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Comment by Devilboy | Hacker News Reader

The system uses natural gas to generate electricity locally. They say it's up to 85% efficient if you also use the heat it generates to heat your home. Modern large scale natural gas-powered plants seems to be about 60% efficient according to my quick Google searches.

If this thing is cheap enough it could be worthwhile, but only in cold climates where you can use the generated heat.

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Most of the reason that natural gas generators are not more efficient is that utilities aren't willing to pay for that efficiency. Natural gas is more expensive than coal but it can be used in realively inexpensive gas-turbine generators that can be spun up and down quickly to meet rapid swings in demand. Since those plants are only opearted part-time, utilities worry more about capital efficiency than fuel efficiency. Unless these things are cheaper, their added efficiency might not win many existing natural gas generation customers.

A more efficient natural gas generator is fine, but not exactly "green" compared to wind, solar, thermal, hydro, nuclear or other carbon neutral tech. Does this device include carbon capture, or does it just spew CO2?

Yeah, apparently it can (and does) run on methane captured from landfills. That plus efficiency provides the "green" angle.

The Bloom energy cell supposedly works without combustion. So no CO/CO2 etc. But there have to be some byproducts somewhere.

Combustion has nothing to do with it. If it's a natural gas fuel cell then it's reacting mainly CH4 and O2 to produce mostly H2O and CO2, plus electricity and heat. http://www.naturalgas.org/environment/technology.asp#fuelcel...

Does that 60% figure include transmission losses, or is it just thermal efficiency? I'm guessing the latter.

The industry standard for measuring the efficiency of a power generator does not include transmission losses.

However, I have seen people include it in the past as a way of manipulating the numbers. I doubt this is the case with this number. It should be close to 60%

If it doesn't include transmission losses, then how can you meaningfully compare the net efficiency of a colocated device vs. a remote power station?

Transmission losses are probably not included, but for reference this new device is only 35% efficient if you cannot use the heat it generates. If your house (or the weather) is already warm enough, you're not going to come out ahead.

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