Environmental aspects of the pure plant oil use
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he EU Directive on stimulation of use of energy from renewable sources (DIRECTIVE 2009/28/ES) stipulates for Slovenia that it is liable to reach, till 2020, at least 25% share of energy from renewable sources. By 2020, the share of biofuels
should amount to 10%. The average production of rape seeds in Slovenia amounted to 2.4 t/ha (SORS, 2009). Pressing
3 tons of rape seeds yields ca. 1,000 litres of oil suitable for further processing into high quality edible rape oil or ca.
1,000 litres of pure plant oil suitable for the propulsion of vehicles. This roughly means that on a hectare large plot of
land ca. 1,000 litres of pure oil and ca. 2 tons of rapeskins (left after the plant oil pressing) for fodder can be produced.
In average Slovenian conditions, 767 litres of pure plant oil can be produced on average from 1 ha of rape. By using it
for the propulsion of tractors, the emissions of CO2 can be reduced by 2,055 kg, while rapeskins are considered a high
quality alimental supplement for fodder.
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© 2011 | Layout: tsw.co.at;
he oil produced through rape seed pressing at the Agricultural Institute of Slovenia is used for the propulsion of 2
tractors adapted for pure plant oil drive (Agromehanika AGT 835 and Fendt Favorit 614 LSA), a Land Rover field vehicle,
and a stable engine. The tractors and Land Rover are in regular use. Pure vegetable oil is also used for the propulsion of
a stable 26 kW engine with electric generator. In this case, the cogeneration system is also developed – coproduction of
both electric and thermal energy.
Gozdarski inštitut Slovenije
Kmetijski inštitut Slovenije
dr. Nike Krajnc
Department of Agricultural Engineering
Večna pot 2, 1000 Ljubljana
Grajska cesta 1, 1234 Mengeš
[email protected]
[email protected]
www.gozdis.si
www.kis.si
www.agriforenergy.com
PRODUCTION AND USE OF PURE
VEGETABLE OIL IN JABLE
Environmentally friendly – independent – local
Loka pri Mengešu, Slovenia
The contents of this publication are full responsibility of its authors and do not necessarily reflect the opinion of EU member states. The European Commission is not
responsible for any potential use of information published in this publication.
Authors: : dr. Viktor Jejčič in mag. Tomaž Poje, dr. Nike Krajnc, Tine Premrl; Editor: dr. Nike Krajnc; Published by: Gozdarski inštitut Slovenije, Založba: Silva
Slovenica; Translated by: Henrik Ciglič; Technical Editor: Robert Krajnc, Photos: arhiv LK-Stmk, arhiv KIS, Tomaž Poje
The publication has been co-financed within the framework of IEE/08/600 - AGRIFORENERGY 2
Print: BIROGRAFIKA BORI d.o.o., 2012, Circulation: 200 copies
GOOD PRACTICE EXAMPLE
Idea of the project
For centuries, mankind has been producing plant oils through
The organisational model
The Jable oil mill operates within the framework of the Agricultu-
the procedure of their mechanical extraction from seeds or fruits
of various oil-containing plants. Apart from its basic alimental
purpose, oil served for lighting purposes, production of paints
and lubricants, cosmetics, etc. The increasing ecological problems as well as the ever-increasing need for energy have made
oils of different plants exceptionally interesting as raw material
for the production of biodiesel or for direct use as a fuel.
ral Institute of Slovenia, Department of Agricultural Engineering. It
functions for the needs of the Agricultural Institute of Slovenia itself, at the same time offering its services of pressing different oleaginous plants for both natural and legal persons. External pressing services take place predominantly in the sense of testing
individual oleaginous plants brought to the mill by other research
institutions. If merely bare pressing is carried out, the oil mill is led
by a professional associate, while in the event when pressing is
implemented for research purposes an engineer is present as well.
For the needs of the Agricultural Institute of Slovenia, Department
of Agricultural Engineering, greater quantities of seeds are pressed
for the production of oil for experimental purposes (varying of different operational parameters of the press as well as varieties of
seeds for pressing), of oil as fuel for two tractors, a field vehicle and
a stable engine, and for the propelling of the cogeneration unit.
