His family had a long-standing professional interest in
machinery and engineering, and even before moving to Ayrshire, the
Reverend Stirling had been working on ideas for a new type of
engine. He was also aware of the dangers posed by steam-driven
machinery and the frequent explosions that occured during their use
in coal-mines and factories. He wanted to create a safer
alternative.
His engine was unique because it was driven by the heating and
cooling of gas (most commonly just air). As the gas is heated it
expands, and is then cooled and contracts. This expansion and
contraction drives the engine. Crucially, the gas can be heated by
anything from solar power to any type of fuel, and the heating
takes place from outside the engine - this is a significant
difference to the internal combustion engines we are so familiar
with today. Its other characteristics are that it is extremely
energy efficient with very low to zero by-products. Stirling
patented his so-called 'Heat-Economiser' in 1816/17, but the
technology never fully reached its potential and was all but
forgotten. The term 'Stirling Engines' which includes all engines
of this type, was coined around a hundred years later.
Intriguingly, these engines were being developed by Stirling at a
similar time to the other fossil-fuel powered, high-polluting
engines like the steam engine. Perhaps the world would have been a
very different place if Robert Stirling's patent had been the front
running technology.
