Geoscience Reference
In-Depth Information
calories are not a source of mechanical power for humans and then are not included
in our calculation of past energy consumption. Both fossil fuels used today and
uranium are also energy carriers. They were not until a quite recent epoch, since
they were not utilized in order to produce economic goods and services.
Although the de
nition of energy in physics is much wider than in economics,
the de
nition here proposed is much wider than the ordinary meaning of the term
energy. Many people immediately think of modern sources, when speaking of
energy, and do not include daily food consumption. It is well known that working
animals played a central role in pre-modern agricultural economies, but their feed is
not considered as a main source of energy for humans. The lack of a clear de
-
nition, common to most contributions devoted to the history of energy, prevents
from the possibility of calculating energy consumption in past societies.
1.2.2 Energy and Production
In the long history of technology, main developments consisted in the increasing
knowledge about the possibility of
“
”
energy from the input of natural
resources. The production process and the role of energy can be represented by the
following diagram (Fig.
1.1
).
The diagram can be seen as an illustration of the ordinary production function:
extracting
Y
¼
AF
ð
L
R
K
Þ
:
;
;
Labour (L) and capital (K), the factors of any productive process of useful goods
and services (Y), can be better de
ned, from the viewpoint of energy, as converters
able to extract energy from resources (R) in order to transform materials into
commodities. Y is in fact a function (F) of the converters. The progress of technical
knowledge embodied in A, plays a central role in the production function. In one
input
converters
Labour (
L
)
Resources (
R
)
PRODUCT (
Y
)
Capital (
K
)
Fig. 1.1 Natural resources, converters of energy, product
