production, storing and - cercetare, protectie mediu, …from this type of biomass, such as firewood, briquettes, pellets, wood chips, the storing in marketing logistic centres and

ECOTERRA - www.ecoterra-online.ro Journal of Environmental Research and Protection 2014, Volume 11, Issue 1 43

ECOTERRA Journal of Environmental Research and Protection Wood biomass – production, storing and assessment from the quality viewpoint 1Mihaela Begea, 1Corina M. Berkesy, 1Mircea Crăciun, 1Liviu Suciu, 2Laszlo E. Berkesy, 1Mihaela Andreica

1 S.C. ICPE Bistrita S.A., Bistrita, Romania; 2 Faculty of Environmental Science and Engineering, University Babeş-Bolyai Cluj-Napoca. Corresponding author: C. M.Berkesy,

[email protected]

Abstract. The biomass represented by such organic matters as wood and agricultural organic residues is one of the oldest and most widespread sources of energy. Even nowadays, biomass and especially the wood-derived biomass, under the form of sawdust, wood shavings, wood remainders, bark or other biogenic fuels constitutes, one of the most popular fuels, notably at present, when the price of fossil fuels is rising. This paper sets out certain aspects regarding the technologies of extracting the wood biomass from forests, certain ways of obtaining products from this type of biomass, such as firewood, briquettes, pellets, wood chips, the storing in marketing logistic centres and the assessment from the quality viewpoint. Key Words: wood biomass, pellets, briquettes, wood chips, logistic centre, quality parameters.

Introduction. The valorisation of the renewable energy resources could contribute to the implementation of strategies with a view of enhancing energy security by diversifying the energetic resources and reducing imports. The forest represents a major component for the so-called natural capital that must always be used for designing sustainable development and management. By accepting this principle we will have the guarantee that this natural capital will have a continuous utilisation to the benefit of both the current and future generations (http://www.scribd.com/doc/ 48088810 /Silvi-Cultura).

Thanks to the very high biodiversity, to the impressive sizes of the trees and to their pretty extended longevity, the forest has an unexpected capacity of adaptation to the environment conditions and therefore a very high ecological stability and a perenniality hard to reach by other ecosystems. Consequently, the forest can be seen as one of the most evolved terrestrial ecosystems that receive, process, transform substances and energy from the environment and assign the same to it.

The rhythm of biomass acccumulation differs a lot, depending first of all on the environmental conditions and on the nature of the forest species. At the planet level the biomass accumulation – the primary production expressed in g/m2/year is ascertained to be 1290 g/m2/year. The analysis for the distribution of Romania’s forest vegetation and forest fund landmass at the level of 2011 shows that it represents 27% of the country’s landmass, distributed relatively evenly on the three landforms: mountains (30%), hills (37%) and plains ( ≈ 33%). Out of the entire annual possibility of exploitation of 22.3 Mio. m3, the annual exploitation rates provide 16÷17 Mio. m3 exploited on a yearly basis, so less than the annual exploitation possibilities (Table 1).


Table 1 Forest fund and annual exploitation rate course between 1990 and 2010

Year Forest fund landmass

[K ha] Forest landmass

[K ha] Annual exploitation rate

[K m3] 1990 6,371 6,252 16,649 1995 6,369 6,245 13,813 2000 6,366 6,223 14,285 2005 6,391 6,233 15,671 2009 6,495 6,334 16,520

Wood biomass. The most common utilisation of the wooden biomass for producing thermal energy is represented by firewood (the round bark-covered wood). In the past 10 years, the amount of utilisation of the wooden biomass under the form of briquettes and pellets has increased as well, mainly owing to the environment protection laws, which compel trading companies to valorise the wooden waste materials from wood processing.

Recent researches (Budău et al 2011) have shown that the wooden biomass reserves that can be turned into briquettes or pellets and used as sources of thermal energy are significant. And we only talk about the amounts of processing remainders and sawdust resulted from timber cutting.

The biomass represented by such organic matters as wood and agricultural organic residues is one of the oldest and most spread sources of energy. Even nowadays, biomass and notably wood biomass constitute one of the most popular fuels in the world, especially now, when the price of fossil fuels is on rise. Be under the form of sawdust, shavings, wood remainders, bark or other biogenic fuels, the biomass it is easy to get. Even the fuels with high moisture, stored in the open air, do not represent a problem for the modern heating plants. Biomass is available in almost any region of the country, without needing high transport costs (http://www.bracon.ro/Produse şi servicii/Energie din lemn/BIOMASA-avantajele căldurii_din_lemn).

