceptable emissions of noxious volatiles for occupational safety recommendation. • Pelletization as an eco-friendly tobacco-to-biofuel pathway. [ABSTRACT FROM AUTHOR]

In order for solid biofuels to be marketable and accessible to stakeholders (e.g., manufacturers, transhippers and customers), they must strictly meet the rigors of international standards and regulatory agencies regarding quality. On this basis, this study assesses the production of high-performance fuel-flexible woody pellets for heating and power, with the assistance of multivariate statistical process control (MSPC). The operational scenarios of industrially pelletizing pinewood sawdust are POS I (150 MPa and no pre-heating) and POS II (250 MPa and no pre-heating) as references, and POS III (150 MPa and pre-heating) and POS IV (250 MPa and pre-heating) as alternatives to regularize the workflow on the machine. The stream-monitoring techniques of MSPC are the exponential moving average (EMA) and Hotelling's T 2 . The EMA-Hotelling system accurately tracks non-random errors and predicts the operationally finest scenario for developing high-quality pellets. Pre-heating the compressing channel of the machine regularizes the feeding and thus produces type I pellets (class A 1 /A 2 , European standard) with excellent bulk density (1227.55 kg m−3), durability (98.10%) and hydrophobicity (96.65%), without points outside the specific critical ranges. Clear evidence of improved pellet quality with the assistance of MSPC is found. The high-fidelity concept of MSPC captures the advantages of EMA and Hotelling's T 2 into an immersive single framework; hence, it can compensate for the potential bias and misinformation-to-information overlapping of outcomes from monitoring latently multivariable flow on classical quality control charts. The major findings and innovations of this study can assist with rolling-out fine-scale pelletization and thus fulfill the increasing global demand for high-quality biofuels. [Display omitted] • An auspicious EMA-Hotelling system to roll-out fine-scale pelletization. • High-fidelity concept of upstream-monitoring charts. • Solid biofuels with 1227.55 kg m−3 bulk density and 98.10% durability. • Pre-heating to regularize workflow and level up thermomechanical densification. • Set of accurate collinearities for multi-objective optimization on the machine. [ABSTRACT FROM AUTHOR]

As part of a comprehensive evaluation of the use of Sida hermaphrodita (hereafter referred to as Sida) biomass as a solid biofuel, a life cycle assessment (LCA) according to ISO 14040/14044 was carried out by means of a suitable cradle-to-gate system design. The supply and use of chips, pellets and briquettes was studied by internal and external comparisons to show competitiveness and improvement options. The results show fewer differences within the Sida process chain designs but larger distinctions to compared alternative biofuels such as wood or Miscanthus pellets. A major finding is that Sida process chains cause lower environmental impacts in comparison with alternative biofuels. The study identified hot spots within the Sida process chains and starting points for further improvement. A sensitivity analysis of important parameters, such as specific yield or heating values was performed. Because there are no similar investigations on the environmental impact of Sida used as a biogenic solid fuel to date this manuscript presents first results. So far, the results indicate that Sida provides a more sustainable option for the use of biomass in combustion processes in relation to environmental impacts. Image 1 • Env. impacts of Sida biofuels were compared to those of woody & Miscanthus biofuels. • 70–80% of compared process chains cause larger environmental impacts than Sida. • More advantageous environmental impacts are also given with lower yields of Sida. • Not all impact causes are accessible for impact lowering due to non-influenceability. [ABSTRACT FROM AUTHOR]

Torrefied biomass is said to have potential as a replacement for coal. One of the main goals of torrefaction is to make biomass resemble coal more in terms of its properties as a solid fuel. As a fuel, a novel fuel that is produced by thermal treatment of raw biomass, biocoal has to comply with the regulations of solid fuels from different regulatory bodies. The production regime is different in comparison to the thermally treated fuel already established on the market, such as charcoal. This might raise an issue with the bodies controlling the circulation of chemical substances in the market, such as ECHA in Europe. The aim of this paper is to recommend suitable analytical techniques in order to enable effective quality control. This is necessary if biomass of low and highly variable quality is supposed to become more uniform and turn into a commodity. Information given in many published studies seems sufficient to use of FTIR and NIR as quality control techniques. The use of NMR can be complementary but is limited due to the high cost of the analytical equipment and time-consuming sample preparation. Rapid testing techniques, such as FTIR ATR or NIR, might prove feasible for quality control of solid biofuels, such as biocoal, especially for in-house quality control purposes. This way proper quality assurance and compliance with various novel regulations, such as REACH, could be assured. Further research could be helpful, especially if results would be available in publicly available databases, such as Phyllis. • The need of wider use of novel, rapid analytical techniques is outlined. • Novel analytical techniques, suitable for biocoal are described and compared. • The literature on the analysis of biocoal, using techniques such as FTIR, NIR and NMR, is a subject of detailed review. • Peaks, already determined in the literature, within the spectra of the aforementioned techniques, are listed in tables. • Areas of future development and advantages of the novel techniques are assessed. [ABSTRACT FROM AUTHOR]