Strictly engineering aspects of Available Transmission Capacity (ATC)
are analyzed first. Non-linear network theory is used to provide sever
al key conditions under which one could define a notion of Available T
ransmission Capacity (ATC) and specific novel algorithms for its evalu
ation. Next, the fundamental problem which prevents one from developin
g an economically efficient distributed transmission market based on t
he Available Transmission Capacity (ATC) is identified. It is suggeste
d that for an electric power network of an arbitrary topology it is no
t possible to map the computed ATC onto its market value. All findings
are illustrated using examples of small power systems.