; or (II) the subsequent calendar year. (ii) Calendar year 2050 and thereafter Beginning in calendar year 2050, a Federal clean energy credit shall be valid only for the calendar year during which the Federal clean energy credit is issued. (f) Determination of quantity of credits (1) In general Except as otherwise provided in this subsection, the quantity of Federal clean energy credits issued to a generator of clean energy shall be equal to the product obtained by multiplying— (A) the qualified generation of the generator; and (B) the difference between— (i) 1.0; and (ii) the quotient obtained by dividing— (I) the carbon intensity of the generator, as determined in accordance with subsection (g) (expressed in metric tons per megawatt-hour); by (II) the applicable carbon intensity. (2) Qualified combined heat and power systems (A) In general The quantity of Federal clean energy credits issued to a generator that is a qualified combined heat and power system shall be equal to the difference between— (i) the product obtained by multiplying— (I) the number of megawatt-hours of electric energy generated by the qualified combined heat and power system; and (II) the difference between— (aa) 1.0; and (bb) the quotient obtained by dividing— (AA) the carbon intensity of the generator, as determined in accordance with subsection (g) (expressed in metric tons per megawatt-hour); by (BB) the applicable carbon intensity; and (ii) the product obtained by multiplying— (I) the number of megawatt-hours of electric energy generated by the qualified combined heat and power system that are consumed onsite