Possibilities of using olive kernel wood for power generation on Crete –
Greece
John Vourdoubas, TEI of Crete,
Department of Natural Resources and Environment
3 Romanou Str., Halepa, Chania (73133), Crete – Greece
e-mail: gboyrd@tee.gr
Abstract.
Solid biomass has been used in many countries for power generation or for
cogeneration of heat and power. In Greece, where the olive tree is cultivated, during
the processing of the olives the Olive Kernel Wood is produced. It has a high heating
value and measures up to a very good fuel for heat or power generation. Today, it is
used extensively on Crete for heat production; in the future, it has very good prospects
for being used in power generation and/or heat and power cogeneration. Since a large
proportion of power on Crete is generated today from wind energy, it is likely that, in
the future, biomass will also contribute to the generation of green electricity
Key words: biomass,olive kernel wood, power
Introduction
Today on Crete, various renewable energy sources are used for power
generation, such as:
 Wind Energy
 Solar Energy (Photovoltaics)
 Hydropower
 Biogas (But not Solid Biomass)
Biomass can be used for heat production, for power generation or for the production of
vehicle fuels.
Today in Greece, Solid Biomass is used mainly for heat production, in
conjunction with combustion technologies. Although in other European countries Solid
Biomass is used for power generation or for cogeneration of heat and power, this is not
happening in Greece at present. Solid Biomass Combustion is a mature technology with
numerous advantages. Although the efficiency from the solid biomass combustion
process is low, the solid biomass gasification, which is derived from the combustion
process, has a very high efficiency value. Soon, this too will adhere to many
applications.
The Olive tree is cultivated in many areas of Greece. During the processing of
the olives, Olive Kernel Wood is produced. It has a significant heating value, is easily
handled and its price, in relation to its heating value, is rather low. Thus, the Olive
Kernel Wood is an attractive and lucrative option for producing fuel for various
applications. Considering that Greece, the berth of the olive tree, imports oil in order to
cover its energy needs, it is logical to derive energy from the Olive Kernel Wood, which
is a local Renewable Energy Source. The generation of energy from the Olive Kernel
Wood also has environmental advantages because its impacts to the Greenhouse Effect
are neutral. Presently, Olive Kernel Wood is used for heating buildings, greenhouses
and factories. It has positive prospects for being used for power generation and/or for
heat and power cogeneration on a wider scale in Greece in the near future.
The production of olive kernel wood on Crete
The Olive tree is currently cultivated extensively on Crete, where a perfect
quality of Olive Oil is produced. Olive Kernel Wood is produced during the extraction of
the Olive Kernel Oil. During the production of Olive Oil, a semi-solid paste containing oil
is produced. A second quality Olive Oil can be extracted from this in medium-sized
plants and the Olive Kernel Wood is produced as a by-product. The total annual
production of the Olive Kernel Wood on Crete is 110.000 tn. The Olive Kernel Oil
processing plants operate seasonally every year from November until April.
Table 1 presents the current production of Olive Kernel Wood on Crete. The flow
diagram depicting the production of Olive Kernel Wood is presented below. Part of the
produced Olive Kernel Wood is used at:
a) The Olive processing plant for the production of hot water
b) The Olive Kernel Oil production plant for the drying of the paste
The energy value of the Olive Kernel Wood produced today on Crete is equivalents to
the 21,09% of the total power consumption on the island. The overall potential from
the total produced Olive Kernel Wood today on Crete (with combustion) is 97 GWh/
year.
