Volume 22(2), 121 – 128, 2018 [610660]

Volume 22(2), 121 – 128, 2018
JOURNAL of Horticulture, Forestry and Biotechnology
www.journal -hfb.usab -tm.ro
121 Study on the evaluation of the energy potential of wood -based
biomass

Moatăr Mihaela1, Dragomir P.1, Camen D.1, Petcov Andreea1, Ștefan Carolina1, Fora C.1,
Stanciu S.2, Iancu T.2, Popescu C .4, Radulov Isidora, Băbucă N. I.3*, Ciolac Valeria4

1 Faculty o f Horticulture and Forestry, Timișoara ; 2 Faculty of Farm Management, Timișoara ; 3 Faculty of
Agronomy, Craiova ; 4 Faculty of Agriculture, Timi șoara

*Corresponding author : [anonimizat]; [anonimizat]

Abstract The use of biom ass to produce energy as a renewable raw
material with a high calorific value and a low cost production is economically
efficient and has an insignificant impact on the environment. Available in large
quantities and with current low use, biomass has a grea t potential to become
a key element in renewable energy production.
The need for energy system development, increasing energy consumption,
conventional fuel consumption and pollution have motivated states across the
globe to invest in research and developm ent of unconventional energy
systems, including: solar, geothermal, wind, biomass. The biomass resources
are numerous: biomass; plant biomass; biomass from fruits and seeds;
residual animal products, residual horticultural products, residual agro –
industria l products and end -of-life materials. Key words

biomass, development,
pellets, mass, environment

Promoting the use of biomass as an
unconventional and renewable source of fuel with a
high calorific value and a low production price is a
practical and economical way to improve energy
efficiency and protect the environment by knowing that
by burning it the impact on the environment is
insignificant (7, 9) .
General data:
Total mass (including humidity) – over 2000
billion tons;
Total land mass – 1800 bill ion tons;
Total mass of forests – 1600 billion tons;
Annual increase of biomass – 400,000 million
tons;
The need to ensure sustainable energy
development, while at the same time achieving
effective environmental protection, has prompted
intensification of the concerns regarding the promotion
of renewable energy resources and supporting
industrial technologies.
In renewable energy sources, the largest share
of energy production is held by biomass due to stored
solar energy, which can be converted into electr icity,
fuel or heat. The advantages of using biomass include
their diversity and their ability to regenerate quickly
and permanently. Wood biomass is most commonly
used knowing that the chemical composition of wood
varies very little, depending on the spec ies.
Biomass is considered to be the entire tissue
of wild or cultivated plants in the raw or processed
state and represents the biodegradable fraction of
products, waste and residues from agriculture, municipal waste, forestry and related industries.
Biom ass has a major potential as a renewable
energy source, being considered a relatively clean fuel
and reducing CO2 emissions. It has reduced sulfur
content and the amount of nitrogen and particle
emission, lower than fossil fuels. In this paper we
present t he use of solid biomass as a possible source of
energy (4). Two major advantages are achieved:
reducing production costs and reducing the
environmental impact. Biogas gasification is a thermo –
chemical process of transformation of wood biomass
into combusti on gases, and ash is eliminated during the
energy cycle.
Biomass is the biodegradable part of
agricultural products, waste and residues, including
vegetal and animal substances, forestry and related
industries, and the biodegradable fraction of industrial
and urban waste.
Biomass is the most abundant renewable
resource on the planet. This includes absolutely all
organic matter produced by the metabolic processes of
living organisms (6). Biomass is the first form of
energy used by humans with the discovery o f fire.
In some developed countries, biomass is used
quite intensively, for example Sweden, which provides
15% of its demand for primary energy sources. Sweden
plans in the future to increase the volume of biomass
used together with fossil. US 4%, where th e energy is
obtained from the biomass near the quantity obtained at
the atomic -electric stations, now operates 9000MW
total plants, where biomass is burned with the purpose
of obtaining electricity.

122

Fig.1: The land surface area used in the European Uni on in 2017

40,1% Agricultural land (24,3% arable land, 13,2% pastures, 2,5% agricultural land, 0,1% gardens) + 39,9%
other categories ;
14% forests ;
6% other categories .