The wooden waste materials derived from the process of obtaining timber, furniture, pallets and paper represent around 50% of the harvested wood material, thus constituting a vast raw material for manufacturing the wood material used for heating purposes (pellets, briquettes, wood chips). The manufacturers of the wood heating systems, notably those that make small- to big-sized devices, need these fuels available on the market to comply with the quality standards according to which the heating plants are tested and certified (Figure 1).

Figure 1. Chopped wood, wood chips, pellets, briquettes, firewood. The regulations included in the EU laws for the ecological field, namely the full valorisation of the wood waste materials resulted from primary and secondary processing operations, are observed by the placement of stationary compacting equipment in the specific technological flow, at each undertaking in the field. As for the energetic plant crops, Romania meets the conditions for their cultivation from the geographical standpoint: a balanced territory, very good pedoclimate


conditions, the cultivation of a wide range of energetic plants and the potential surface - approx. 12% tillable (without prejudicing food security). Biomass utilisation has advantages for the environment protection and not only thanks to the low pollution. By obtaining energy from biomass, any waste of food excesses is prevented, the waste materials given rise to by the forest industry and by farms are managed and the urban waste materials are recycled (Figure 2).

Figure 2. Romania’s energetic biomass potential.

Chopped wood (wood chips). The chopped wood (the wood chips) is represented by small pieces of wood whose moisture is usually reduced. The chopped wood (the wood chips) is obtained by means of the splintering machines, which are specially designed to break wood into small fragments (Figure 3). Figure 3. Machine for obtaining chopped wood or wood chips under the form of chips, which can be either stationary or mounted on a frame, a trailer, a truck or on the three-point coupling behind a

tractor. Such a machine can be fitted with its own engine or it can be activated by the power take-off of the tractor. Subject to the splintering unit, differences can be made among (Contract BiomassTradeCentre2, Manual – Wood fuels 2011): - disc splintering machines;

- cylinder splintering machines; - feeding screw splintering machines. The chips have a higher moisture than pellets and a lower gross density. Therefore chips need a longer storing period then pellets, but they are cheaper in terms of energy units (Brad 2010).

Wood pellets. Pellets constitute a new fuel, which meets the current requirements for using “clean” and renewable energy. For Romania they represent the cleanest alternative for domestic and industrial heating, seeing the alignment of the classic fuel prices to the European prices, so they will soon become the most economical and convenient alternative (http://www.proligno.ro/ ro/articles/2007/4/paper7.htm).

By definition, the pellet is a mini-briquette obtained by pressing the sawdust resulted from the log cutting technologies, from primary and secondary wood processing, from the chopped wood derived from wood waste materials, fallen trees and from other vegetal materials.

The pellets are extremely dense and can be produced with a low content of moisture (less than 10%), which makes burning possible with a high yield of combustion;

Biomass Potential in Romania Agricultural vegetal remainders

Forest exploitation remainders

Zootehnical farm remainders

Wood waste materials, sadwust

Urban domestic remaiders


in addition, their shape and sizes make automated feeding possible with a high precision (Lunguleasa 2010). Furthermore, the transport costs are lower and the storing and utilisation logistics is improved. Basically, the wood pellet becomes a viable replacer of various fossil fuels (natural gas, oil, charcoal) or of firewood.

Types of pellets: - “white” pellet: from soft wood – coniferous trees (fir tree, ash etc); till 4.000

kcal/h); it remains clean after burning, with few ash residues; - mixed pellet: the tree kinds above are used for these pellets, in combination with

those below. The mixed pellet is more difficult to find. Between 4.200 and 4.400 kcal/h; - “dark” pellet: from hard wood (beech, chestnut tree, walnut etc.). It has a