Table 1. Production of olive kernel wood on Crete
Prefecture
Olive Kernel Wood (tn/ year)
Chania
32,110
Rethymnon
13,890
Heraklion
16,766
Lasithti
16,272
TOTAL
109,038
Current Uses of Olive Kernel Wood on Crete
Olive Kernel Wood is mainly used for heating purposes today on Crete for:
a) Houses
b) Greenhouses
c) Various small-sized industries
Its heating value is 3500-4000 Kcal/ kg (with a moisture content of 12%) and its
price is approximately 0,05 Euros/ kg; thus, it is a very attractive option as a fuel in
comparison to oil. Olive Kernel Wood, however, has not yet found applications in power
generation or cogeneration of heat and power in Greece. Because it can be easily burnt
and the combustion technology is well known widely, it can be used as a solid fuel for
power generation in the future. Presently, it is used in houses and in greenhouses for
the production of hot water. Also, it is used in various industries for drying purposes
and/or for the production of hot water. Greece exports small quantities to other
European countries each year, where Olive Kernel Wood is used for fuel. The required
machinery for the Olive Kernel Wood combustion is the boiler( including the burner),
which is quite simple to use and not expensive. These boilers are reliable and made
locally.
Olives
Processing
Olive Oil
Liquid Wastes
Drying
and
Extraction
Olive Kernel
Wood
Olive Kernel Oil
Fig. 1. Production of Olive Oil, Olive Kernel oil and Olive Kernel Wood from Olives
to the Factory
Paste
containing
Oil
Olive Kernel Oil
Processing Plant
Olive
Kernel
Oil
Combustion
Olive
Kernel
Wood
P
O
W
E
R
to the Grid
Fig.2. Power generation from olive kernel wood
Olive Kernel Wood can be used for power generation or cogeneration of heat and
power on Crete, since it presents many advantages, such as:
1. There is no need for harvesting of raw materials and transport of them
because it is produced in the Olive Kernel Oil processing plants.
2. Its moisture content is very low and its heating value is high.
3. Its price is rather low in comparison with its heating value.
4. The combustion technology is well known. Since it is granular, either fixed bed
reactors or fluidized bed reactors can be used.
5. The generated power can be consumed either inside the plant or can be sent
to the grid.
6. The Greek Government offers good subsidies for investments in the field of
Renewable Energy Sources and, of course, in Biomass.
7. The use of Biomass for power generation on Crete will reduce the CO2
emissions on the island.
8. In the case that such a plant should be created, various other solid agricultural
residues can be used with the Olive Kernel Wood as raw materials.
9. The creation of such a plant will help in the generation of power to and from
small-decentralized plants instead of larger centralized power plants that exist
today on Crete.
10. The sulphur content of Olive Kernel Wood is minimal.
11. The efficiency of small-sized combustion plants is very low. The Olive Kernel
processing plants operate seasonally. The produced heat from Olive Kernel
Wood should be used at the time that cogeneration of the heat and power is
obtained (during its operational period which is from November – April), or
outside the plant for nearby heat-requiring operations.
12. Initially, the price of the Olive Kernel Wood will rise, due to an initial local
deficit of this Biomass source.
Table 2 shows the characteristics of a power plant on Crete consuming Olive Kernel Wood as a
fuel.
Table 2 Characteristics of a power plant consuming olive kernel wood as a fuel on Crete
NOMINAL POWER
3 MW
Operating hours/ year
8000 hours/ year
Energy generation
24,000 MWH/ year
Plant efficiency
20%
Olive Kernel Wood consumption
27,180 tn/ year
Heating Value of the Olive Kernel Wood
3800 Kcal/ kg
Capital Cost of the plant
Euros
4,8
million
Subsidies (40%)
1,92 million Euros
Cost of Olive Kernel Wood/ year
year
1,359,000
Consumption of Olive Kernel Wood in the plant
CO2 emissions which are avoided
Energy generation from the plant as %
of total Energy Consumption on Crete
Euros/
3,4 tn/ hour
29,137 tn/ year
1,04%
Conclusions
 Olive Kernel Wood is produced in large quantities on Crete, Greece as a byproduct of the Olive Oil producing industry.
 It is used at the moment for heat generation in buildings, greenhouses and in
industries; however, not for power generation.
 Since its heating value is high and it does not need any harvesting or transport,
it can be used for power generation by combustion.
 The price of Olive Kernel Wood at the moment is rather low in comparison to its
heating value.

Olive Kernel Wood is granular and it can be easily burnt. There is no published data
about its gasification, which is an alternative and more efficient method for generating
power from it.
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