F.A.Q – Wood Pellets
Q: What are pellets?
A: Wood pellets are cylindrical pellets made of dry, natural wood waste (sawdust and shavings) with a diameter of 5-6 mm and a length of 10-25 mm. They are compressed under high pressure (without chemical binders) and have an extremely low water content. Wood pellets are supplied in kilograms.
1m³ of pellets weighs 650 kg.
As a comparison:
2.12kg pellets ……………….approx. 1 litre of oil
1 m³ pellets ………………….approx. 320 litres of oil
Q: What is the calorific value of pellets?
A: The calorific value is standardized at 4.9 kWh/kg. Quality is important! For optimal functioning of your pellet heating system use only pellets which comply with Ö-norm or DIN-plus standards.
Q: How does the calorific value of pellets compare with oil and gas?
A: The calorific value of one litre of extra light oil amounts to 10 kWh, as does the calorific value of 1m³ of gas. It is therefore true that: 2kg pellets ~ 1 litre extra light oil ~ 1m³ gas. In terms of price pellets do significantly better than oil and LPG.
Q: How long can pellets be stored?
A: In dry conditions pellets can be stored indefinitely. Attention: if pellets come into contact with water or damp they will expand and be destroyed.
Q: Where do I get the pellets and where are they stored?
A: Wood and therefore wood pellets are an indigenous resource and therefore a regionally available energy source. A small network of manufactures and suppliers can supply a large area. The pellets are delivered by tanker truck, from which they are blown into the pellet store or tank. Unlike oil, pellets do not smell unpleasant! Pellets can be stored in dry storage rooms or in Flexi-Tanks or otherwise in silo bags. The best storage system will depend on the building type, but an especially cost-efficient option is our Flexi-Tank. The Flexi-Tank can be installed in the boiler room, in an adjacent building, or outdoors (if placed outdoors, the Flexi-Tank must be protected against rain and UV-light).
Q: How much energy is consumed in the production and transport of pellets?
A: The energy consumption for the production of pellets is approximately 2.7% of the calorific value of the pellets, compared to LPG at 14.5%, oil at 12%, and natural gas at 10% (Source: Jensch u. Bergmaier, TU Graz University 1997).
Q: How is the quality of pellets identified?
A: There are industry standards which set quality criteria for wood pellets. They include not only the calorific value but also the density, water content, amount of ash, length and diameter, abrasion resistance and the defined capacity (i.e. the number of pellets in a given volume of space). When buying pellets please ensure that you obtain them from certified producers who mark the product as complying with Ö-norm or DIN-plus standards.
Q: Can fuel supply be guaranteed?
A: In Austria, Germany and Switzerland the supply of pellets is guaranteed by an extensive network of distributors. At present the UK distrubution market is increasing month on month, as an Okofen Regional Distributor we will not allow an OkoFen system to be installed in an area where a wood pellet fuel supply is assured, and as OkoFen Regional Distributors we are on hand to assist our customers in sourcing the correct quality fuel. Also the fact that wood is an indigenous resource, and the domestic nature of pellet manufacturing means that pellets are independent of fluctuations in the oil market and foreign energy imports. Already the installed production capacity of wood pellet plants is sized to suit the growing future market, and a deficit in wood supply cannot be expected in the foreseeable future thanks to the millions of tons of residual wood waste produced by the timber processing industry. Wood is a renewable resource and therefore represents and energy source which will continue to be available into the future. Despite rising oil and gas prices, the price of wood pellets has been very stable for years and have even fallen slightly.
Q: Why wood pellets? Does burning wood not generate pollution?
A: It is true that the combustion of wood fuel releases carbon dioxide into the atmosphere. However, the amount of carbon dioxide released is only equal to the amount which was absorbed as the tree grew prior to felling. Unlike fossil fuels which are not being replaced as we burn them, wood fuel is an infinitely renewable resource: provided we replant as many trees as we fell, there will always be a supply of fuel and it will never provide a net increase in carbon dioxide levels.
Of course, a small amount of additional energy is required to harvest, process and transport wood pellets. At present, electricity is used for the production process and petrol or Diesel for transport. However, being an indigenous fuel the distance which wood pellets are transported is far less than the distance oil travels to reach us, and the amount of energy used in the production of wood pellets is significantly less than that used to refine crude oil.
Overall, when burnt efficiently and cleanly as it is in an Ökofen system, woodfuel is as renewable an energy source as you can get.
Q: Can I replace my gas or oil boiler with a wood pellet boiler?
A: Yes – provided you have enough space. An Okofen wood pellet boiler is as automated and easy to use as a gas or oil boiler, and can supply a similar heat output. However, it is important to realise that these are boiler room machines, not kitchen appliances.
Q: Does the automatic wood pellet boiler have to run continuously?
A: No. The boiler is fully automatic, and indeed has complete electronic control over the entire heating system. It will match the heating requirements by modulating (i.e. running at less than full capacity, something which wood pellet boilers do extremely efficiently unlike many wood chip or log boilers), and by cycling (i.e. running to a timetable or shutting down when there is no demand for heating). Of course, being fully automatic, the boiler re-ignites itself electronically whenever heat is required meaning that the building occupant need know nothing about the boiler and its controls.
Q: Can I use my current radiators and plumbing?
A: Yes, provided they are in good condition and were originally designed to be of a suitable size and specification for your building. And if your current radiators are in poor condition or are unsuitably sized for the heat load, they will prove to be inefficient with whatever heating system you use, so are better replaced in any case.
Q: Can I use other fuels in the automatic wood pellet boiler?
A: Not at present. An Okofen automatic wood pellet heating system supplied by Organic Energy is a piece of precision equipment designed to run most efficiently on a high quality supply of dry, dense wood pellets. Research is being carried out by OkoFen’s Research and Development Department and Graz University into different types of pellet fuel, including staw, mithcathus, rape seed, nut husks etc., but to use other types of pellet fuel is not just about the combustion of that material, but also how the pellet fuel is transported, stored etc.
Q: How much will it cost to run? Can I get a grant towards the installation cost?
A: Please see the costs and grants page.