greater calorific power (4.400 kcal/h), but after burning it causes more ash residues, which calls for cleaning the equipment more often (http://www.seminee-sobe-peleti.ro/tehnologie/energie-regenerabila/energie-regenerabila-2). Wood pellets advantages. The wood pellets represent a solid environmentally friendly fuel originating from a renewable and sustainable source, used for producing heat and energy, produced 100 % from wood fibres. It is globally standardised. Pellets are neutral from the carbon emissions point of view. Upon burning, they release the same amount of carbon dioxide that was absorbed by the forest during growing. The wood pellets burn almost without smoke exhaustions. In the burning gases the dust is alkaline. They have a low content of metal and the sulphides are nearly inexistent. The ash, rich in minerals, can be successfully used as natural fertiliser. Pellets cost less than fossil fuels. The pellets price is far more stable than the fossil fuels one, which constantly rises up (http://www.protehnic.ro/images/oferta%20cazane%20peleti.pdf). Briquettes made of wooden mass. Briquetting is the process of mechanically/thermally or hydraulically compressing sawdust for reducing sizes and for obtaining a compact product with a great calorific power. The briquette shapes differ: from cylindrical to hexagonal and rectangular. The raw material that is to be inserted in a briquetting press must meet 2 essential conditions: moisture between 6 and 17% and granulation between 3 and 20 mm. Sawdust briquetting is an activity with a tremendous potential both in Romania and in the Eastern European countries.

The briquette density is a bit lesser than the pellets’, because the raw material has larger sizes also on account of the compacting-compressing coefficient. The shaping process is similar to the pellets, but at a greater scale. No adhesive is used in this process, the lignin from the wood making the particles adhere into a solid body (Lunguleasa 2010).

The advantages are first of all the fact that, unlike other fuels, sawdust is highly superior. For instance, heating needs an amount of briquettes twice smaller than of wood, because the calorific power of briquetted sawdust is 4,200-5,500 kcal/kg, as compared to that of firewood: 1,600-2,800 kcal/kg. However the greatest advantage consists in the fact that the raw material can be obtained with no difficulty.

Exploitation works. The full and superior valorisation of the wood mass called for continuing the actions of providing forest accessibility by transporting installations, the perfecting of the exploitation technologies and the extension of the mechanisation of the difficult works that suppose a great amount of work, which are specific to this industry (Ionaşcu 2002).

Generally speaking, less than 66% of the wood mass amount is taken out of the forest for subsequent processing; the remaining quantity is left on site, burnt there or used as firewood, for example chopped wood. After processing, only 28% of the tree becomes cut wood, the remainder being residues (Brad 2010).

There are two main working systems in the forest exploitation operations: - the reduced exploitation system – RES: processing is made where the trees are put down in the forest and the marketing logs undergo haulage;


- the complete exploitation system – CES: after being put down, the entire tree undergoes haulage and processing takes place either on the forest road or at the unloading place (***Contract BiomassTradeCentre2, Manual – Wooden Fuels 2011).

Depending on the nature and the origin of the wood products meant to exploitation, they fall into the following categories: main products – derived from the main arboretum by cutting operations and regeneration, secondary products – resulted from the arboretum care provision cutting operations, hygiene products, wood products originated from the exploitation of the dispersed trees that are broken, put down, dry, attacked by insects, accidental products (Horodnic 2003).

Storing the wood materials for heating purposes and the raw materials for producing chopped wood, pellets and briquettes. Biomass utilisation for heating purposes has a great potential if sources of biomass are available. Biomass utilisation needs planning at the local level and the implementation of structures for production and for getting supplies. One of the challenges at the national level is represented by the local supply with renewable wood materials. Wood material management in terms of logistics. The wood material can be stored in 3 different ways: 1 metre long block sets or in 1 cubic metre pallet boxes – for 33 cm logs, or in bulk, under the storehouse canopy.

In the open storehouse, the wood material is conditioned till it reaches a water content of less than 30%, after which it is stored covered or sold as such.

The chopped wood and the wood chips are products that result from the carved raw material after having been stored for at least six months (spring and summer), after which they get stored in the covered warehouse, too.

The determination of the moisture parameter is necessary upon delivery, the product prices depending on that (Figure 4). Subject to the product, moisture is determined in the drying chamber or by means of a portable moisture meter (***Contract BiomassTradeCentre2, Manual – Wood Fuels, 2011).

Figure 4. Determination of the wood material moisture Assessment in terms of wood biomass quality. At the European level, the European standards pertaining to solid fuels are managed by the CEN/TC 335 Technical Committee, created in 2001.

The classification of solid biofuels is based on their origin and source. The CEN/TC 335 Technical Committee has drawn up the concept of the standard that describes all the forms of the solid biofuels in Europe, including wood chips, wood pellets and briquettes, logs, sawdust and straw bundles.

