In this chapter:
(1) "Energy source" means any fuel or power source used to power an engine.
(2) "Engine" means a machine for converting an energy source into mechanical force and motion, including a generator or an internal combustion engine.
(3) "Political subdivision" includes a county, municipality, special district, school district, junior college district, or housing authority.
(4) "Retail service station" has the meaning assigned by Section 753.001, Health and Safety Code.