PART 7Periodic support payments
Periodic support payments for accredited RHI installations in respect of which an application for accreditation is made on or after 24th September 2013
66.—(1) Except where regulation 67, 68 or 70 applies, this regulation applies to an accredited RHI installation for which an application for accreditation is made on or after 24th September 2013.
(2) Subject to regulations 31(2), 69, 71, 72 and 74, periodic support payments in respect of each quarterly period must be calculated in accordance with one of the following formulae, as applicable—
(b)where the accredited RHI installation is generating heat from the combustion of biogas, 
where—
A is the tariff for the installation determined in accordance with regulation 59;
B is the kWhth of heat generated by that plant which is used for eligible purposes, determined in accordance with regulations 23 and 75; and
C is—
the heat in kWhth delivered in the relevant quarterly period to the biogas production plant which produced the biogas which is combusted (other than heat contained in any feedstock used to produce that biogas); or
such proportion (as may be chosen by the participant and agreed by the Authority) of that heat, provided that the proportion is no less than—
where—
x is the heat produced by that biogas which is used for eligible purposes; and
y is the energy content of all the biogas produced by that biogas production plant.