Biomass with ease can provide over 20% of
the country's energy needs. In other words, existing
land resources and agrarian sector infrastructure allow
for the complete replacement of all atomic stations
without influencing food prices. Also, the use of
biomass to produce ethanol may reduce oil imports by
50%.

Material and M ethods

The material studied is represented by pellets
produced in 10 different units, which are frequently
encountered on the Romanian market. In the researches
carried out, the method of bibliographic investigation,
completed by the observation, was used as a gen eral
method of work. For the comparisons between the
technical characteristics of the pellets, the
specifications given by the manufacturer were used
Woody wastes – the main source of alternative
energy
Biomass reserves are especially wood waste,
agricultu ral waste and household waste and energy
crops. Biomass production is not only a renewable
energy resource as a significant opportunity for
sustainable rural development.
At present, in the European Union, 4% of the
energy demand is provided from biomass. At EU level,
it is estimated that approx. 300,000 new jobs in rural
areas by exploiting biomass. At present, no technology
has been developed in Romania for the complete
recovery of all wastes. For example, at present, there
are no specialized machinery fo r removing crows and
roots in our country, and t his potential for wood waste
cannot be capitalized at least in the short and medium
term. In the long run, it is necessary to carry out an
analysis to determine the opportunity to acquire the
technologies alr eady in place on the European market
for removing and capitalizing on these roots and roots,
taking into account that this practice is widely applied
in the Nordic countries of Europe and Italy. European countries apply this technology to
energy plantation s, due to the economic benefit of their
use as fuel and soil preparation considerations for
future plantations.
Pellets
A short history of pellet production is as
follows:
• 1970 – The first wood pellet production plant
is built in Brownsville, USA;
• 1983 – the first residential thermal plant in
the US is used as fuel – pellets;
• 1990 – In Sweden, industrial production of
wood pellets is started as fuel;
• 1996 – there were already more than 20
producers of thermal power plants and more than 80
pellet pro ducers. More than one million tons of pellets
are already heating homes in North America;
• 1997 – there were already over 500,000
pellet -based thermal power plants in North America.
The term "pellet" usually designates a small
piece of material, usually c ylindrical, obtained by
compressing an original material. Pellet production
began in the United States in the after World War II.
During the production process of the pellets, the 100%
natural raw material (sawdust and wood chips) is
pressed under high pre ssure without the addition of
synthetic adhesives, the resulting product being small
rods. The necessary adhesive is lignin in wood, but it is
often used for this purpose different oily seeds, certain
types of flour, which increase the solidity of the
product. Pelletizing is a mechanical pressing of the
material at much smaller dimensions and with much
higher density. Pellets are solid fuels with low moisture
content, obtained from sawdust, wood chips, or even
bark, wood chips and wood dust from industrial wood
processing plants, as well as from unused trees in forest
exploitations. The resins and binders naturally
occurring in sawdust have the role of keeping pellets
compact and therefore they contain no additives.
Wood pellets are environmentally friendly,

