Definitions

# (1)

Aircraft means any contrivance now known or hereafter invented, used, or designed for navigation or flight through the air and designed to carry at least one person.

# (2)

Airline company means any operator who engages in the carriage by aircraft of persons or property as a common carrier for compensation or hire, or the carriage of mail, or any aircraft operator who operates regularly between two or more points and publishes a flight schedule. Airline company shall not include operators whose aircraft are all certified for a gross takeoff weight of twelve thousand five hundred pounds or less and who do not engage in scheduled or mail carriage service. (2.3) Biomass energy facility means a new facility first placed in production on or after January 1, 2010, that uses real and personal property, including leaseholds and easements, to generate and deliver to the interconnection meter any source of electrical or mechanical energy by combusting only biomass or biosolids derived from the treatment of wastewater and that is not primarily designed to supply electricity for consumption on site. (2.4)

# (a)

Except as provided in subsection (2.4)(b) of this section, clean energy resource has the same meaning as set forth in section 40-2-125.5 (2)(b).

# (b)

Clean energy resource, for purposes of property taxation under this section, does not include nuclear energy. (2.5) Repealed. (2.6) Energy storage system means commercially available technology that is capable of retaining electricity, storing the energy for a period of time, and delivering the electricity after storage by chemical, thermal, mechanical, or other means. Energy storage system does not include a solar energy facility, as defined in subsection (3.5) of this section, or a wind energy facility, as defined in subsection (4) of this section. (2.7) Geothermal energy facility means a new facility first placed in production on or after January 1, 2010, that uses real and personal property, including but not limited to leaseholds and easements, to generate and deliver to the interconnection meter any source of electrical or mechanical energy by harnessing the heat energy of groundwater or the ground and that is not primarily designed to supply electricity for consumption on site.

# (3)

# (a)

Public utility means, for property tax years commencing on or after January 1, 1987, every sole proprietorship, firm, limited liability company, partnership, association, company, or corporation, and the trustees or receivers thereof, whether elected or appointed, that does business in this state as a railroad company, airline company, electric company, small or low impact hydroelectric energy facility, geothermal energy facility, biomass energy facility, wind energy facility, solar energy facility, energy storage system, clean energy resource, rural electric company, telephone company, telegraph company, gas company, gas pipeline carrier company, domestic water company selling at retail except nonprofit domestic water companies, pipeline company, coal slurry pipeline, or private car line company.

# (b)

On and after January 1, 2010, for purposes of this article 4, public utility does not include any affiliate or subsidiary of a sole proprietorship, firm, limited liability company, partnership, association, company, or corporation of any type of company described in subsection (3)(a) of this section that is not doing business in the state primarily as a railroad company, airline company, electric company, small or low impact hydroelectric energy facility, geothermal energy facility, biomass energy facility, wind energy facility, solar energy facility, energy storage system, clean energy resource, rural electric company, telephone company, telegraph company, gas company, gas pipeline carrier company, domestic water company selling at retail except nonprofit domestic water companies, pipeline company, coal slurry pipeline, or private car line company. Valuation and taxation of any such affiliate or subsidiary of a public utility as defined in subsection (3)(a) of this section shall be assessed pursuant to article 5 of this title 39. (3.3) (a) Small or low impact hydroelectric energy facility means a new facility first placed in production on or after January 1, 2010, that uses real and personal property, including but not limited to leaseholds and easements, to generate and deliver to the interconnection meter any source of electrical or mechanical energy by harnessing the kinetic energy of water, that is not primarily designed to supply electricity for consumption on site, and that is: (I) A new facility that is a small facility that has a nameplate rating of ten megawatts or less; or (II) A new facility that has a nameplate rating of more than ten megawatts and that:

(A) Is an addition to water infrastructure such as a reservoir, a ditch, or a pipeline that existed before January 1, 2010;

(B) Does not result in any change in the quantity or timing of diversions or releases for purposes of peak power generation;

