Re: Does POWER_OFF really work ?
- From: johnwallace4@xxxxxxxxx
- Date: Mon, 31 Mar 2008 16:40:31 -0700 (PDT)
On Mar 31, 5:09 pm, VAXman- @SendSpamHere.ORG wrote:
In article <1ea8e2fb-040d-4f8f-ad2f-40a84aabd...@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>, AEF <spamsink2...@xxxxxxxxx> writes:
On Mar 30, 7:46 am, VAXman- @SendSpamHere.ORG wrote:
In article <fsnipf$c5...@xxxxxxxxx>, hel...@xxxxxxxxxxxxxxxxxxxxxxxx (Phillip Helbig---remove CLOTHES to reply) writes:
In article <47ef152b$0$23915$c3e8...@xxxxxxxxxxxxxxxxx>, JF Mezei
<jfmezei.spam...@xxxxxxxxxxxxx> writes:
Figured I would shut down one of my alphas for EARTH-HOUR .
What is EARTH-HOUR?
Just a way to make people concerned about the environment feel good about
themselves and nothing more.
http://www.earthhour.org/
--
VAXman- A Bored Certified VMS Kernel Mode Hacker VAXman(at)TMESIS(dot)COM
"Well my son, life is like a beanstalk, isn't it?"
http://tmesis.com/drat.html
Anything that makes the sky darker, even for only an hour, and/or has
the net result of improving lighthing by increasing efficiency (esp.
by decreasing wasted light that goes up into the sky, helping no one),
and reducing glare (which actually INCREASES nighttime visibility
making a safer and more pleasant nighttime environment), is fine by
me. Bravo!
Seehttp://www.darksky.org/
'Twould be fine with me too but the power-hour wasn't about light pollution,
it was a gesture about conserving energy. Power companies generate electric
based on average demands. I really doubt that they made any fuel consumption
changes based on a minor brief hour dip on the grid.
--
VAXman- A Bored Certified VMS Kernel Mode Hacker VAXman(at)TMESIS(dot)COM
"Well my son, life is like a beanstalk, isn't it?"
http://tmesis.com/drat.html
"Power companies generate electric based on average demands." is a bit
of an oversimplification. They're supposed to install and operate
capacity based on some realistic view of peak demand; some magic
market connection between demand and supply is supposed to make that
happen (hello California).
Once that's done, peak demand is likely significantly greater than
average, so at any given time some capacity sits idle by definition.
It makes sense to have the most expensive-to-run capacity be idle at
any given time, but you have to balance this against the fact that
sometimes you need power which can be switched on (or switched off)
relatively quickly, and that the quickest to respond isn't necessarily
going to be the cheapest to run.
At the "slowest of the slow" end in responsiveness terms is nuclear
power. Nuclear costs are largely impenetrable, it depends on whose
accounting principles you prefer, but the timescales to start up and
for a planned shut down are undeniably long, so nuclear is first on,
last off. Coal has somewhat clearer costs and somewhat quicker
response times, but still far too slow to handle a one-hour "blip".
In the UK and elsewhere, electricity privatisation led to a "dash for
gas" on the mainland where gas was cheap (Northern Ireland was
different, no cheap gas). Large numbers of gas-fired pre-packaged
relatively cheap relatively small relatively fast combined cycle gas
turbine generators (CCGT) were built. In 1989 there were no CCGTs, in
2004 half the UK's fossil-fuel electricity came from CCGTs. CCGTs have
a response time in minutes not hours and could be switched in and out
relatively quickly in a cost effective manner (if you thought that
using scarce natural gas resources for thermal electricity generation
was a long term sensible cost effective use of a limited and valuable
resource, which of course it wasn't, but who could have ever imagined
us Europeans would soon end up dependent on Russia, Libya, Iran and
Iraq [1] for our gas supplies).
At the "fastest of the fast" in this space are the miracles of civil
and electrical engineering known as "pumped storage" systems, such as
Dinorwig in north Wales (www.fhc.co.uk). Dinorwig can go from 0 to
1.8GW output in less than 20 seconds when ready and waiting, or just
over a minute from a no-notice all-stopped condition. And then it can
keep going for a few hours at maximum capacity. Just what you need to
cope with a million or so homes switching on their 3kW kettles all at
the same time, or a lot of people switching lots of things off at the
same time, or to fill the gap for a few minutes/hours till gas and
coal generators catch up after an unplanned shutdown of a nuclear
station. The total UK demand is probably 60GW or so, I forget, so
Dinorwig's 1.8GW is a reasonably sizeable chunk, around half the size
of the UK's largest coal-fired stations (say 4GW).
So, average doesn't really cover it.
One of the more interesting VMS sites in this sector was the national
company which did the remote meter reading for large users. Large
electricity users have their meters read automatically very frequently
(every few minutes) and are charged not just by how many MWh they use,
but also by their "maximum demand" (maximum MW) in an interval. This
national meter reading systems was a VMS cluster, and rightly so,
there was serious money at stake.
Regards
John
[1] http://news.bbc.co.uk/1/hi/uk_politics/3581637.stm
.
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