123 economical and neutral fuels for CO2 emissions,
mostly produced from sawdust and wood scraps, high
pressure tablets without gluing additives. They are
cylindrical, typically measuring between 6 -10 mm in
diameter and 10 -30 mm in length. Being a high -grade
and compressed fuel, the pellets allow their transport to
be economical and use fully automated systems in
power and heat generation units, from those serving
one family to the public. With a rapid development of
the market segment, they are the key techno logy for
increasing the use of biomass in Europe and around the
world. Pellets are also an excellent way of using local
resources and contributing to preserving the
environment and preventing climate change.
Classification of pellets
In terms of raw materi al origin, pellets are
divided into two main categories:
• Wood biomass pellets (sawdust, wood chips,
tree bark, branches);
• Pellets from agrarian waste (straw, cocoons,
sunflower husks, leaves, forest litter);
Pellets are considered an efficient source o f
heating for homes and water, with wood debris
representing less energy than that obtained from
traditional fossil fuels (carbs or oil). They are eco –
fuels, because they contain no dangerous substances
and emit less CO2 than coal or oil.
Unlike firewood, pellets have a calorific
power of 1.5 times and 1 kilogram of pellets has an
energy output of 4.8 kWh. Sweden is among the top
European countries using pellets, with about 1.4
million tonnes / year. Italy follows with 550,000 tons
of pellets / year, German y with 450,000 tons / year and
Austria with 400,000 tons / year. All these figures can
be increased by collecting wood waste resulting from
processing, as well as by introducing energy crops and
then by further processing them to convert raw biomass
into a standardized form of energy.
Characteristics of quality pellets:
Granularity: 6 – 10 mm
Length: 50 mm Heat output 4.8 – 5 kWh / kg
Humidity: maximum 12%
Ash: Up to 1% maximum content
Weight: 650 kg / mc
Pellet quality check:
The most common method is to p ut a small
amount of pellets in a glass of water (1, 8) . Good
pellets will retain their shape for a longer period. If the
pellets immediately dissolve in water, then the quality
is doubtful. Qualitative pellets are smooth and hard to
touch. The pellets tha t break into the touch have high
humidity and will have reduced combustion efficiency.
Qualitative pellets leave as much as 4% ash after
burning. The ash remaining is a good fertilizer for
plants. The large amount of ash left after burning
indicates the po or quality of the pellet.
Quality classes of pellets
For the pellets there are 3 classes of quality:
A1, A2 and B class. Mainly, these classes are
differentiated by dimensions (maximum length 40
mm), the maximum percentage of powders or elements
with a len gth of less than 3,15 mm (≤ 0.7% for class
A1 and ≤1.5% for class A2), the full combustion
temperature (≥ 1200 ° C for the class A1 ≥1100 ° C for
class A2).
Quality class A1 (also called premium quality)
is the most commonly used, being consumed especially
in the residential sector for burning in stoves and
individual pests, producing the lowest amount of ash,
and most importantly, the highest calorific value.
Quality class A2 is used for burning in larger
plants and produces a higher amount of ash.
Class B , also called the "industrial" class,
produces the highest amount of ash, can even contain
impurities (sand, etc.) with a significantly lower
calorific value than that of the A2 class. For this
quality class, EN Plus certification is not required.
Dependin g on the use of stoves or boilers
(residential or industrial), manufacturers and installers
strongly recommend the use of EN Plus certified
pellets.

Example of EN Plus A1 Example of EN Plus A2 Example of EN Plus B
certification (Romanian Manufactured) certification (Romanian Manufactured) certification (Romanian Manufactured)

Fig. 2: Pellet Quality Classes

The European standard EN 14961 -2 has
established the quality requirements for pellets for the
award of the EN Plus certificate. EN plus certifies manufacturer quality, but
also checks for merchandising and logistics. This
ensures a continuous quality check and transparency

124 from the manufacturer to the final consumer. For
consumers, the new system offe rs several advantages:
among others, it ensures a strict burning process.
Generally, a pellet manufacturing line consists
of:
• Crushers or crushers for biomass;
• Mixers;
• Pellet driers;
• Pellet presses; • Automatic packing machine;
Shredders = for biom ass as well as mixers are
machines that are used to uniform wood waste. They
are usually fitted with a hydraulic feed system made up
of steel tooth discs that provide the guided transport of
wood to the cutting knives. The chopper allows control
of the fee d rollers that can be turned on or off in both
directions and produces very unifo rm wood fragments
due to the 90 ° cutting angle.

Fig. 3 Shredder

Dryers pellets are used to dry the chopped
material but must have a moisture content of less than
30% fo r classical driers or less than 50% for rotary
drum dryers. In the rotary drum dryer, the strong hot
air feeds the chopped material into the suspension to
dry it.
Due to the high velocity of the air flow and
the fact that the chopped material is in suspens ion, the transfer surface between the air and the solid material
is high, so a high rate of heat transfer results. The hot
air generator is a wood -based or coal -fired furnace but
can also be fitted with a gas or liquid fuel burner. The
wet chopped material is dried within minutes and is
further transported by means of a centrifugal fan.