(C) Includes measures to prevent fish mortality in facilities on on-stream reservoirs and natural waterways; and (D) Does not cause any violation of state water quality standards when operated; or (III) A new facility that has a nameplate rating of more than ten megawatts and that: (A) Is placed into production as part of new water infrastructure such as a reservoir, a ditch, or a pipeline constructed on or after January 1, 2010, and operated for primary beneficial uses of water other than solely for production of electricity; (B) Includes measures to prevent fish mortality in facilities on reservoirs and natural waterways; and (C) Does not cause any violation of state water quality standards when operated. (b) For purposes of this subsection (3.3), new facility includes a combined facility that is a combination of a facility placed in production before January 1, 2010, that uses real and personal property to generate and deliver to the interconnection meter any source of electric or mechanical energy by harnessing the kinetic energy of water and that is not primarily designed to supply energy for consumption on site and an addition or energy efficiency improvement to the facility first placed in production on or after January 1, 2010, if the addition or efficiency improvement increases the electrical or mechanical energy-producing capacity of the combined facility by at least twenty-five percent over the capacity of the facility placed in production before January 1, 2010, alone. (3.5) (a) Solar energy facility means a new facility first placed in production on or after January 1, 2009, that uses real and personal property, including one or more solar energy devices, as defined in section 38-32.5-100.3 (2), leaseholds, and easements, to generate and, except as provided in subsection (3.5)(b) of this section, deliver to the interconnection meter any source of electrical, thermal, or mechanical energy in excess of two megawatts by harnessing the radiant energy of the sun, including any connected device for which the primary purpose is to store energy, and that is not primarily designed to supply electricity for consumption on site. (b) Solar energy facility includes facilities for agrivoltaics, as defined in section 35-1-114 (4)(a), and for floatovoltaics, as defined in section 37-60-115 (12)(c)(III).

# (4)

Wind energy facility means a new facility first placed in production on or after January 1, 2006, that uses property, real and personal, including one or more wind turbines, leaseholds, and easements, to generate and deliver to the interconnection meter any source of electrical or mechanical energy in excess of two megawatts by harnessing the kinetic energy of the wind, including any connected device for which the primary purpose is to store energy. Source: L. 64: R&RE, p. 688, § 1. C.R.S. 1963: § 137-4-1. L. 76: Entire section amended, p. 768, § 1, effective April 26; entire section amended, p. 759, § 16, effective July 1, 1977. L. 81: (2.5) added and (3) amended, p. 1854, §§ 3, 4, effective January 1, 1982; (3) amended, p. 1847, § 1, effective January 1, 1982. L. 82: (2.5) amended, p. 628, § 41, effective April 2. L. 83: (2.5) and (3) amended, p. 1496, § 3, effective April 28. L. 84: (2.5) and (3) amended, p. 989, § 2, effective February 23; (2.5) and (3) amended, p. 997, § 2, effective May 22. L. 90: (3) amended, p. 450, § 27, effective April 18. L. 2000: (3) amended, p. 1738, § 2, effective June 1. L. 2006: (3) amended and (4) added, p. 889, § 1, effective May 9. L. 2008: (4) amended, p. 1319, § 2, effective May 27. L. 2009: (3) amended and (3.5) added, (SB 09-177), ch. 186, p. 812, § 1, effective April 22. L. 2010: (3) amended and (3.3) added, (SB 10-019), ch. 382, p. 1784, § 1, effective June 8; (2.3) added and (3) amended, (SB 10-177), ch. 392, p. 1862, § 3, effective August 11; (2.4) added and (3) amended, (SB 10-174), ch. 189, p. 813, § 8, effective August 11. L. 2021: IP, (2.4), (3), (3.5), and (4) amended and (2.6) and (2.7) added, (SB 21-020), ch. 51, p. 215, § 1, effective September 7. L. 2023: (3.5) amended, (SB 23-092), ch. 218, p. 1132, § 6, effective August 7. L. 2025: (2.4) amended, (HB 25-1040), ch. 45, p. 209, § 4, effective August 6. Editor's note: (1) Subsection (2.5) provided for the repeal of subsection (2.5), effective January 1, 1987. (See L. 84, p. 989.) (2) Amendments to this section by House Bill 76-1235 and House Bill 76-1025 were harmonized. Amendments to subsection (3) by House Bill 81-1309 and Senate Bill 81-025 were harmonized. Amendments to subsections (2.5) and (3) by House Bill 84-1051 and Senate Bill 84-214 were harmonized. Amendments to subsection (3) by Senate Bill 10-019, Senate Bill 10-174, and Senate Bill 10-177 were harmonized. Cross references: For the legislative intent contained in the 2008 act amending subsection (4), see section 9 of chapter 302, Session Laws of Colorado 2008. For the legislative declaration in HB 25-1040, see section 1 of chapter 45, Session Laws of Colorado 2025.