How Much Energy Is Enough? - The Renaissance of Renewable Energy - page 45

Lifestyle BMR multiple

Collecting water/wood 4.4

Source: FAO 2001 .

While sleeping, an adult male consumes energy at a rate of about 40 watts. At the other
end of the human energy spectrum, an Olympic sprinter achieves a power output of about
2,000 watts, but only in short bursts. An adult male can maintain an energy output of about
80 watts for several hours - enough, for example, to cycle at a leisurely pace. For women,
the equivalent output is about 60 watts (Smil 2008 ) .
Let's compare this to the output of the machines that fill modern lives. A hair dryer, for
example, consumes energy at a rate of more than 1,000 watts, equivalent to thirteen men
riding bicycles connected to electric generators. A wealthy person might still be able to
afford such a hair dryer, but what about powering a washing machine, an air-conditioning
system, or a car? To replace the power output of the twenty solar panels that provide
electricity for my home, I would need sixty grown men riding bicycles on my roof. I would
need almost 200 men to power my car, and to produce the same amount of power as the
world's largest power plant, the Three Gorges Dam in China,I would need more than 250
million tireless cyclists. We take for granted access to quantities of energy unimaginable to
pre-industrial societies (see Tables 3.4 and 3.5 ) . Chances are that readers of this topic enjoy
a far greater energy budget than the kings and emperors of the ancient world.

Table 3.4. The power in watts required to run various devices and the manpower
that would be needed to produce the same amount of power

Device W Working men

Mobile phone 3 0.04

CD player 25 0.31

LCD TV 100 1.3

Computer and monitor 150 2