Logs

Wood log is the simplest form of biomass, produced from felled trees and branches. As with all forms of biomass, moisture control is of critical importance.

Wood log in particular must be stored until the moisture content is suitable for burning, normally around 20%. This essential, but natural process takes approximately one year and requires the wood logs to be split, shielded from rain, and air circulated around them. Using wet wood will cause poor performance of the boiler and reduce maintenance intervals. Whilst offering the most cost effective and simplest solution, there are several important factors to consider when purchasing a log boiler; time to split and process the wood, suitable space to dry and store the logs, and the daily input required to load and light the boiler during the heating season.

Pellets

Wood pellets are small, typically 6mm in diameter and no more than 15mm long. They are made from processed sawdust and wood chips that have been dried, heated and compressed. When heated and exposed to high pressure, lignin, the binding component in wood, softens and allows the wood product to be
shaped and pressed into a pellet. Their consistent form means wood pellets can be delivered by bag for manual feeding or bulk delivered into a hopper for automatic feeding. Whilst the more expensive of the biomass fuels, wood pellets still offer significant savings against oil, LPG and
electricity, whilst still providing an automated heating solution.

Chip

Wood chips are again completely natural and are made from both waste wood and sustainable virgin timber. Wood chip biomass systems are more suitable for larger applications and for those who can utilize a local source or their own wood supply to make the chip. For high efficiency, wood chip needs to be consistent in size and stored in a covered area that allows air to circulate and naturally dry the chip. Wood chips offer the cheapest form of automated biomass heating.