Every biomass installation requires a fuel storage system. This can be a designated room in the existing building, but usually it's better to build a new fuel storage system fit for purpose. There are many possible ways to store biomass, but we'd like to focus on just a few most popular and practical solutions. Fuel storage systems are not only biomass “containers”, but also include fuel handling equipment.

The first storage system described is sloping floor silo. This storage system has a square base and a plywood inclined floor with a rotating arm which sweeps the fuel over an auger leading to the boiler. Such storage system can be used for both wood chips and wood pellets. Since the gearbox is underneath the plywood floor, the system must be designed in such a way that there is enough space for maintenance purposes. An example of square silo sloping floor is shown on figure 1.

Figure 1. Square silo sloping floor (www.asgard-biomass.co.uk)

Another popular type of biomass storage system is so-called moving floor. This solution is usually used with larger installations, because it's generally more expensive. As the name suggests, the floor is simply moving the fuel towards the auger positioned at the end of the building. The main advantage of this solution is that lorries can relatively easily unload the material onto the moving floor. This system can be used for both wood chips and wood pellets. An example of moving floor is shown on figure 2.

Figure 2. Moving floor (www.shreddall.com)

The last type of fuel storage described on this website is gravity hopper. This solution can be used only with wood pellets due to the fact that wood chips are light and have a high free-fall angle, therefore it wouldn't be feasible to use gravity hoppers. Wood pellets on the other hand are much more dense and can be used with this fuel storage solution. In this case, gravity delivers wood pellets to the boiler. The main problem with gravity hoppers is due to difficulties with feeding delivered fuel into them. One solution is to use a blowing fan. Figure 3 shows an example of a gravity hopper fuel storage.

Figure 3. Gravity hopper (source: Campbell Palmer Partnership)

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