What Is Energy? - The Renaissance of Renewable Energy - page 16

in scale, speed and efficiency. Just as horsepower improved early farmers' ability to work
the land, the harnessing of thermal energy through the steam engine, and later the steam
turbine, allowed a leap forward in manufacturing.

Table 1.2. The power of different prime movers

Early use 1800s 1900s 2000s

Waterwheel < 1 kW 200 kW 400 kW

Windmill < 1 kW 100 kW 400 kW

Water turbine 5 kW 10,000 kW 1,000,000 kW

Steam engine 4 kW 100 kW 5,000 kW

Steam turbine 10 kW 1,000 kW 2,000,000 kW

Gas turbine 100 kW 200,000 kW

Source: Smil ( 2008 ).

The invention of the steam engine set in motion a chain reaction of innovation and
consumption that continues to this day. As people moved from villages to cities to work in
factories,theirhabitsofenergyconsumptionchanged.EuropeanandAmericanpopulations
exploded in the nineteenth centuries, and so too did the pressure on existing energy
resources. Just as we face the challenge of diminishing fossil fuel resources today, societies
of the nineteenth century had to find ways to replace wood and organic oils, up to then the
principal fuels for heating, cooking and light.
ThefirstcountryintheworldtobreakitsrelianceonbiomassfuelwasEngland.Because
of the twin demands of building (ships and houses) and fuel (for industry and domestic
needs), most of the great English forests had already been cut down by the mid-1500s. The
only way to avoid economic collapse was to find an alternative fuel. That alternative was
coal. Coal was not exactly a new discovery; it had been used as early as 200 BCE by the
Chinese and in Europe since Roman times (Smil 2008, Smith 1997 ). However, until the
emergence of the British coal-mining industry, coal was extracted only from outcrops or