Renewable Energy : Steam Power

Steam Power and Steam Engines
Steam is also used adjectively and in combination, to denote PRODUCED BY HEAT, or OPERATED BY POWER, or DERIVED FROM STEAM, in distinction from other sources of power.

GreenTrust: Steam Power
Steam Power - Mechanical and electrical power generation from steam.

Thermodynamics of Steam
The steam engine is a heat engine converting heat energy to work. The conversion is performed by a cycle of processes. Heat created externally is transfered to water in a steam generating unit or boiler.

Wikipedia: Steam engine
A steam engine is an external combustion heat engine that makes use of the heat energy that exists in steam, converting it to mechanical work.

Wikipedia: Steam turbine
A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into useful mechanical work.

Green Steam Engine - PESWiki
Designed for practical applications; is said to be extremely efficient, economical and easy to build. Provides an efficient means of converting reciprocating movement into rotary movement, simplifying the piston engine.