The biomass boilers supplied by Asgard Biomass burn wood chip, wood pellets and logs. Wood chip boilers will burn pellets and energy crops such as miscanthus. Wood pellet boilers will burn pellets manufactured from other energy crops such as miscanthus but not chip. Log boilers will burn logs only.
The boilers will not burn agricultural, industrial or food waste.
Wood chip, wood pellet and log supplies are now readily and reliably available throughout the UK. The rapid expansion in biomass heating has seen the supply chain for wood fuels develop into a professional industry
The wood chip and wood pellet systems supplied by Asgard Biomass are fully automated and require little involvement by the owner other than de-ashing; the ash tray will need to be emptied intermittently, this may be monthly depending on operating time, ash is produced at around 1% of the weight of fuel used. An annual service and flue sweep will be required.
Wood chip systems differ to wood pellet systems in the fuel delivery mechanism. Pellets flow readily and dedicated pellet boilers often use a pneumatic (vacuum) system to transport the pellets from the store to the boiler.
Chip is usually augered from a store, the floor of which has a slowly rotating disc with strap arms (agitator) which stop the chip from bridging in the store and ensures a continuous flow of chip into the auger.
Wood chip has a density of 250 kg/m3 whereas wood pellet is typically about 650 kg/m3. Where space to store and deliver the fuel is constrained pellet may be the preferred fuel.
Logs are a relatively low cost source of fuel, Asgard Biomass log boiler systems have automatic ignition however the boilers do need to be filled manually with logs.
Logs are a good option for smaller properties or as a supplement to other heating sources. The cost of a log system is lower than that of chip or pellet and logs are readily available.
Fuel Supply Contracts
There are a number of companies that offer supply contracts which will guarantee quantities and qualities of wood fuel tailored to meet the customers’ needs. A long term contract provides the opportunity for planning and has the benefit of ensuring a secure supply at the most advantageous price.
Typical supply options include:
- Long term (3-5 years) wood fuel supply contract
- ‘One off’ or emergency delivery
- Fuel can be supplied by the kWh or tonne
Wood pellets are produced out of forestry grown timber and clean waste products from the timber industry. Wood shavings and sawdust pressed together to form pellets. 2.2Kg of wood pellets replaces 1 litre of fuel oil.
Wood chip size varies from 5 to 50mm. The water content of the wood chip should not exceed 30% by volume. About 15m3 of chipped conifer wood is needed to replace 1,000 litres of fuel oil, and about 11m3 if chipped hard wood.
Lower equipment and fuel handling costs make logs attractive for smaller heat requirements. The manual labour involved in a log boiler should be considered thoroughly.
Miscanthus or Elephant Grass has a similar energy density (by mass) to wood chip (3.6 kWh/kg). The ETA Hack boilers are designed to burn miscanthus