Posted by kazkotx on August 18, 2008, 3:34 pm
Hey folks. I think we're about to be introduced to peak demand
pricing here in Texas along with a general rate hike. I run a small
personal data center at home since we have fiber here with unlimited
bandwidth. I use a good amount of power. I have been using my watt
meter lately to record and trend devices and have made many power
saving advances because of it, but nonetheless, I use power. We also
have poor line power here so during rainstorms the power can be off
for hours. I need a backup genset because of that, but Id also like
to consider using it to produce my own power at peak rate times from
natural gas.
So I have some questions:
1. How do I go about investigating and calculating the rate of
consumption of natural gas on a genset that I havent bought yet and
then calculate the cost of operation per hour to compare to line
rates?
2. Is there a configuration I can use in place of an automatic
transfer switch so that I can actually feed power back to the grid or
at least reverse my meter if my genset isnt being fully utilized? I
like the idea of staying connected to the grid to handle surge loads
and such and also to accept excess power. How do these things sync
up? I assume this is much the same type of setup one would need if
generating excess solar or wind energy at home which of course I am
interested in as well.
3. What is a good generator and what is a bad generator for this
purpose? I assume I dont want a typical 3600rpm air cooled home
backup system since I plan on running it a lot. I probably want a
larger liquid cooled "brand name" system, probably a surplus unit from
a hospital or such, and I want to oversize it somewhat for my load.
4. When you have a genset that is single phase 240v to hook up to a
typical split phase house to use as a whole house system, is it
assumed that the generator has a center tap coil lead for neutral?
Nobody ever discusses neutral on generators.
5. If I can manage to get some solar and wind systems installed here
in the future, can I leverage them along with my generator to save
money? ie: will those renewable system put out their power for me and
then the genset can make up any remaining load need while conserving
fuel as much as possible. Or do gensets typically run full throttle
and suck the same amount of gas regardless of the load.
Hopefully I made my desires clear. Minimally it will be a genset with
a transfer switch to cover my line outages. Preferred would be a
genset that can work with line power somehow and also allow the
addition of future power generation devices with minimal effort.
Posted by Ron Rosenfeld on August 18, 2008, 4:32 pm
On Mon, 18 Aug 2008 12:34:17 -0700 (PDT), kazkotx@gmail.com wrote:
>Hey folks. I think we're about to be introduced to peak demand
>pricing here in Texas along with a general rate hike. I run a small
>personal data center at home since we have fiber here with unlimited
>bandwidth. I use a good amount of power. I have been using my watt
>meter lately to record and trend devices and have made many power
>saving advances because of it, but nonetheless, I use power. We also
>have poor line power here so during rainstorms the power can be off
>for hours. I need a backup genset because of that, but Id also like
>to consider using it to produce my own power at peak rate times from
>natural gas.
>So I have some questions:
>1. How do I go about investigating and calculating the rate of
>consumption of natural gas on a genset that I havent bought yet and
>then calculate the cost of operation per hour to compare to line
>rates?
Good generators will have specifications from which this can be calculated.
>2. Is there a configuration I can use in place of an automatic
>transfer switch so that I can actually feed power back to the grid or
>at least reverse my meter if my genset isnt being fully utilized? I
>like the idea of staying connected to the grid to handle surge loads
>and such and also to accept excess power. How do these things sync
>up? I assume this is much the same type of setup one would need if
>generating excess solar or wind energy at home which of course I am
>interested in as well.
Power companies are only required to do this with RE sources.
>3. What is a good generator and what is a bad generator for this
>purpose? I assume I dont want a typical 3600rpm air cooled home
>backup system since I plan on running it a lot. I probably want a
>larger liquid cooled "brand name" system, probably a surplus unit from
>a hospital or such, and I want to oversize it somewhat for my load.
1800 rpm / liquid cooled. Consider diesel if you are going to be running
more than a few hundred hours per year. Look for something that is rated
to provide "Prime Power".
>4. When you have a genset that is single phase 240v to hook up to a
>typical split phase house to use as a whole house system, is it
>assumed that the generator has a center tap coil lead for neutral?
>Nobody ever discusses neutral on generators.
There are some issues with making sure it is properly bonded to your house
ground, but any licensed electrician should know how to hook this up, and
the generator people should check things out and do the intial startup.
>5. If I can manage to get some solar and wind systems installed here
>in the future, can I leverage them along with my generator to save
>money? ie: will those renewable system put out their power for me and
>then the genset can make up any remaining load need while conserving
>fuel as much as possible. Or do gensets typically run full throttle
>and suck the same amount of gas regardless of the load.
>Hopefully I made my desires clear. Minimally it will be a genset with
>a transfer switch to cover my line outages. Preferred would be a
>genset that can work with line power somehow and also allow the
>addition of future power generation devices with minimal effort.
