Geoscience Reference
In-Depth Information
600
500
400
300
200
100
0
Fig. 1.7 Oil prices on the international market in 2008 euros per barrel 1861
2012. Source my
-
calculations from data in
https://opendata.socrata.com
1.4.6 Energy and Economy
When dealing with energy, we are interested both in the energy input into the
economic system and the share of total energy actually available as mechanical
work and heat. It is well known that energy cannot be created or destroyed, but only
transformed (according to the
rst law of thermodynamics). On the other hand, it is
also known that in any transformation there is a loss of useful energy: a large part of
the energy that is consumed remains unavailable (according to the second law of
thermodynamics). How great this amount is depends on the technical ef
ciency of
the converter (as already seen in Sect.
1.3.4
).
From 1800 on, not only were new fuels introduced on a wide scale, but equally
important was the wider ef
ciency in dif-
ferent energy systems evolved through the following four main stages:
18
ciency in their use. The conversion ef
(%)
1. Subsistence agriculture
5
2. Advanced agriculture
15
3. Emerging industrial
25
4. Advanced industrial
35
As can be seen, modern growth implied not only a rise in the exploited energy,
but also a rise in the ef
ciency of its exploitation. After all, machines are more
ef
cient than animals as converters of energy.
18
From Cook (
1976
, 135).
