Turbine waterwheels. Gas, steam, and water turbines have a casing around the blades that contains and controls the working fluid. Credit for invention of the steam turbine is given both to Anglo-Irish engineer Sir Charles Parsons (1854–1931) for invention of the reaction turbine, and to Swedish engineer Gustaf de Laval (1845–1913) for invention of the impulse turbine. Modern steam turbines frequently employ both reaction and impulse in the same unit, typically varying the degree of reaction and impulse from the blade root to its periphery. The word "turbine" was coined in 1822 by the French mining engineer Claude Burdin from the
Steamship or turboelectric (the turbines rotate electric generators, which in turn feed electric motors operating the propellers). While steam turbine-driven merchant ships such as the "Algol"-class cargo ships (1972–1973), ALP Pacesetter-class container ships (1973–1974) and very large crude carriers were built until the 1970s, the use of steam for marine propulsion in the commercial market has declined dramatically due to the development of more efficient diesel engines. One notable exception are LNG carriers which use boil-off gas from the cargo tanks as fuel. However, even there the development of dual-fuel engines has pushed steam turbines into a niche market with about