Grain can be an economical and convenient fuel for use in biomass boilers. Pourable grain such as Oats, Wheat and Barley (all which have low nitrogen content) can be used in Guntamatic’s Powerchip and Powercorn biomass boilers.

The calorific values of grain can vary slightly, with Barley giving 4.3-4.4 kWh per kg and Wheat giving 4.5-4.6 kWh per kg. Grain is a slightly denser fuel than miscanthus, so will require less space to store for the same amount of heat.

Grain should not be used with a residual moisture content of more than 13%. Otherwise, energy that would be used to generate heat is used to burn off water, which reduces the boiler’s performance and produces less heat for the same amount of fuel.

The fusion point of grain ash is around 700°C, compared to 1,200°C for wood ash. This gives it a tendency for the ash to bind together, or "clinker", in the firebox.

The moving, self-cleaning step grate in the Guntamatic Powercorn and Powerchip biomass boilers is purpose designed to prevent this.

It is advisable to add approximately 0.3–0.5% by weight of slaked lime to the fuel before use in boilers with ratings up to 50 kW and 0.5–0.8% for boilers with ratings over 50 kW. This increases the calcium content of the fuel, thereby raising the ash fusion point and reducing the amount of clinker that can form in the first place.

The table below shows a comparison between grain and other forms of heating fuel.

A table that lists volume, CO2 emissions and kilowatt hours per kilo of various different biomass fuels
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