Fig. 4 Pellets d ryer

Presses can also be used in households, farms,
production units, for granulation of feed for the
population or for the recycling of various materi als and
their transformation into pellets having a higher calorific value than the raw material used or can be
combined with shredders and dryers to form complete
pellet product lines.
Pellet presses are machines that use power

125 motors that roll metal rolls that press the chopped
material on a hole matrix (2,3, 5,10) . After pressing
through these holes, the raw material is compressed
and forms a compact mass that takes shape, the
diameter and the length of the mould hole. Due to the
temperature of about 70 -80 ° C due to friction, the
fibres in the raw material are joined together and plasticized so that the pellets have a rather tough
consistency. The moulds can have two different planar
and circular shapes, thus generating two different
depression patterns: flat die presses and circular die
presses each of these models having advantages and
disadvantages.

Fig. 5 Pellet press

Results

Companies producing biomass -pellets that
were studied in the study:
1. Ameco Renewable Energy SRL
2. EcoPellets SRL -Sibiu
3. ECOLEMN PRODUCTS SRL
4. Gross Handel SRL
S. S. ATHOS -PELLET S.R.L.
6. BADGER PELLETS
7. PELLETS MANDI SA
8. VISCARDS BENOIT
9. ECoB
10. Bertarelli Savino & C. snc

Below are the technical characteristics of the
pellets produced by the companies unde r study
Ameco Renewable Energy SRL
He is a Romanian producer. At the point of
work in Gheorgheni pellet production takes place,
production capacity reaching 3 tons per hour, in the
case of lighters at 0.7 tons per hour.
Technical specifications:
• Neutral CO2
• Natural material
• No artificial substances
• Diameter 6mm
• Heat power 4500 -4700 kcal
• Length 15 -30mm • Humidity 6%
• Ash <0.6%
EcoPellets SRL -Sibiu
Ecopellets is a Romanian producer dealing
with the processing of biomass resulting in the main
wood pellet. The factory is located in Sadu village,
punctual working "La Mal", Sibiu County , Romania.
Ecopellets is a founding member, along with other
producers in the country, of the Romanian Wood
Production Association -Eco Energia.
Technical specifications :
• Diameter 4 -10mm
• Length <50mm
• Humidity <8%
• Ash <1.5%
• Heat power 4300 -4500 kcal
ECOLEMN PRODUCTS SRL
The Caransebes plant is the only one that
produces hardwood pellets, benefiting from the highest
technology in the field and with a production ca pacity
of 50 to 100 tons daily. The resins and binders
naturally occurring in sawdust have the role of keeping
pellets compact and therefore they contain no
additives.
Technical specifications:
• Diameter 4 -10mm
• Length <50mm
• Ash content <1%
• Heat powe r 3900 -4100 kcal

126 Gross Handel SRL
Pellets are made from clean and untreated
sawdust. This material is first dried, then crushed and
compressed (without adhesives or glue) until it
eventually becomes final. This makes it a "green fuel",
a 100% natural fuel.
Technical specifications:
• Dry matter <92%
• Ash <0.5 -1%
• Heat output 3800kcal
• Humidity 10 -12%
• Diameter 6 -8mm
• Length – max 4 * diameter
S.C ATHOS -PELLET S.R.L.
The main activity of our company is the
production of sawdust wood sawdust.
Technical specifications:
• Diameter: 8mm
• Length 10 -25mm
• Humidity 8%
• Ash 0.95%
• Caloric power 4500 -4600 kcal
BADGER PELLETS
The company produces the highest quality
pellets using at the same time processing and
production technologies that are respected to th e
environment. Wood pellets are wood -based and do not
have a chemical binder.
Technical characteristics:
• Diameter 6mm
• Length <30mm -45mm
• Humidity <10%
• Heat power 3900 -4200 kcal
• Ash <0.7%
PELLETS MANDI SA
Pellets produced 100% of softwood species.
Technical characteristics:
• Length 1 -4 cm
• Diameter 6mm
• Density 1.1
• Heat power 4000 -4200 kcal
• Humidity <8% • Ash <0.7%
VISCARDS BENOIT
Produces oak pellets are available in 15 kg
bags or bulk. In addition to other manufacturers, they
sell very larg e pellets with great energy performance
ideal for domestic heating stoves.
Technical features
• Length 8cm
• Diameter 7cm
• Humidity 4%
• Heat power 4800 -5000 kcal
• Ash 1%
ECoB
The pellets are produced 100% of softwoods
with a combustion efficiency of 98. 7%. Pellets are
available in a bag or bulk.
Technical features
• Diameter 6 -8mm
• Length 10 -25 mm
• Humidity 5%
• Ash <1%
• Heat power 4800 -4900
Bertarelli Savino & C. snc
Produces 95% certified beech and oak wood
pellets and the rest of 5% of maple, ash a nd aspen.
Technical features
• Diameter 6mm
• Ash 0.46%
• Humidity 5.28%
• Density 635kg / m3
• Heat power 4600 -4700

