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Electrical power generation for a given load

grimreaper111

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Oct 29, 2022
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Cornwall UK
I am going to make my own wind turbine, as there is some wind where I live 24/7, to run my 3 PC's and the fridge and freezer. The fridge and freezer are on 24/7 with a combined load of 0.21KW/Hrs. 1 PC will be on around 12 hrs./day at 0.45KW/Hrs. The other 2 PC's will be on on/off during the day at 0.43 KW/Hrs. If all of these were on at the same time the total load would be 1.09 KW/Hrs. for around 12 hrs. a day. Assuming that the wind turbine charges the battery pack to 100% overnight.

  • How many watts would the wind turbine need to generate?
  • What size battery pack should I use, assuming I use lead-acid batteries?
  • I am a mechanical engineer, so this electric bit is new to me. Thank you in advance
 
Welcome to the forum!

You'll probably get the most accurate picture of daily energy usage by picking up a few "Kill-A-Watt" meters and plugging your devices into them for a few days if not a few weeks.

To figure out how much energy you need you it's a pretty simple formula.
Time x Power = Energy
24 x .21 = 5 kWh
12 x .45 = 5.4 kWh
? x .43 = ?

Take a stab at filling out the energy audit resource.
 
I am going to make my own wind turbine, as there is some wind where I live 24/7, to run my 3 PC's and the fridge and freezer. The fridge and freezer are on 24/7 with a combined load of 0.21KW/Hrs. 1 PC will be on around 12 hrs./day at 0.45KW/Hrs. The other 2 PC's will be on on/off during the day at 0.43 KW/Hrs. If all of these were on at the same time the total load would be 1.09 KW/Hrs. for around 12 hrs. a day. Assuming that the wind turbine charges the battery pack to 100% overnight.

  • How many watts would the wind turbine need to generate?
  • What size battery pack should I use, assuming I use lead-acid batteries?
  • I am a mechanical engineer, so this electric bit is new to me. Thank you in advance
You consumption is close to 5kWH per day for the fridge

Plus around 12kwh for the PCs.


Hence 17kwh over 24 hours without any headroom

If you get 50% wind production ( which is very high ) you need 17000 over 12 hours or a turbine capable of 34000 watts. That’s a very big wind unit.

Assuming wind to electrical of then further 50% in efficiency , you’d need 74000W “ capable “turbine.

Again assuming 50 % production your minimum sized battery of 8kwh capability

Of course these are all assumptions

Note that this calculation dues not allow for all simultaneous consumption.
 
Last edited:
Welcome to the forum!

You'll probably get the most accurate picture of daily energy usage by picking up a few "Kill-A-Watt" meters and plugging your devices into them for a few days if not a few weeks.

To figure out how much energy you need you it's a pretty simple formula.
Time x Power = Energy
24 x .21 = 5 kWh
12 x .45 = 5.4 kWh
? x .43 = ?

Take a stab at filling out the energy audit resource.
KWh is not “ power “ it’s a consumption metric.
Hence KWh must be qualified for total time to then compute total watts needed per unit time ( typically 24 hours )

Hence to allow comparison KWh should be normalised to the same unit , typically per day.

So
 
KWh is not “ power “ it’s a consumption metric.
Hence KWh must be qualified for total time to then compute total watts needed per unit time ( typically 24 hours )

Hence to allow comparison KWh should be normalised to the same unit , typically per day.

So
So ... what? I didn't say anything about a kWh being a unit of power.

Actually I think we might be saying the same thing, just differently. lol

Here is how I was trained in engineering school.

Start with the basic formula then do some simple algebra.
Time x Power = Energy 2hrs x 2 kW = 4 kWH
Energy/Time = Power 4kWh/2hrs = 2kW
Energy/Power = Time 4kWh/2kW = 2hrs

A kWh is literally kilowatts per hour which is what we're all used to seeing. Energy per day would be kWh/day.
 
Agree with the above, first do a lot of data logging to determine the true power consumption situation, and don't forget to log wind speeds as well.
Only then can you make some realistic assumptions yourself.

Things would become easier if you have multiple alternative power sources available such as wind, solar, gasoline backup, as well as a battery.
For instance, a gasoline generator might be a cheaper alternative than having a battery large enough to cover several days in a row when wind speeds are unusually low.
 
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