RHI payments are made quarterly, in arrears, and require that scheme participants submit regular meter readings related to their heat production and usage via a personal online account. The metering systems are installed at point of generation and point of usage and there are rigorous conditions to be met related to their accuracy.
Getting the right biomass heating system is about much more than just choosing a good quality boiler. High performance biomass boilers are only as good as the fuel they burn. Anything other than virgin wood with no more than 20% moisture content will have a negative impact on the kWh output, maintenance costs and RHI payments.
Get it dry, keep it dry*
Purchasing the correct specification fuel is the first step to energy efficiency. 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. Check the emissions certificate for the maximum moisture content allowed.
RHI compliance tip released by Ofgem June 2015*
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 efficiently.
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.