It's hard to tell what would be best for you without knowing more.
If you can tolerate the short power outage between grid failure and
generator start, then a transfer switch and generator would be the way to
start.
If you require good power 24/7/365, and are serious about adding PV or wind
in the future, then consider an inverter and a battery bank at least
sufficient to tide you over until the generator starts. The inverter can
manage, automatically, the switch over to the generator; starting and
exercising the generator, charging the batteries (from either the grid or
generator), feeding the grid if it is legal in your area. When you add
solar and wind sources, you may want to change your battery bank to
something larger, but that would be down the line. The solar and wind
sources would be used to charge the battery bank, and would have
appropriate controllers on those systems.
--ron
Posted by Vaughn Simon on August 18, 2008, 6:00 pm
> 1. How do I go about investigating and calculating the rate of
> consumption of natural gas on a genset that I havent bought yet and
> then calculate the cost of operation per hour to compare to line
> rates?
All reputable generator manufacturers give fuel consumption specifications
for their models at various loadings.
.
> 3. ...and I want to oversize it somewhat for my load.
This is a basic human tendancy. "I f big is good, then bigger must be
better". Don't fall for it. Fuel is expensive, and generators are most
efficint when loaded over 50% or so. Figure out your needs and "right size"
your generator.
> 5. ...do gensets typically run full throttle
> and suck the same amount of gas regardless of the load.
NO! Most generators run at the same SPEED regardless of load, but throttle
position and fuel consumption depends on the load.
> Hopefully I made my desires clear.
It sounds like you have a genuine need for a standby generator system, but it
is unlikely that it will ever save you money. When you figure out how much it
costs you to generate your own power, you will conclude that grid power is a
bargain regardless of your rate structure.
--
Vaughn
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Nothing personal, but if you are posting through Google Groups I may not receive
your message. Google refuses to control the flood of spam messages originating
in their system, so on any given day I may or may not have Google blocked. Try
a real NNTP server & news reader program and you will never go back. All you
need is access to an NNTP server (AKA "news server") and a news reader program.
You probably already have a news reader program in your computer (Hint: Outlook
Express). Assuming that your Usenet needs are modest, use
http://news.aioe.org/ for free and/or http://www.teranews.com/ for a one-time
$3.95 setup fee.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Will poofread for food.
Posted by kazkotx on August 19, 2008, 6:01 pm
So do gensets come with a center tap in order to feed a split phase
house? ie: how does my 240v generator power my 240v HVAC, stove and
also my 120V things? Can you just wire it 240 + neutral like the house
is fed or do you have to creatively feed 240 to the devices needing it
and then the 120V to the devices needing it through the magic genset
breaker box?
Seems much easier to wire using a simple transfer switch to feed the
entire house with power and utilize the existing breaker panel if you
wish to remove loads first. What am I missing here?
Posted by Don T on August 19, 2008, 6:44 pm
> So do gensets come with a center tap in order to feed a split phase
> house? ie: how does my 240v generator power my 240v HVAC, stove and
> also my 120V things? Can you just wire it 240 + neutral like the house
> is fed or do you have to creatively feed 240 to the devices needing it
> and then the 120V to the devices needing it through the magic genset
> breaker box?
> Seems much easier to wire using a simple transfer switch to feed the
> entire house with power and utilize the existing breaker panel if you
> wish to remove loads first. What am I missing here?
A typical air-cooled portable generator will have a 4-wire 240 outlet.
120-120-neutral-ground with the neutral either bonded or floating. A method
of determining which way it is wired is here:
http://members.rennlist.org/warren/gt5000c.html
If you are specifically talking about a dedicated home "Standby" genset
then look in the bleeding manual.
--
Don Thompson
Stolen from Dan: "Just thinking, besides, I watched 2 dogs mating once,
and that makes me an expert. "
There is nothing more frightening than active ignorance.
~Goethe
It is a worthy thing to fight for one's freedom;
it is another sight finer to fight for another man's.
~Mark Twain
>
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>pricing here in Texas along with a general rate hike. I run a small
>personal data center at home since we have fiber here with unlimited
>bandwidth. I use a good amount of power. I have been using my watt
>meter lately to record and trend devices and have made many power
>saving advances because of it, but nonetheless, I use power. We also
>have poor line power here so during rainstorms the power can be off
>for hours. I need a backup genset because of that, but Id also like
>to consider using it to produce my own power at peak rate times from
>natural gas.
>So I have some questions:
>1. How do I go about investigating and calculating the rate of
>consumption of natural gas on a genset that I havent bought yet and
>then calculate the cost of operation per hour to compare to line
>rates?