energy storage technology shall not include any property the construction of which does not begin before January 1, 2028. (6) Waste energy recovery property (A) In general The term waste energy recovery property means property that generates electricity solely from heat from buildings or equipment if the primary purpose of such building or equipment is not the generation of electricity. (B) Capacity limitation The term waste energy recovery property shall not include any property which has a capacity in excess of 50 megawatts. (C) No double benefit Any waste energy recovery property (determined without regard to this subparagraph) which is part of a system which is a combined heat and power system property shall not be treated as waste energy recovery property for purposes of this section unless the taxpayer elects to not treat such system as a combined heat and power system property for purposes of this section. (D) Termination The term waste energy recovery property shall not include any property the construction of which does not begin before January 1, 2028. (7) Qualified biogas property (A) In general The term qualified biogas property means property comprising a system which— (i) converts biomass (as defined in section 45K(c)(3)) into a gas which— (I) consists of not less than 52 percent methane, or (II) is concentrated by such system into a gas which consists of not less than 52 percent methane, and (ii) captures such gas for productive use. (B) Inclusion of cleaning and conditioning property The term qualified biogas property includes any property which is part of such system which cleans or conditions such gas. (C) Termination The term qualified biogas property shall not include any property the construction of which does not begin before January 1, 2028. . (5) Denial Of Double Benefit For Qualified Biogas Property Section 45(e) is amended by adding at the end the following new paragraph: (12) Coordination with energy credit for qualified biogas property The term qualified facility shall not include any