Special pressing of oleaginous plants is also carried out, when
yield of separate plants or varieties is ascertained.
Today plant oils serve for alimentary, pharmaceutical, and technical purposes (oils for lubricating saw chains, oils for hydraulic
appliances, oils for the production of biodiesel, oils for direct
energy use, etc.).
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roduction of oils as propellants for modified diesel engines
takes place on the basis of extraction of oils with the aid of mechanical pressing or with the aid of solvents (ecologically questionable, in use in large industrial plants). Mechanical seed pressing is mostly implemented with mechanical continuous presses
of screw type. With regard to raw materials temperatures, cold
and hot press procedures are distinguished. In the first procedure, the starting material‘s temperature is up to 25˚C, while in the
latter procedure, the raw material‘s temperature is above 25˚C.
The decentralised oil production can be carried out by farmers,
mechanical engineering interest groups, small firms, schools, etc.
They can produce oils for energy purposes, when food for animals (oil-cakes) is made at the same time. Domestic edible oils
(e.g. on tourist farms for richer supply of their own products) can
also be produced, as well as oils for pharmaceutical purposes, etc.
Thus a higher income is provided, or a higher added value is created on farm.
Time course of the project implementation
Initial idea ..................................................................................... spring 2005
Planning of the project .......................................................................... 2007
Implementation of the project ..........................May-September 2007
Building of the cogeneration unit ...................................................... 2009
Beginning of the entire line-up operation ................November 2009
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he economy of oleaginous plant pressing is strongly influenced
by the sale and use of by-products left after the pressing of oil
(their use varies in relation to the species of oleaginous plants).
For example, when pressing rape seeds, the pressing by-product
(pellets and oil-cake) is a protein rich fodder.
Above the press, storage for continuous inflow of seeds (gravitational supply) is situated. The oil arriving from the press is cleared
of rough admixtures in a smaller container, from which the oil is
conveyed into a larger oil reservoir with the aid of centrifugal
pump. For a continuous removal of pellets, screw conveyor is
used. Pellets are stored in dry and airy storage.
I
n the Jable oil mill, a combination of both purification methods is
utilized. Oil is left in sedimentation containers (combined vessels
with flow-through pipes) for a period from a few days to a few
weeks or even a whole month. Oil is poured into sedimentation
containers continuously and slowly. At a certain percentage, sediments can be added to the oil-cake or pellets. In the mini oil mill,
oil is also purified with the aid of filtration (Rover‘s flat filters). The
principle of purification with the aid of filtration is based on letting the oil with impurities through filter elements that retain mechanical parts in the filter‘s pores.
Delivery of the fuel
For the needs of the Agricultural Institute of Slovenia, rape seeds
are grown during the so-called variety trials as well as in a normal
process. If necessary, seeds can also be bought on the free market.
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Supply of seeds into the press
Technical data
The Agricultural Institute of Slovenia,
Department of Agricultural Engineering, has been continuously engaged
both in rational use of energy in agriculture and in renewable sources of energy
stemming from agriculture. By acquiring various projects on the subject of
biodiesel and pure vegetable oil as a
propellant for diesel engines (tractors),
they began to ponder over constructing their own mini oil mill.
The very first ideas about it were brought forth in 2005; they were
followed by a plan and actual making of the first press. On the
basis of this press, an improved version was developed, which
has been in use since 2007. In that year, the entire oil mill was
completed with automatization of the seed supply to the press
system as well as with sedimentation and filtration of the pressed
oil. The Jable oil mill is located in the Department of Agricultural
Engineering at the Agricultural Institute of Slovenia, Grajska cesta
1, Jable, Loka pri Mengšu.
rious oleaginous seeds. The press performs continuous cold pressing of oleaginous seeds (no special heat for heating the seeds or
machine needs to be supplied for the working process). Furthermore, no special supervision of the machine during the pressing
process is needed. During this process, oil is continuously removed from the pressure and led to a special pre-filtering reservoir,
where rough purification of oil from mechanical particles is carried out. At the same time, oil-cake is formed as a by-product of
the pressing procedure.
