42
3 Energy
Figure 3.2 Change in primary energy demand, 2016–2040 (Mtoe) [In2017b]
using the process variable work [CHR2002, p. 235]. Work W is defined as force F
applied on an object causing it to move a distance s in the direction of the applied
force [MVG2010, p. 27]:
W =
s2
s1
F(s)ds
(3.1)
The SI-unit for W as well as for E is Joule [J]. The usage of this standardized
unit underlines the equivalence of the variables energy and work [Mü+2009, p. 68;
VD2014b, p. 8].
1 J = 1 N ∗ m = 1
kg ∗ m 2
s 2
= 1 W ∗ s
(3.2)
The work of a process related to a period of time is the power P measured in
kilowatt [CHR2002, p. 267]:
P =
W
t
=
[kW h]
[h]
= [kW ]
(3.3)