PELLET OR PEA COAL?
The question is asked by many homeowners. The advantages and disadvantages of using both fuels considering price, calorific value, ash content, combustion process effects on air quality, and convenience are presented below.
The coal is widely regarded as the most cost-effective heating medium. A tonne of pea coal with the moisture content up to 8% and high calorific value costs approx. 1100,00 PLN. High quality pellets costs approx. 1000,00 PLN. The price of pellet and pea coal is similar (in Poland).
2. Calorific value
The coal features higher calorific value. Average calorific value is 25 MJ/kg for coal and 19 MJ/kg for pellet. It may suggest that the coal is more efficient than pellet, although it is not usually the case. The coal is often used in older boilers, since fully automatic coal boilers are not yet available on the market. Only devices featuring automatic ignition, shut down and air supply can provide combustion parameters optimal for the heat demand. Those innovations were introduced in biomass boilers, including pellet boilers – to allow the device to adapt its combustion process to the ambient temperature. As a result, even with lower calorific value, the economic effect is improved with pellet boilers.
Advanced automatic biomass boiler will reduce the costs of fuel.
3. Ash content
A combustion of one tonne of coal generates 150 kg of ashes, which is a troublesome waste that requires special disposal. The pellet generates almost no waste – one tonne of pellet generates 30 times less ash than coal (approx. 5 kg). The wood ash does not contain any toxic substances and can be used as an eco-fertilizer.
4. Effects on air quality
A very significant disadvantage of the coal boiler is its effect on the quality of air. No other fuel contributes to an environmental deterioration to such a degree. Most available pea coal boilers are Class 3 devices, as per EN 305 -5: 2012, characterized by low combustion efficiency and high toxic substance emission to the atmosphere.
The biomass boilers are also better in terms of ecological safety. Innovative Class 5 boilers guarantee low flue gas emission to the atmosphere.
Krystyna Kubica, many years’ research staff member of the Institute of Chemical Coal Processing and ITC Technical University of Silesia emphasizes that the solid fuels – coal and biomass as our locally available energy sources can be used in individual households in the advanced heating devices utilizing the latest combustion techniques only to reduce the impact on the environment and air quality. The biomass – our largest source of renewable energy is of particular interest, and should be widely used in Poland for municipal and domestic needs, especially in form of pellets or briquettes.
The combustion of biomass and pellet generates carbon dioxide in the same quantity as used by the plants in the photosynthesis process. The biomass combustion does not contribute to the greenhouse effect.
The advanced pellet boiler can be installed in almost any room, e.g. garage or workshop. The room is kept clean without dust inherent in the coal boiler rooms. The pellet boiler room smells like wood, whereas the coal storage areas often have a sulphur-like smell (the coal combustion releases sulphur dioxide causing acid rains).
The new generation pellet boilers ignite and shut down automatically depending on the actual heat demand. With a correct program, the user of a biomass boiler can forget about it until a new fuel batch is required, whereas we are bound up with a pea coal boiler, since its operation is a hard and dirty work that requires constant supervision.
6. Fuel availability
The coal is a fossil fuel with limited availability that must be expertly and reasonably managed. The biomass is a renewable fuel with the resources constantly renewed with the plant growth.
The biomass is not only pellet – the boilers can be fired with oats, wood chips, sunflower husks, nutshells and other eco-fuels.
The costs of both systems are similar, whereas the modern approach allowing for the air quality, comfort and convenience speaks for the more advanced pellet boiler. The biomass heating guarantees clean environment, rooms and air.