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Wood pellets are clean, carbon dioxide neutral and suitable fuel which is produced mainly by sawdust and waste, pressed under high pressure without gum or other supplements. The wood pellets are of cylindrical shape and normally their diameter is 6-10 mm and their length is 10-30 mm. Due to this fact, the wood pellets are highly standardized and pressed, which allows for reduction of transport costs; they, also, assist the automated operation of heating and power plants, regardless of whether they are in one-family houses or are large power facilities. Due to their rapidly growing share in the market, wood pellets are a considerable resource for the growing utilization of the biomasses in Europe and in other regions. They are, as well, an excellent instrument for local resources utilization, because, in material aspect, they contribute to environmental protection and control of climate changes. European Union has set itself the task of increasing the share of recycled energy sources for heat and electric power generation. Biomass plays a strategic role in the achievement of such tasks, as particularly wood pellets appear to be a key technology with some specific advantages. The wood pellets can be transported more cheaply and more easily, because of their high density, compared to other biomass forms, while, on the other hand, the high degree of standardization provides for exclusively low fuel emissions, even if wood pellets are poorly used. The wood pellets are also a very convenient fuel form for end users – they can be delivered by cistern-trucks or in bags and they are suitable to be used in automatic feeding systems, which makes them convenient for processing and time-saving, same as the systems, operating with gas or liquid fuels. |
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The pellet boilers are used for the heating of bigger areas – houses or industrial building sites and they have to be connected to the relevant heating system. Their nominal capacity varies from 5 – 2.500 kW up to 85 – 95% efficiency.) For comparison, a house with an area of 80 – 90 m2 or 200 – 225 m3 heating volume needs an installed capacity of minimum 4,5 – 5 kW to heat the areas that need to be heated.
The boiler is completely automated, equipped with a special pellet burner, and the installation can also be completed with a little fuel reservoir. Moreover, a special hopper for the storage of bigger quantities of pellets can be constructed on-site (for example stock for the entire heating season). |
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It is possible existing conventional boiler (liquid fuel, gas) to be reconstructed through replacement of the burner with burner for pellets and/ or energy chops (wood chips). In this case, the investment expenses are much lower, because the required heating installation and infrastructure are already constructed and they can be used. The prices of pellet boilers vary depending on the type and power, but considering the existing correlation between the prices of the different fuels at the moment (for example, heating with pellets at equal conditions is with 40% cheaper than heating with liquid fuel, and at the same time has all the advantages - automated feeding of the fuel and small quantities of ash/waste from the burning), the difference between the prices of the liquid fuel boilers and the pellets, would be compensated within a one-year period.
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Model cost estimate for heating of industrial building site with an area of 720 m2 – dimensions 60 m. x 12 m. 2.70m. (2000 cubic meters):
- Expected power of the heating generator: 60 kW;
- Heat release by means of hot air generator, connected to existing water circulating installation or ventilation system;
- The heat generator is equipped with electric control board, which enables the programming of different periods and operating temperatures;
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Comparative table with average values for heating residential area of 100 sq.m. (270 cubic meters) |
Fuel |
Unit |
Unit price, incl. of VAT |
Released power during burning
( kW ) |
Price for kW power
( BGN/kWh ) |
Approximate heating area
(cubic metres) |
Average monthly costs |
Firewood |
kg |
BGN 0,15 |
3,00 |
0,05 |
270 |
BGN 129,60 |
Wood pellets |
kg |
BGN 0,30 |
5,00 |
0,06 |
270 |
BGN 155,50 |
Natural gas |
cubic metre |
BGN 0,70 |
9,59 |
0,072 |
270 |
BGN 186,60 |
Naphtha |
litre |
BGN 1,90 |
9,90 |
0,19 |
270 |
BGN 492,50 |
Propane-butane |
litre |
BGN 1,00 |
7,23 |
0,138 |
270 |
BGN 357,70 |
Electric power |
kWh |
BGN 0,14 |
1,00 |
0,14 |
270 |
BGN 362,90 |
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*** ( Average values for: heating area of 270 m3 * 0.04 kW/cubic metre.- specific heating load* 8 hours * 30 days ) |
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