Evaluation of non-steady state condition contribution to the total emissions of residential wood pellet stove Elisa Venturini a, 1 , Ivano Vassura a, b, * , Cristian Zanetti b , Andrea Pizzi c , Giuseppe Toscano c , Fabrizio Passarini a, b a University of Bologna, Interdepartmental Center for Industrial Research “Energy and Environment”, Via Angher a 22, I-47900 Rimini, Italy b University of Bologna, Department of Industrial Chemistry “Toso Montanari”, Viale Risorgimento 4, I-40146 Bologna, Italy c Polytechnic University of Marche, Department of Agricultural, Food and Enviromental Science (D3A), Via Brecce Bianche 10, I-60131 Ancona, Italy article info Article history: Received 31 March 2015 Received in revised form 15 May 2015 Accepted 25 May 2015 Available online xxx Keywords: Heating system Biomass combustion Heavy metal Particulate matter (PM) PAH Soluble ions abstract In order to evaluate non-steady phase contribution to the total emissions of a pellet stove in real do- mestic operations, particulate matter and gaseous emissions were determined separately for different operating conditions, i.e. ignition, partial load, increase in power and nominal load. TSP (Total suspended particulate) was sampled with a dilution system and characterized for TC (total carbon), PAHs (polycyclic aromatic hydrocarbons), the main soluble ions, Ni, As, Cd and Pb. Gas monitoring shows that CO and NO emission factors in ignition phase markedly differ from other operating conditions: NO emission factor is lower, while CO one is much higher, since it is a product of incomplete combustion. Start-up phase emission factors are also higher for TSP, Cd and other products of incomplete combustion, i.e. TC and PAHs. Despite being a non-steady phase, the increase in power phase emission factors appreciably differ from steady state ones only for PAHs. Moreover, the PAHs emitted in non-steady state phases have a higher toxicological burden. In conclusion, in order to evaluate the real impact of pellet stove on the environment, transient conditions should be taken into account. The ignition phase, even though it lasts only 20 min, can significantly contribute to pollutant emission. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction Wood pellet has become an important worldwide fuel. Pellet devices as heating system were introduced about 20 years ago. In last years, their use in Europe-28 has strongly increased. Further- more, reliable estimates indicate that their use will also increase in next years. According to the estimates, Italy will be one of the greater users of these systems in 2020, together with Germany and Belgium [16]. In Italy, the demand for wood pellet has increased steadily since 1999, led by the growth of the pellet stoves sector. In 2012, the consumption of pellet reached over 2,000,000 tons, thus confirm- ing Italy as Europe's biggest market for pellet domestic use. In Italy, the large majority of pellets are used for space heating in the res- idential sector; it is estimated that about 90% is consumed in stoves and the remaining 10% is used in boilers [1,18]. The use of woody biomass as fuel in combustion plants to pro- duce heat or electricity is also promoted in Europe by Directive 2009/28/EC [13], which aims to reduce nonrenewable resource consumption. Furthermore, the use of biomass is regarded “CO 2 neutral”, and this is a fundamental characteristic in order to reduce of 20% greenhouse gas emission within 2020, as established by 2009/29/CE Directive [14]. Nevertheless, despite the general opinion, the use of wood pellets in stove sector is not carbon neutral. As a matter of facts, the production and mainly the trans- port of wood pellets (frequently imported from other countries) Abbreviations: IG, Ignition; PL, Partial load; IP, Increase in power; NL, Nominal load; DT, Dilution tunnel; DRs, Dilution ratios; Flu, Fluoranthene; Pyr, Pyrene; B(a)A, Benz[a]anthracene; Cri, Chrysene; B(b)F, Benzo[b]fluoranthene; B(k)F, Benzo[k] fluoranthene; B(a)P, Benzo[a]pyrene; D(a,h)A, Dibenz[a,h]anthracene; B(g,h,i)P, Benzo[ghi]perylene; I(1,2,3)P, Indeno[1,2,3-cd]pyrene; QV, Dry volumetric gas flow; Qm fuel , Mass flow feeding fuel; NHV, Net heating value. * Corresponding author. University of Bologna, Department of Industrial Chem- istry “Toso Montanari”, Viale Risorgimento 4, I-40146 Bologna, Italy. Tel./fax: þ39 051 2093863. E-mail addresses: elisa.venturini6@unibo.it (E. Venturini), ivano.vassura@unibo. it (I. Vassura), cristian.zanetti@studio.unibo.it (C. Zanetti), a.pizzi@univpm.it (A. Pizzi), g.toscano@univpm.it (G. Toscano), fabrizio.passarini@unibo.it (F. Passarini). 1 Present address: University of Bologna, Department of Industrial Chemistry “Toso Montanari”, Viale Risorgimento 4, I-40146 Bologna, Italy. Contents lists available at ScienceDirect Energy journal homepage: www.elsevier.com/locate/energy http://dx.doi.org/10.1016/j.energy.2015.05.105 0360-5442/© 2015 Elsevier Ltd. All rights reserved. Energy xxx (2015) 1e8 Please cite this article in press as: Venturini E, et al., Evaluation of non-steady state condition contribution to the total emissions of residential wood pellet stove, Energy (2015), http://dx.doi.org/10.1016/j.energy.2015.05.105