; (B) generates not fewer than 20 megawatt-hours of electric energy per calendar year; and (C) (i) delivers electric energy to the electric grid; or (ii) in the case of a behind-the-meter generation system— (I) delivers electric energy to the electric grid; or (II) generates electric energy that is consumed onsite for a useful purpose other than for generating electric energy. (10) Generator The term generator means the owner or operator of a generating unit. (11) Greenhouse gas The term greenhouse gas includes each of the following: (A) Carbon dioxide. (B) Methane. (C) Nitrous oxide. (D) Sulfur hexafluoride. (E) Any hydrofluorocarbon. (F) Any perfluorocarbon. (G) Nitrogen trifluoride. (H) Any fully fluorinated linear, branched, or cyclic— (i) alkane; (ii) ether; (iii) tertiary amine; or (iv) aminoether. (I) Any perfluoropolyether. (J) Any hydrofluoropolyether. (K) Any other fluorocarbon, except for a fluorocarbon with a vapor pressure of less than 1 mm of Hg absolute at 25 degrees Celsius. (12) Qualified combined heat and power system The term qualified combined heat and power system means a system that— (A) uses the same energy source for the simultaneous or sequential generation of electric energy and thermal energy; (B) produces at least— (i) 20 percent of the useful energy of the system in the form of electric energy; and (ii) 20 percent of the useful energy of the system in the form of useful thermal energy; (C) to the extent that the system uses biomass, uses only qualified renewable biomass; and (D) operates with an energy efficiency percentage, as determined in accordance with section 48(c)(3)(C)(i) of the Internal Revenue Code of 1986, of greater than 60 percent on a year-round basis. (13) Qualified electricity generation (A) In general The term qualified electricity generation means the number of megawatt-hours of electric energy that a generator generates using a generating unit and— (i) sells directly or indirectly for use by electric consumers for purposes other than resale