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 Post subject: "Green" computing saves energy?
PostPosted: Wed Mar 12, 2008 3:03 am 
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Maybe not in the winter...... I just spent a few days working on my little LAN. I had all my connected computers turned on at the same time (four). The temperature outside was around 40F. My home thermostat was set for 71F. My gas furnace did not turn on one time between 10am to 5pm. The heat from the computers was enough to warm the house, and keep it above the set temperature.

Had I been using only one low-power, "green" computer all that time, the furnace would have been on/off at regular intervals. When you think about it, the heat from a hot computer was not being wasted, it was substituting for the energy the furnace would have burned.

Of course in the summer the opposite is true. Now to come up with a way to turn the computer heat into a substitute for the air conditioner..... :lol:

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PostPosted: Wed Mar 12, 2008 6:47 am 
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Good thinking Blue.

Prescott furnace anyone? :P

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PostPosted: Wed Mar 12, 2008 6:54 am 
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is it more efficient for the utility to produce electricity at maybe 30-40% thermal efficiency, send it down high-voltage lines (% loss?) then use the computers as resistance heaters, or have the gas piped/trucked to your house and burned in your home furnace which is probably only 10-20% efficient? also bear in mind natural gas burns cleaner than coal, which is probably what your local utility uses.

I'm not saying I have the answer, just laying out the working out for someone who is better at math than me. :)

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PostPosted: Wed Mar 12, 2008 7:08 am 
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your home furnace which is probably only 10-20%


The SEDBUK figures (http://www.sedbuk.com/) suggest somewhat better than this. (e.g. My Vaillant condensing boiler is rated at 91%)

Baring in mind a large proportion of the UK's electricity is generated from gas, electric heating has to be less efficient.

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PostPosted: Wed Mar 12, 2008 9:30 am 
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Ahhh......but most of my electricity comes from the Calaway nuclear plant in northern Missouri. I happen to be part owner of that facility (stocks), so what I use is at least partly returned in dividends.

And the price of natural gas has sky-rocketed around here.....so electricity is now cheaper for heating. Keep those Prescotts fired up..... :lol:

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PostPosted: Wed Mar 12, 2008 12:36 pm 
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Need to be careful of terms here.
Saving money is not the same as saving energy.
Just because at some place and time energy is less expensive in one form than another does not necessarily mean that using the less expensive form is saving energy.

Consider that electricity is mostly generated created from thermal sources. [Main exceptions that come to mind photo-electric, tidal and to some extent wind; just to head off the sticklers - hydroelectric power comes fundamentally from evaportive transport of water, i.e. solar heat.]

That nuclear plant probably heats some fluid, which is then used to spin a turbine to generate electricity. (Likewise gas or coal or oil fired plants.)
So yes, it may be possible to use higher efficiency boilers/etc. to capture more of the energy from the fuel in a power station than in a home, but you also have the losses in conversion to electricity and in transmission.
(Against the losses/energy required to transport fuel.) (i.e. it might be more efficient to eliminate the middle-man and just have a pile of U in the basement, keeping you toasty. ;-) )


jaganath wrote:
send it down high-voltage lines (% loss?) then use the computers as resistance heaters, or have the gas piped/trucked to your house and burned in your home furnace which is probably only 10-20% efficient?


A bit overly pessimistic on furnace efficiency, according to US Dept of Energy estimates:
"Gas
High efficiency central furnace 97.0
Typical central boiler 85.0
Minimum efficiency central furnace 78.0"

http://www.eere.energy.gov/consumer/your_home/space_heating_cooling/index.cfm/mytopic=12330

Electricity distribution loss circa 7.5%
http://en.wikipedia.org/wiki/Electricity_transmission#Bulk_power_transmission


Of course, if you take into account something like heat pumps (where you use the energy not for direct heating, but to effect energy transfer), then your "cooking with gas."

Electricity
Baseboard, resistance 99.0
Central heating, forced air 97.0
Central heating, heat pump 200+
Ground source heat pump 300+

[Don't know if there are heat pumps powered by other than electricity.]


Also, need to account for the energy involved in creating your computing heater. As noted elsewhere, because of the shorter lifecycle and complicated manufacturing processes involved, computers take significant energy to produce. So frequent new parts are out if one wants energy efficiency. (On the other hand, there is so much cool second hand gear out there.)

A case could certainly be made for thermostatically controlled second-hand computers to replace purely resistive electric spot heating. (In a mild climate here, much of the year my (tiny) office is kept adequately warm by body heat and one P3 with a CRT).


I have been wondering about this for a while - when you count the whole energy input (not just the commodity price of what you buy), what are the relative energy efficiencies of the heating sources?


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PostPosted: Wed Mar 12, 2008 2:53 pm 
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I seriously doubt there's a way to calculate any of this......regarding total cost. When you use a computer as a simple electric heater, you also get the added benefit of it's intended use. So how could that be factored into the total cost?

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PostPosted: Thu Mar 13, 2008 12:15 pm 
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Ive been runing a dual opteron heater for 3 years now. It works pretty good.
I find the same symptoms - when my PC, 2 monitors and home stereo are all turned on, it stays noticably warmer in my place.

As for using PC waste heat to heat your house, I view it only as a side benifit. For me, the PC will be running anyway, and as a side effect of that running my heating bill is less.

now if you run a PC for the sole purpose of heating your house... its time to visit goodwill and donate the old hardware and/or have the head examined :)


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PostPosted: Thu Mar 13, 2008 4:51 pm 
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Bluefront wrote:
Ahhh......but most of my electricity comes from the Calaway nuclear plant in northern Missouri. I happen to be part owner of that facility (stocks), so what I use is at least partly returned in dividends.

And the price of natural gas has sky-rocketed around here.....so electricity is now cheaper for heating. Keep those Prescotts fired up..... :lol:


The energy's always greener on the other side.....
Years ago my folks remodeled their house and went with all natural gas appliances to be green/efficient.

problem is they got solar a few years back and now wish they had all electric appliances, so they could run them for free!
:lol:


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 Post subject:
PostPosted: Sun May 11, 2008 10:22 am 
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Sorry, but direct electric heating is really inefficient, because you could always run an air heat pump that can extract extra heat from the cool outside air. It kind of works like a fridge.

Those things can extract like 3W of heating power from the outside air for each W of electricity they use, giving them efficiency of 400% (less when it is really cold outside), while direct electric heating by using a computer can only give you under 100% efficiency at best.

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 Post subject:
PostPosted: Sun May 11, 2008 1:34 pm 
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So, Blue. Now that summer is almost here, what are you going to do in a couple of months when you will need to cool your house instead of heating it and your computers are going to go against your air conditioner?


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PostPosted: Sun May 11, 2008 4:30 pm 
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Well I've come up with a partial solution with my dual-MB Lian Li project. From now on in the summer I intend to use the VIA side of the thing almost exclusively, and particularly in the day-time when things are the hottest. This setup can do most everything I use a computer for..... just more slowly.

Like who needs a 300W computer to listen to MP3s....or watch a DVD, or for surfing? The VIA setup draws 20-25W....hardly anything at all compared to most rigs. I won't say the passive exhaust coming out the top is cooler than the intake air entering at the bottom....but you can't tell the difference by hand.

:D

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