colloidal fuel

{{Short description|Emulsion of powdered coal}}

Colloidal fuel is an emulsion of powdered coal in kerosene or fuel oil. It was used in World War I aboard ships as kerosene supplies ran low.{{Cite book|url = https://books.google.com/books?id=KikDAAAAMBAJ|title = Popular Science|last = Corporation|first = Bonnier|date = 1919-07-01|publisher = Bonnier Corporation|language = en}}

Development continued after the war, and in 1932 the Cunard liner Scythia made a round-trip transatlantic voyage partly powered by colloidal fuel containing 40% coal. Advantages over oil included cost and energy density. Colloidal fuel is denser than water, which allows it to be stored under water.{{cite journal |title=Colloidal Fuel |journal=Nature |date=16 July 1932 |volume=130 |issue=3272 |pages=86–86 |doi=10.1038/130086b0|doi-access=free }}