(written from a Production point of view)
The Redondo Power Plant, or AES Redondo Beach is a power plant in Redondo Beach, California.
The power plant stood in for Rigel X as a filming location during the filming of the Star Trek: Enterprise pilot "Broken Bow". The scenes in Redondo Power Plant were filmed on 25 May 2001. Another location standing in for Rigel X was the Hyperion Water Treatment Plant. ("These Are the Voyages..." text commentary, ENT Season 4 DVD)
The power plant was built between 1954 and 1967. The power company AES California currently plans to replace it with a smaller facility, giving room for urban redevelopment. 
- AES Redondo Beach – at AES California