I've come around to that conservation of energy stuff ;-)

I understand that your argument involves the energy that enters the
line before it knows anything about the load, the energy that enters in
an initial transient, but unless you can show that nothing happens
during the initial transient to deliver some or all of that initial
energy to the load, your argument has a hole.

You're presupposing that there is some energy that enters the line
during an initial transient that cannot leave until you shut the source
off, so you get the 100J related to the 100W net power flow and 100J
that went into the line before the source knew about the load.. and
then there's another 100J that enters somehow? I guess to set up the
reflected wave?

The argument is circular. The initial transient supplies 200J of
stored energy to the line so there must be 300J in a one second line if
there's 100J in the steady-state fields associated with power flow.
Since there's 300J in the line, the initial transient must have
supplied 200J in stored energy. It's just not working for me.


Dan