section_path: Motive power/Other types
section_name: Other types
paragraph_text: Other types
  
  Various other types of train propulsion have been tried, some more successful than others.
  
  In the mid 1900s, gas turbine locomotives were developed and successfully used, though most were retired due to high fuel costs and poor reliability.
  
  In the 21st century, alternative fuels for locomotives are under development, due to increasing costs for diesel and a desire to reduce greenhouse gas emissions from trains. Examples include hydrail (trains powered by hydrogen fuel cells) and the use of compressed or liquefied natural gas.