Wood pellets (diameter 4 - 10 mm, length 12 - 30 mm) are produced from saw dust, shavings and other wood material, which is being dried and then passed through a hammer mill. While under pressure this material develops a slightly plastified lignine which acts as a natual glue and allows the pellets to take and keep their characteristic form.. For one unit of pellets 7 - 10 units of saw dust and other wood material are needed.
Pellets should be dry (moisure max 10%), should not contain chemical ingredients (glue, varnish etc.), must be stable mechanically. They can be stored in unheated facilities, but must be guarded against moisture. Packed in plastic bags they can remain stored for a long period.
Wood pellets are CO2 neutral and differ in this completely from fossil fuels (coal, heating oil). Burning of pellets does not produce CO2 and therefore is not adding to the greenhouse effect.
Specifications for wood pellets:
- Diameter 4 - 10 mm
- Mosture up to 10%
- Calorific values: From 4100 Kcal/kg, 17100 kJ/kg, from 4,8 MWh/t
- Ash up to 0.5% for high quality pellets, up to 1.5% for industrial pellets
- Density 650 - 750 kg/m3
Advantages for pellet users:
- Pellets are environmentally neutral, do not add to greenhouse effect
- Do not have allergic side effects
- Have very high efficiency coefficient: 85 - 92% of calorific value can be utilised
- Heating process can easily be automatised in specal stoves and furnaces, allowing long term storage
- As pellet producing is a part of the dominant woodworking industry in Latvia, there is no neeed to worry about delivering capacity
- Pellets take up considerably less storage space than firewood
- A neglible amount of disposables: one t of pellets = 5 kg of ash
Options for use of wood pellets:
- Heating of individual homes, enterprises, condominiums
- Energy production in power plants, cogeneration stations
- For liquidation of spills
- In animal farming as waste absorbers
Wood pellets for heating of individual homes
The pellets used for this purpose have ash content up to 0.5%, DIN+ quality. In Latvia they are delivered in 15 - 30 kg bags.
In well-developed markets wood pellets are often delivered unpacked - bulk - in special trucks straight to the end user. This gives the possibility to store the amount needed for the whole heating season close at hand.
Wood pellets for industrial ues
As already stated industrial pellets are designed for energy production at high capacity power stations and cogeneration plants. Ash content up to 1.5%. Calorific value of these pellets is of course the main deciding factor, the size of particles in the material used for pellet productions plays a role here.
Specialists are forecasting a constant growth of the wood pellet market, as many countries are subsidizing and developing a capacity for use of renewable, ecologically clean sources of energy. And that means wood pellets as a priority..