Income Tax Regulations — (a)
 (i)(A)(II), property otherwise included in Class 10 and property that would be included in Class 17 if that Class were read without reference to its paragraph (a.1), (viii) equipment used by the taxpayer, or by a lessee of the taxpayer, primarily for the purpose of collecting landfill gas or digester gas, including such equipment that consists of piping (including above or below ground piping and the cost of drilling a well, or trenching, for the purpose of installing that piping), fans, compressors, storage tanks, heat exchangers and related equipment used to collect gas, to remove non-combustibles and contaminants from the gas or to store the gas, but not including pollution abatement equipment and property otherwise included in Class 10 or 17, (ix) equipment that (A) is used by the taxpayer, or by a lessee of the taxpayer, for the sole purpose of generating heat energy, not using any fuel other than eligible waste fuel, fossil fuel, producer gas or a combination of those fuels, (B) uses fuel of which no more than 25% of the energy content (expressed as the higher heating value of the fuel) is from fossil fuel, as determined on an annual basis, (C) may include (I) fuel handling equipment used to upgrade the combustible portion of the fuel, (II) control, feedwater and condensate systems, and (III) other ancillary equipment, and (D) does not include (I) equipment used for the purpose of producing heat energy to operate electrical generating equipment, (II) buildings or other structures, (III) heat rejection equipment (such as condensers and cooling water systems), (IV) fuel storage facilities, (V) other fuel handling equipment, (VI) property otherwise included in Class 10 or 17, and (VII) pollution abatement equipment, (x) an expansion engine with one or more turbines, or cylinders, that convert the compression energy in pressurized natural gas into shaft power that generates electricity, including the related electrical generating equipment and ancillary controls, where the expansion engine (A) is part of a system that is installed (I) on a distribution line of a distributor of natural gas, or (II) on a branch distribution line of a taxpayer primarily engaged in the manufacturing or processing of goods for sale or lease if the branch line is used to deliver natural gas directly to the taxpayer’s manufacturing or processing facility, and (B) is used instead of a pressure reducing valve, (xi) equipment all or substantially all of the use of which by the taxpayer, or by a lessee of the taxpayer, is to produce liquid biofuel, including storage, materials handling and ash-handling equipment and equipment used to remove non-combustibles and contaminants from the fuels produced, but not including (A) equipment used to produce spent pulping liquor, (B) equipment used for the collection or transportation of specified waste material or carbon dioxide, (C) equipment used for the transmission or distribution of liquid biofuel, (D) property that would otherwise be included in Class 17, (E) automotive vehicles, (F) buildings or other structures, and (G) pollution abatement equipment, (xii) fixed location fuel cell equipment used by the taxpayer, or by a lessee of the taxpayer, that uses hydrogen generated only from ancillary electrolysis equipment (or, if the fuel cell is reversible, the fuel cell itself) using electricity all or substantially all of which is generated by using kinetic energy of flowing water or wave or tidal energy or by geothermal, photovoltaic, wind energy conversion, or hydro-electric equipment, of the taxpayer or the lessee, and equipment ancillary to the fuel cell equipment other than buildings or other structures, transmission equipment, distribution equipment, auxiliary electrical generating equipment and property otherwise included in Class 10 or 17, (xiii) property that is part of a system that is used by the taxpayer, or by a lessee of the taxpayer, primarily to produce and store biogas, including equipment tha