Pressing capacity .................................................................................50 kg/h
Production of oil from 1kg of rape seeds ...................................... 0,4 kg
Press motor power ................................................................................2,2 kW
Seed storage capacity.................................................................................. 5 t
Oil purification ............................................sedimentation and filtration
Recommendable tem. of seed at the entry into the press .........20oC
The press used for continuous pressing of rape seeds; maximum pressing
capacity amounts to 50 kg/h, subject to the seed variety; the hourly effect
can be doubled with a serial connection of another press
Technology
Pressing can be one- or two-phase process. In the latter process,
up to 40% of oil can be pressed from rape seeds. With a well functioning press, 0.4 kg of oil and 0.6 kg of oil-cake (used as fodder for
domestic animals) can thus be obtained with two-phase pressing.
C
old pressing of oil has a great advantage over other production
processes that are currently in use for the production of oil, except
that this procedure is accessible practically to a good number of
users. For cold pressing, no exceptionally demanding and expensive machines used in industrial extraction of oil are needed. The
mechanical pressing procedures are characteristically simple, continuous (with no special control required) and in no need of greater amounts of energy.
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he basis of oil mill is mechanical screw type press. It is intended
for the extraction of oil with the aid of mechanical pressing of va-
T
he press is composed of the following parts: screw for the conveying and pressing of seeds, pipe with holes through which oil
is extracted, and pressing head with sleeve through which
pressed seeds in the shape of pellets are extracted. On the upper
part of the pressing pipe, the pyramid-shaped stowage mouth
for oleaginous seeds is attached. The seeds gravitationally travelling from the stowage mouth reach the horizontal screw, which
conveys them, through rotation, to the pressing head, where
seeds are pressed. Oil is returned in the opposite direction to the
rotation of the screw and flows through the holes in the pipe. The
pressed seeds, on the other hand, are pushed by the screw from
the pressure head through the sleeve, where they are formed into pellets. The front part of the pipe with holes is covered by protector to prevent oil squirting out. The press is powered by 2.2 kW
electric motor. The entire pressing and driving part is attached to
the carrying frame, which is equipped with oil reservoir. In the
latter, the oil is partially purified through the sedimentation process. On the reservoir, a display is located on which the quantity
of oil in the reservoir itself can be read.
maller quantities of seeds are stored in the place where the
press is located, in order for them to reach room temperature. Larger quantities, on the other hand, are kept separately in a special
storage (with 5 t capacity). The seeds‘ moisture content, which
should range between 6 and 9%, is of great significance as well.
They must also be cleared of any admixtures (weed seeds, pieces
of hay, small stones, soil, etc.). At the entry to the press‘s stowage
container, a special net is located, where larger particles are removed, as well a magnet for the removal of metal objects that could
damage the screw of the press. The quantity of impurities in the
seeds may reach up to 2%. For the cleaning of rape, sieves with
holes ranging from 2.2 to 2.5 mm in diameter are recommended.
Best results of rape pressing are achieved when the temperature
of seeds at the entry to the press oscillates around 20˚C.
Pressing of rape seeds yields ca. 1/3 of oil and 2/3 of oil-cake.
When filtered, the oil is used for the propulsion of reconstructed
tractors, while oil-cake is suitable as fodder.
Financing
The investor in the oil mill is the Agricultural Institute of Slovenia.
The oleaginous seed press is the fruit of development section in
the Department of Agricultural Engineering of the Agricultural Institute, whereas the manufacture of the key parts of the press was
entrusted to the specialised subcontractors. The temporary storage and conveying of seeds to the press system is a serial product
by a domestic manufacturer.
Investment cost structure
Press for the pressing of oleaginous plants ................................4.000 €
System for the temporary storing and conveying of seeds ..3.000 €
Filtering system .....................................................................................2.000 €
Total costs................................................................................................9.000 €
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he Agricultural Institute of Slovenia set the basic price for pressing external clients‘ rape seeds at 100 EUR/ton of seeds. The price of this service is
not fixed, but depends on the quality, moisture content etc. of seeds and
varies case to case.