🚀 go-pugleaf

In article <1992Jul23.033818.14931@usenet.ins.cwru.edu> bj368@cleveland.Freenet.Edu (Mike E. Romano) writes:

   Actually my original question is poorly worded.
   I am not an engineering major so I do not know the applicable formulas.
   Also my title is misleading and probably creates wrong impression.
   The physics problem is simply this:
   can a suitable wire transfer mechanical or work energy with less loss
   over a long distance (say a quarter mile) than an electric line of
   similar length?
   I am not stating that human labor is superior to machine labor, nor
   that we should return to the pre industrial era.
   -- 
	       Mike Romano     Univ. Calif. Berkeley

It seems to me that part of the question is whether energy conversion
is required at either end.  If so, the losses in the conversion(s)
are likely to exceed the losses in transmission.

In the electrical case, the losses can be made extremely low by using
a very fat cable.  At some point the interest on the capital investment
in the cable exceeds the saving from reducing ohmic loss.  I would suppose
that the usual cable sizes come close to this optimum.  Another
factor is the voltage used.  High voltages transmit energy with low
losses, but the conversion losses are likely to dominate unless the
energy is generated and used at a high voltage.

For very long distances (1,000 miles), it pays to convert the
electricity to very high voltage DC and convert it back again.
The lines taking electricity from the dams in the Pacific Northwest
to Central and Southern California are high voltage DC.

I don't see what the dominant losses would be in the mechanical
transmission of energy for 1/4 mile.  Some kinds of loss are

1. air resistance of the moving cable

2. flexing of the cable

3. bearing losses in the pulleys

I gather the Amish object to using electricity for religious reasons.

In my capacity as an Amish theological expert, I consider it not in
the spirit of the religion to get around its prohibitions by
introducing new-fangled mechancial devices.
--
John McCarthy, Computer Science Department, Stanford, CA 94305
*
He who refuses to do arithmetic is doomed to talk nonsense.