Cal. Pub. Util. Code § 222
"Gas corporation" includes every corporation or person owning, controlling, operating, or managing any gas plant for compensation within this state, except where gas is made or produced on and distributed by the maker or producer through private property alone solely for his own use or the use of his tenants and not for sale to others.
"Gas corporation" shall not include a corporation or person employing landfill gas technology for the production of gas for its own use or the use of its tenants or for sale to a gas corporation or state or local public agency, except that if the gas produced is of such insufficient quality or heating value that it is unacceptable for introduction into the line, plant, or system of a gas corporation or state or local public agency, the person or corporation employing landfill gas technology may without becoming a gas corporation for purposes of this part sell the gas so produced to not more than four other corporations or persons.
Ca. Pub. Util. Code § 222