Purchasing the correct speci cation fuel is the rst step to energy ef ciency. An inadequately designed or constructed fuel store may allow water ingression, raising the moisture level of the fuel.
All RHI participants must buy ‘dry’ fuels, or allow fuel gathered from their own land to dry out before use, ensuring fuel doesn’t become damp while stored. If fuel is self-sourced, it may be necessary to test its moisture content. Moisture probes are commercially available.
Boiler owners, custodians and operators should check the emissions certi cate for the maximum moisture content allowed for their machine.
So Why 20% Moisture Content?
18–22% is the optimum amount of moisture content required in wood chip to ensure the fuel burns cleanly and ef ciently. It is also the optimum price balance when calculated by the kWhr – which is the true fuel cost measure.
Biomass boilers are generally designed to work to these tolerances to maximise the RHI and to adhere to the clean air act. Those that aren’t will also see improvement in performance levels.
Wood chip with little or no moisture content burn too rapidly. Wood chip with more than the recommended moisture content reduces the power output and causes excessive tarring, ash production and emissions.
Calorific Comparison Example
A 199kW boiler using 200 tonnes of wood chip fuel per year at 45% moisture content is the equivalent of 127 tonnes of Chip Chip 20% moisture content fuel – Saving 73 tonnes/yr.
Remember to check out: www.chipchip.co.uk