In article <telecom25.101.7@telecom-digest.org>, hancock4@bbs.cpcn.com
says:
>>> [TELECOM Digest Editor's Note: A water cooler with a DC motor is
>>> interesting; but did you ever see a _refrigerator_ powered by -gas-
>>> rather than -electricity-?
> Back in the 1960s the city gas works was pushing gas air-conditioning
> for homes. It was a big marketing campaign. If someone got such a
> unit, the gas works would send out cards to the neighbors inviting them
> to come and check it out.
> IIRC, in the early 1960s the city converted from manufactured gas
> (processing coal to create gas) to buying "natural gas". This was
> because pipelines were built between the oil wells and the consuming
> cities and collect gas that was otherwise just thrown away.
> Although cities had gas works for a great many years, gas was
> originally used for lighting. Coal was used for heating. In later
> years gas was used for cooking, hot water, heating, and clothes
> drying, all because it was cheaper than electricity for those
> purposes. In those days, one advantage of living in the city was that
> utility expenses were cheaper -- using gas was cheaper than electricity
> to run the household. Further, utilities charged city residents a
> lower rate since the higher housing density was cheaper to serve.
> In the 1970s this all changed with the energy crisis. I believe the
> domestic gas sources ran out and now gas had to be imported from the
> Middle East along with oil, greatly increasing its cost. Indeed,
> there were shortages and new housing construction had to use
> all-electric instead of gas.
> On railroads, steam was used for air conditioning. There was an
> explanation on the railroad newsgroup of how this worked. Steam had
> the advantage of being freely available as excess from the locomotive
> boiler.
> After the railroads diselized, the diesel locomotives had to contain a
> water boiler for passenger trains to provide steam for a/c and heat.
> This continued into the Amtrak era. Amtrak converted all trains to
> all-electric, eliminating the steam lines which were a problem to
> maintain.
> Someone mentioned Philadelphia's central steam for heating. This was
> once supplied by the Philaadelphia Electric company in a "steam loop"
> that circulated throughout center city. Buildings purchased steam
> instead of maintaining their own boilers. I believe industrial
> processes could even use that steam. The loop still exists although
> it was sold off. The steam generators for the loop may no longer be
> from the electric power plant; Philadelphia Electric has closed down a
> lot of old power plants. One beautiful old building is being
> converted into condos. Anyway, the steam loop has had varying
> fortunes over the years, becoming less popular, but then gaining in
> popularity again. I believe other cities have similar utility
> service.
> Someone mentioned Bell using jet engines for central office power
> backup. I'm kind of surprised at this. The electric companies use
> them for summer supplements. They are very expensive to run, but can
> get up to speed very quickly. I believe the phone companies use more
> conventional diesel engines to power generators. If there is a power
> failure, central office battery has enough capacity to keep things
> going for a while, more than enough time to power up a diesel engine.
> (The jet engine has the advantage of being smaller.)
Speaking of power -- my office is responsible for the central voter
registration system. As such we had to build out our new location to
be as robust as possible when it came to networking and power.
Roughly 30 servers as well as a dozen or so network devices and a
phone switch are connected to an APC Symmetra system that provides one
hour of runtime. That's backed up be a transfer switch and a 125kW
natural gas powered generator. We do quarterly power down tests and
have preventative maintenance contracts on the generator and UPS.
The first test was very interesting. They pulled commercial power at
the panel. The lights went out for ten seconds as those and the AC
aren't hooked up to the UPS. For those ten seconds all cubes in the
I.T. office had lighting and computers. You heard a slight bang at the
ten second mark and then the overhead lights and AC came on. When it
was time to transfer off generator power you just noticed a slight
flicker in the overhead lights. Very smooth system.
T (nospam.kd1s@cox.nospam.net)