Wood chips, pellets or logs?
At Solar Living we understand that deciding which biomass fuel to use can be confusing. As mentioned before, some biomass systems can burn all of the different wood sources but selecting the correct one can sometimes be difficult.
Wood chip is made by chipping or cutting wood. Although there is a market with wood chip, it is not as well establish as the other alternatives so it could be a better option to select pellets or logs if you don’t have a local supply. They tend to be used for medium to large scale semi and fully automated boilers and can often be found on farms and estates. Wood chip of high quality usually has a moisture content of 25-30% so they don’t have a long shelf life as they can degrade quickly.
- Wood chips are generally delivered in bulk using a lorry and require greater storage space than wood pellets
- Wood chip can be easier to obtain in some local areas and as mentioned above you could be able to self-supply the wood
- Biomass boilers using wood chips will require a greater amount of fuel which require more storage space
- As you require more space for storage, these are more suited in commercial properties
Wood pellets are the most popular form of wood biomass fuel due to the availability and convenience of the fuel. Pellets are small and compact and unlike wood chips they have a moisture content of 5-10%. Due to the calorific value of the wood pellets this helps reduce the storage space required. Your wood pellet supplier can supply you with a set size of pellet which makes them perfect for an automated boiler system and because they don’t produce much ash it will keep the maintenance needed at a minimum.
- Wood pellets take up less space than wood chip and logs
- They are easier to control than logs
- They are the easiest to handle of the wood sources
- Produce less ash!
- Pellets do tend to be slightly more expensive than wood chip and logs
- Wood pellets are widely available and can be supplied in bulk or single bags
Wood logs are usually cut into selected sized are usually one meter or so long. Unlike wood pellets, there isn’t a steady supply of wood logs currently so if you were to use wood logs you would want to ensure you can supply your own. Much like the wood chip, you will require more storage space than pellets. One of the negatives of wood logs is that you would need to load the biomass system manually which is very similar to using a wood burning stove, a lot of people want to avoid using wood logs due to this reason.
- Wood log boilers require more manual work than the other two wood fuels
- If you can source the supply locally, wood logs can be cheap – although in most cases you won’t be able to find a good supplier for your needs
- It is not just storage space required; you will need to think of drying and seasoning the logs also!