EN 14961 - 1: Solid Biofuels. Fuel Specifications and Classes Part 1: General Requirements. This European standard sets up the fuel quality classes and the specifications for solid biofuels. In conformity with the authorisation granted for the standardisation activity, the scope of 335 CEN/TC only includes solid biofuels originated from the following sources: a) products from agriculture and forestry; b) vegetal waste materials from agriculture and forestry; c) vegetal waste materials from the food processing industry; d) wood waste materials, except those likely to contain halogenated organic compounds or heavy metals, as a result of the treatment with


preservatives for wood or of covering, and which include especially the wood waste materials derived from constructions and demolitions; e) fibrous vegetal waste materials from the production of virgin cellulose and from the production of paper obtained from cellulose, in case of co-incineration at the manufacturing place and where the generated themal energy is retrieved; f) cork waste materials.

The tables below present the basic indicators for chooped wood, pellets and briquettes, in accordance with the aforementioned standard (Tables 2-6).

Table 2

Chopped wood classification according to sizes - EN 14961-1 2010

Quality class

Main fraction > 80%

Fine fraction < 3.15%

Rough fractions - max. length %

P16 3.15 ≤ P ≤ 16 mm ≤ 12% ≤ 3% > 16 mm < 31.5 mm P45 3.15 ≤ P ≤ 45 mm ≤ 8% ≤ 3% > 63 mm

and max. 3.5% > 100 mm, total < 120 mm

P63 3.15 ≤ P ≤ 63 mm ≤ 6% ≤ 6% > 100 mm, total < 350 mm

P100 3.15 ≤ P ≤ 100 mm ≤ 4% ≤ 6% > 200 mm < 350 mm

Table 3 Specifications on the moisture and ash for chopped wood, as per EN 14961-1 2010

Quality parameter

Moisture Ash Class (u %) description Class (u % s.u.) M20 ≤ 20 dry A0.7 ≤ 0.7 M30 ≤ 30 adequate for storing A1.5 ≤ 1.5 M40 ≤ 40 with limited storing

possibilities A3.0 ≤ 3.0

M55 ≤ 55 A6.0 ≤ 6.0 M65 ≤ 65 A10 ≤ 10.0

Table 4

Pellet classification according to sizes - EN 14961-1 2010

Quality parameter Diameter (D) Length (L)

Class mm Class mm D06 ≤ 6 ± 1.0 mm D06 3.15 ≤ L ≤ 40 mm (95 w-%) D08 ≤ 8 ± 1.0 mm D08 3.15 ≤ L ≤ 40 mm (95 w-%) D10 ≤ 10 ± 1.0 mm D10 3.15 ≤ L ≤ 40 mm (95 w-%) D12 ≤ 12 ± 1.0 mm D12 3.15 ≤ L ≤ 50 mm (95 w-%) D25 ≤ 25 ± 1.0 mm D25 10 ≤ L ≤ 50 mm (95 w-%)

An aspect that has to be taken into account in case of using quality biomass is the application of a simplified system of quality assurance and quality control (QA/QC) for small businesses with wood biomass.

At present, in Romania there are no other schemes for wood fuel labelling/certification. The quality-related goals have been set up according to the Western standards. As far as the certification in the field of wood fuels is concerned, so far the certification has been made by using German standards - DIN 51731 (Solid Fuel Test – Compacted Wood and Compacted Bark in a Natural Condition – Pellets and Briquettes – Testing Requirements and Specifications) and DIN plus (Wood Pellets Used within Small Sized Heating Systems) or the Austrian standard ŐNORM M 7135


(Compacted Wood and Compacted Bark in a Natural Condition – Pellets and Briquettes – Testing Requirements and Specifications).

Table 5

Specifications on the moisture and ash for pellets, according to EN 14961-1 2010

Quality parameter Moisture (M) Ash (A) Mechanical durability (DU) Bulk density (BD) Class (u ) Class (u% s.u.) Class % Class kg/m3 M10 ≤ 10 A0.7 ≤ 0.7 DU 97.5 ≥ 97.5 BD550 ≥ 550 M15 ≤ 15 A1.5 ≤ 1.5 DU 96.5 ≥ 96.5 BD600 ≥ 600

A3.0 ≤ 3.0 DU 95.0 ≥ 95.0 BD650 ≥ 650 A7.0 ≤ 6.0 DU 95.0- < 95.0 min. val. BD700 ≥ 700 A10.0 ≤ 10.0 BD700+ > 700 min. val. A10.0 +

Table 6

Briquette classification according to sizes – as per EN 14961-1 2010

Quality parameter Diameter (D) Length (L)

Class mm Class mm D40 25 ≤ D ≤ 40 L50 ≤ 50 D60 ≤ 60 L100 ≤ 100 D80 ≤ 80 L200 ≤ 200 D125 ≤ 125 L300 ≤ 300

D125+ > 125 max. val. L400 ≤ 400 L400+ > 400 max. val.

