Biomass heaters consists of a specially designed machine burning a form of wood (chip or pellet) where the heat created by this system is used to heat water, providing a hot water supply to the property. As the source of material (wood) goes through carbon sequestration during its lifecycle; when the wood is burned, the release of that carbon dioxide through burning it is equal if not less to that which the tree has absorbed during its lifecycle. The heaters themselves can work between 90-95% efficiency.

BIOMASS AT CAT 

At CAT, we were shown the plant room which contained the site’s biomass heaters which help in water heating. On site they have both a wood chip and wood pellet biomass heater; the difference between the two is the condition of the wood. The wood chips will be of varying size and taken from the tree directly, which means that it also contains various impurities, air and water, which results in a decrease in efficiency of the boiler. However the wood pellets are processed; the wood is broken down to a fine dust and compressed into pellets. The pellets have the advantage of being able to be produced to the same shape and size, which the heaters can burn more efficiently. Furthermore by compressing the wood into pellets, some impurities, the air and water will be removed from the wood meaning the boiler will be able to perform at near maximum efficiency. Wooden logs can also be used within the system, however similar to wood chip, the logs contain impurities, air and water meaning the efficiency of burning it to the energy created to less than using the wood pellets.

The biomass heaters on site are fed by larger hoppers. A hopper will be filled with the wood chips/pellets and will be directly fed into the biomass heaters. One of the main problems when using a biomass heater is that it has to kept running for long periods of time (cannot be turned on and off due to energy required to heat system up), therefore the hopper has to be continually topped up to keep the boiler going. This will result in many deliveries of the wood if not on site, so the hopper will have to be to be loaded from a lorry directly (unless you want to carry the wood….).

CAT's wood chip biomass heater (Bagnall, 2015)

CAREFUL CALCULATION

Sometimes it is not practical to use biomass, or sometimes can be over-specified. This is the case in CAT with their large scale heat and electrical biomass heater. This biomass heater so big that the site cannot use it; specifically the heat that the heater produces is too great for the site to handle, and there is no other source in which they can output the additional heat into.

APPLICATION TO MY PROJECT

In terms of its efficiency, a biomass heater is seen as one of the best sustainable technologies from CAT we could incorporate into our school project. Nevertheless, the size in of the project, the running time of the heater and finally the continual topping-up of its hopper in mind, I feel that a biomass heater would not be appropriate for the school in terms of size-to-demand and also its running cost. In addition, due to the refilling of the hopper, there would have to be a member of staff down there the majority of the day in charge of refilling and would spend a lot of time in that plant room. 



COMPANIES/SUPPLIERS

Billington Bioenergy - http://www.billingtonbioenergy.co.uk/
Windhager - http://www.windhager.co.uk/



ADDITIONAL LINKS

Biomass Suppliers List - http://biomass-suppliers-list.service.gov.uk/
Ofgen - https://www.ofgem.gov.uk/environmental-programmes/renewables-obligation-ro/information-generators/biomass-sustainability