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I don't have an engineering background so I apologize in advance if this seems like a silly question.

So I noticed natural gas in my area is a lot cheaper than electricity. So I was asking myself why not get a natural gas generator to produce electricity?

My utility company charges .17 kwh for electricity and .35 per Therm/100 cubic feet for NG. A 10kw generator uses about 200 cubic feet NG per hour. So that's .35x2 = .70 for 10kwh. Or .07 per kwh.

Of coarse there's the initial costs for the generator too.

Am I doing this correct or am I missing something?

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    \$\begingroup\$ I guess you can. But a cheapest NG generator I can find around is about $4K. Would you invest it + the maintenance? I guess it will break before paying out. \$\endgroup\$ – Eugene Sh. Nov 21 '17 at 17:17
  • \$\begingroup\$ I wonder if the increased demand on NG would rise the cost of NG to a point where it's no longer "cheaper than electoeocty" [sic]. \$\endgroup\$ – Bort Nov 21 '17 at 17:19
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    \$\begingroup\$ I would go with solar panels instead... \$\endgroup\$ – Eugene Sh. Nov 21 '17 at 17:20
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    \$\begingroup\$ It may work out cheaper if the generator is running at full power, but if it's very lightly loaded the efficiency will go right down. You also have to consider the noise, deal with the exhaust and find space to house it which will make it impractical for many people. \$\endgroup\$ – Finbarr Nov 21 '17 at 17:27
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    \$\begingroup\$ It's a reasonable off-grid solution, I suppose, anywhere you'd normally be running a gasoline or diesel generator. It seems much cheaper than running a diesel generator, but natural gas isn't as portable as liquid fuels, I suppose. Many people, like some Mennonites, use NG-powered refrigerators already. \$\endgroup\$ – Scott Seidman Nov 21 '17 at 17:32
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Considering the investment for the generator, its maintenance, etc, the only way this would be viable would be to use cogeneration. This means using the waste heat from the generator to heat your home in the winter. In this case, even if the electrical generator efficiency is only 20%, global efficiency will be close to 100% since you'd use the heat.

However this isn't very practical as the generator would only run when heating is required, which may not be at the same moment than you need electricity.

Note that the gas use of the generator you quote is most likely specified at full output power. If you only use a small part of the 10kW power, efficiency will drop a lot. If you don't use any power, the engine will idle and consume gas for nothing.

Also, an internal combustion engine doesn't last that many hours...

If your air conditioning bill hurts, first thing is to add insulation and shade the windows, then you can use solar panels to power your A/C for example. And it doesn't use any gas...

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  • \$\begingroup\$ Cogeneration with heat recovery is standard kit for greenhouses. They turn on during peak hours of the electricity price. \$\endgroup\$ – Jeroen3 Nov 21 '17 at 18:04
  • \$\begingroup\$ What about for commercial use. If you were running some kind of business where you knew you were always going to use the full output power of the generator you would maximize your efficiency \$\endgroup\$ – G-J Nov 21 '17 at 18:05
  • \$\begingroup\$ Combined heat and power is used in industrial situations. The power plant might be a little undersized for the load to allow it to run continuously at rated capacity. The electricity produced offsets imported electricity. The heat produced offsets direct heating or pre-heating of steam, for example. \$\endgroup\$ – Transistor Nov 21 '17 at 18:47
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Some reasons: Noise. Maintenance of generator, e.g. replacing oil. Repair of generator and not having power when it is broken. Most generators use up natural gas even when you don't need more than a little electricity.

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  • \$\begingroup\$ Agreed. We have a Natural Gas generator at my work, however, it's only intended for periodic power outages. Would get expensive and maintenance heavy very quickly as a long term solution. \$\endgroup\$ – Jarrod Christman Nov 21 '17 at 21:53
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Gas generators are the expensive for the use. The energy companies have spare gas turbines ready to be used at any time, this is for immediate start to service in case of sudden rise of power demand. They are intended to work occasionally because of their costs and maintenance, but they do have this property to be launched in operation very fast.

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