FUTURE STEAM POWER
How modern steam trains are ditching coal for cleaner and more efficient engines
WORDS SCOTT DUTFIELD
DID YOU KNOW? The last passenger steam train in Britain ran between Liverpool and Carlisle in 1968
Encapsulated in billowing clouds, steam trains have been trudging around the world’s railway systems for around 200 years. To propel them along their tracks, steam locomotives have used the energy released by combusting fuel, such as coal, to heat a boiler of water.
As the water heats and generates steam, the pressure inside the boiler increases. Attached to the boiler is a piston mechanism that feeds on high-pressure steam, causing it to move back and forth and ultimately driving the adjoining train wheel. The steam then finds its way out of the train through a chimney in billowing white-grey clouds of exhaust.
Using an external combustion engine, traditional steam trains ran the risk of rogue embers igniting other fuel on the train or damaging the tracks below. To mitigate this risk, the first fireless locomotives were introduced to the world in 1882. Like other steam engines, superheated water was the source of their propulsion, but the water was loaded into the locomotives, preheated and pressurised. This meant that the locomotives could only run for as long as the water stayed hot, or until the water ran out.