Small scale CHP for domestic/light commercial

Small scale CHP has finally arrived for the domestic/small commercial installation.
whispergen, a NZ company have developed a unit which would suit such a purpose and which uses a modified stirling engine to produce electrical energy from natural gas, the excess being sold back via the grid and the "waste" heat being used to produce heating and hot water.
see http://www.whispergen.com
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I'm all for green things and energy efficiency but this doesn't seem quite right.
The site says it _must_ be connected to the grid to operate. I take that to mean that in a powercut, or off-grid property, it's useless.
Also with a maximum electrical output of 1.2kW while producing 8kW of heat (not enough for a pumped shower) it's not enough for a non-idling house's electricals while this time of year who wants 8kW of heat ? I don't use a continuous 8kW in the winter.
Powergen's website says it costs 3000 and "However, even if a replacement boiler costs 500 less, installing a WhisperGen will pay for itself within 4 years." On another page Powergen pay you 30 for the electricity you produce and don't use, 1000kWh. So Powergen are only paying you 3p/kWh which is measly if it's saving them transmission losses.
Jon
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Indeed. I believe they were researching some sort of system to allow standalone operation. Note that this is not unusual for generating plant. Many full scale power stations can't operate without a grid to lock on to!

Basically, it produces electricity when you have a call for heat. 8kW would be a reasonable supply to a small house in winter, although in particularly cold weather with lots of baths, it might need some help.
In summer, where there is less call for heat, less electricity is produced and you will need to buy more off the electricity supplier. Think of it as a source of cheap electricity whenever your boiler happens to be firing.
Christian.
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Jonathan Schneider wrote:

And youre not alone there. So IRL the mean power output is much lower. It would produce that 1.2kW more of the time if used as part of a larger system, eg in flats.

fair price. But with so little output, how its ever going to pay its extra 2k cost I dont know. I dont know what servicing will add to that..
NT
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On Thu, 13 Jul 2006 09:57:50 GMT, Jonathan Schneider

8kW seems a bit low for winter. I'd need two ;-)
Mark
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wrote:

It is designed for modern homes with modern insulation values. Having a housing estate full of these will mean less infrastructure into the estate. Also the time of peak electricity demand and gas demand conincide. So homes producing 1.1kW that may use most of cuts down on the grid. 1.1Kw is more than enough for average use. What you don't use turns your meter back for someone else to use. They are meant to work with a thermal store using a thermal store you can cut back the boiler size to average usage not peak as we do on a direct to a system boiler. 8KW will be fine using a thermal store.
Electricity is about 4 time the price of gas. If that can be drastically cut back using gas then you are on a winner. All the figures of savings do add up. The government approves of them too, after much research.
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On Thu, 13 Jul 2006 10:10:40 +0100 someone who may be tarquinlinbin

Hardly news. They were being discussed last year with regard to UK installation.
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David Hansen, Edinburgh
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On Thu, 13 Jul 2006 10:10:40 +0100, tarquinlinbin

You're about 5 years late mate, they were on (limited) trial in the UK back in 2000/2001.
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wrote:

That is right Lord Hall, remember I told you.
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tarquinlinbin wrote:

Bit of a toy CHP - real ones use gas turbines to generate electricity, so the heat is more of a by-product of generation, rather than the other way about. Now if someone came up with a miniature gas turbine.....
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Phil wrote:

Plenty around
This is one of the most impressive I have seen fly, and it comes geared to net around 7K RPM output - 6KW of shaft power..probably about 6K of heat too..
http://www.wrenturbines.co.uk/product.php?pid=3
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Now this is just silly...
http://www.wrenturbines.co.uk/gallery/photos/64.jpg
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On 14 Jul,

Don't let Austin see that!
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Plenty of them about, modellers use them for aeroplanes. They're not terribly efficient though but do produce the most amazing models.
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Skipweasel
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wrote:

The chief attribute of the Stirling in this context is that it's quiet and using a gas burner is very clean. The hope is it will be long lived.
Honda "launched" a similar device based on one of its little industrial engines which had a higher conversion to electricity, this because the internal combustion is thermodynamically better at converting heat to motion.
There is a CHP micro turbine but it's a lot bigger, search on Capstone, I know little about it but I do know that to get high efficiency you need high pressure ratio and that's expensive.
Our little lucas gas turbine is noisy and at best 11% conversion efficiency and I don't know how many operating hours you can risk spinning something at 60k rpm and 1100C.
AJH
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http://www.microgen.com/main2.swf
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Wondered when someone would come up with Microgen, I left two weeks ago!
Steve
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On Fri, 14 Jul 2006 19:14:27 +0100, Stephen Barnes wrote

Not selling very well then?
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Matt, seeing that it is not on sale, I would think sales are low.
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Fill us in then.
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