Conclusions. The authors’ contribution to this paper is to set out data from the wood biomass literature. The advantages of its utilisation have taken into account quality, in the light of the European standards, some of them being already taken over at the national level.

The main advantages of the wood waste materials/wood biomass are: - to valorise the product resulted by its marketing both on the domestic market

and in exports; - to apply the quality and environment standards existing at the European level; - to make a simple alternative for producing heat in households or in manufacturing companies within the small industry; - to remove the wood waste materials from the storing platforms; - to provide efficient environmental protection; - to recycle materials; - to accelerate the alignment of Romania’s ecological legislation to the one existing in the field at the level of EU. Acknowledgements. The paper was financially supported by the project Biomass TradeCentre2 “Development of biomass trade and logistics centres for sustainable mobilisation of local wood biomass resources” (Contract IEE/10/115/SI2.591387). The project is co-funded by the EU in the framework of Intelligent Energy – Europe Programme References Budău G., Câmpean M., Coşereanu C., Lica D., 2011 Reed plant biomass as renewable

and low-polluting energy resource. Environmental Engineering and Management Journal 10(8):1053-1057.


Brad M. L., 2010 Researches on the superior valorisation of small-sized wood. PhD Thesis Abstract, Braşov.

Ionaşcu G., 2002 Wood exploitation and valorisation. Tridona Publishing House, Olteniţa, Romania.

Horodnic S., 2003 Fundamentals of wood exploitation. Universităţii Publishing House, Suceava, Romania.

Lunguleasa A., 2010 Wood briquettes versus pellets. Regent 3(30):217-222. *** EN 14961 - 1 : Solid Biofuels. Fuel Specifications and Classes. *** Contract BiomassTradeCentre2, Manual – Wood Fuels, 2011. *** http://www.scribd.com/doc/ 48088810 /Silvi-Cultura. ***http://www.bracon.ro/Produsesiservicii/Energiedinlemn/BIOMASA-avantajele_caldurii

din_lemn. *** http://www.proligno.ro/ro/articles/2007/4/paper7.htm. ***http://www.seminee-sobe-peleti.ro/tehnologie/energie-regenerabila/energie-

regenerabila-2. *** http://www.protehnic.ro/images/oferta%20cazane%20peleti.pdf. Received: 01 February 2014. Accepted: 28 February 2014. Published online: 31 March 2014. Authors: Mihaela Begea S.C. ICPE Bistrita S.A., 7, Parcului Street, 420035 Bistrita, Romania, e-mail: [email protected] Corina Michaela Berkesy, S.C. ICPE Bistrita S.A., 7, Parcului Street, 420035 Bistrita, Romania, e-mail: [email protected] Mircea Craciun, S.C. ICPE Bistrita S.A., 7, Parcului Street, 420035 Bistrita, Romania, e-mail: [email protected] Liviu Suciu S.C. ICPE Bistrita S.A., 7, Parcului Street, 420035 Bistrita, Romania, e-mail: [email protected] László Erno Berkesy, University Babeş-Bolyai, Faculty of Environmental Science and Engineering, Fantanele Str., no. 30, 400294 Cluj–Napoca, Romania, e-mail: [email protected] Mihaela Andreica, S.C. ICPE Bistrita S.A., 7, Parcului Street, 420035 Bistrita, Romania, e-mail: [email protected] This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited. How to cite this article: Begea M.,, Berkesy C. M., Craciun M., Suciu L., Berkesy L. E., Andreica M., 2014 Wood biomass - production, storing and assessment from the quality viewpoint. Ecoterra 11(1):43-50.

Documents

production, storing and - cercetare, protectie mediu, …from this type of biomass, such as firewood, briquettes, pellets, wood chips, the storing in marketing logistic centres and