Editing Steam engine (section)

=== Steam turbines ===
{{Main|Steam turbine}}

The final major evolution of the steam engine design was the use of steam [[turbine]]s starting in the late part of the 19th century. Steam turbines are generally more efficient than reciprocating piston type steam engines (for outputs above several hundred horsepower), have fewer moving parts, and provide rotary power directly instead of through a [[connecting rod]] system or similar means.<ref name=smil>{{Citation|page= 62| title=Creating the Twentieth Century: Technical Innovations of 1867–1914 and Their Lasting Impact|author= Vaclav Smil|isbn= 978-0-19-516874-7 |url=https://books.google.com/books?id=w3Mh7qQRM-IC&q=Transformer+coltman+1988&pg=PA71|access-date=2009-01-03|year=2005|publisher=Oxford University Press}}</ref> Steam turbines virtually replaced reciprocating engines in electricity generating stations early in the 20th century, where their efficiency, higher speed appropriate to generator service, and smooth rotation were advantages. Today most [[electric power]] is provided by steam turbines. In the United States, 90% of the electric power is produced in this way using a variety of heat sources.<ref name="Wiser">{{cite book|title=Energy resources: occurrence, production, conversion, use|last= Wiser |first= Wendell H.|year= 2000|publisher= Birkhäuser|isbn= 978-0-387-98744-6|page= 190|url= https://books.google.com/books?id=UmMx9ixu90kC&dq=steam&pg=PA190}}</ref> Steam turbines were extensively applied for propulsion of large ships throughout most of the 20th century.