Moisture of pellets
In order to more easily compare the energy
potential of wood biomass, we have introduced all the
graphical data from w hich we can easily observe the
technical characteristics sought and offered and their
price.
Minimum Humidity: 4% (Company –
VISCARDY BENOIT)
Maximum Humidity: 12% (Company –
ECOLEMN PRODUCTS SRL and Gross Handel SRL)

0 5 10Ameco Renewable Energy SRlEcoPellets SRL sibiuECOLEMN PRODUCTS SRLGross Handel SRLS.C ATHOS -PELLETS S.R.L.BADGER PELLETSPELLETS MANDI SAVISCARDY BENOITECOBATIBertarelli SavinoC. Snc

Fig.6 Mois ture value of the pellets

127 Ashes of pellets
Ash is the product of pellets and is composed
of non -combustible inorganic substances, such as mineral salts. The ash remaining is a good fertilizer for
plants.

AMECO RENEWABLE ENERGY SRl
ECOPELLETS SRL SIBIU
KONTRASTWEGE SRL
ECOLEMN PRODUCTS SRL
S.C ATHOS -PELLETS S.R.L.
BADGER PELLETS
PELLETS MANDI SA
VISCARDY BENOIT
ECOBATI

Fig.7 The amount of a sh resulting from combustion

Minimum ash: 0.25% (Company – S.C
ATHOS -PELLET S.R.L.)
Maximum Ash: 1.5% (Company – EcoPellets
SRL-Sibiu)

Conclusions

Advantages of pellets :
• They are ecological. It does not pollute the
atmosphere;
• They are modern; they are cheap (compared
to electricity or gas) ;
• Higher self -sufficiency (against wood).
Depending on the size of the tank, the autonomy can be
several days to a few weeks even on larger tanks;
• They are made from wood waste. It is
produced from dry biomas s with extrusion special
presses. It can also be made of sawdust, wood waste,
branches, balloons, straw, agricultural waste.
• Emit low smoke during burning ;
• Low sulfur and metal content ;
• The resulting ash can be used as fertilizer ;
• Better yield (com pared to wood) ;
• Operating cost close to gas or lower by 10 –
25%;
• They are safe in operation. They are not explosive, toxic or polluting. During combustion, the
amount of oxygen required is very low compared to
other fuels.
• Convenient operation. If you do not want to
be a wood boiler, the version of a pellet boiler is an
alternative that gives you comfort and autonomy.
• Aesthetics and design. You can use stoves or
fireplaces that can be installed in any room .

Disadvantages of pellets :
• The cost of th e wood power plant is high
(compared to a gas boiler or an electric boiler) ;
• The boiler is sensitive to pellet quality and
must be cleaned periodically ;
• Technical chamber and chimney are
required ;
• To protect against current interruption,
separate equ ipment must be: UPS uninterruptible
power supply or power generator ;
• Have a chimney ;
• Choose the cheapest pellets usually, which
may be of poor quality and can damage the thermal
plant
Of the ten pellet production companies
compared in previous graphs, it can be seen that the
most cost -effective pellet (following the price / quality
ratio) is the one produced by VISCARDY BENOIT

128 with the lowest humidity, the highest calorific value
and the content of ash below 1% at a price of 135 € +
VAT / tonne.

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