Efficiency

Tue Aug 30 12:53:39 PDT 2005

12:29 pm Tue 30 Aug 2005

Jim Hickstein wrote:
> Surely a co-lo adds value in the form of a UPS, gen-set, etc.,
> even if these things didn't consume any more power on their own.
> (OK, an automatic transfer switch doesn't dissipate a lot of
> power, but a UPS sure does.)  I would expect to pay a fair bit
> more than the PG&E kilowatt-hour charge.

and Jim Hickstein wrote
> There is also the fact that every time you go through a
> transformer, UPS, battery set, etc. there is some
> effeciceny and loss that you have to build into the price.
> What PG&E charges is what goes into the building.  What
> you get at your server may mean that another 25% or more
> was wasted as heat before it even got to you.

My experience is different.  Well designed transformers are 95-98%
efficient, and battery sets and UPS equipment behind transfer
switches consume miniscule energy once the batteries are fully
charged.  Even the process of charging the batteries takes little
energy.  To recharge a fully discharged 100 ampere-hour automobile
lead-acid batttery, for example, takes less than a quarter's worth
of electricity.

PF