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open-ow systems. Energy is extracted, converted, transported, distributed, and used.
Engineers know that the problem with an open-ow system like an irrigation system is
that there is no feedback control. The only way to keep it working is to make sure that the
inow is always large enough that it is capable of meeting the outow. In other words, the
necessary condition for stable and secure operation of the open-ow energy system is suf-
cient spare supply capacity and unconstrained resources.
13.2.2 Feedback Control System Model
For most of the history of energy systems, the open-o ...