Apollo Lunar Module - Hypergolic Reciprocating Engine Power System.

[Graham1973]

One of the more interesting ways to provide power for an extended lunar stay:

This paper describes the hypergolic reciprocator, its development history to date, and the system for which it is the prime mover. Performance testing both on Aerozine-50 fuel/nitrogen tetroxide oxidizer and hydrogen/oxygen is discussed. The contract effort with Marquardt is discussed as well as applications to the LEM for extending the lunar stay time and emergency power. Some treatment is made of the problems associated with utilizing residual propulsion system propellants.

The Hypergolic Reciprocating Engine Electrical Power System and its application to the Lunar Excursion Module.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19700026425.pdf