Is this a good idea or what?
Has anyone out there got experience of this kind of technology? I can't help feeling there must be a LOT of limitations.
David
There have been stirling engines available for a while, Kuranda marine sell one for use on boats, 12v output, disel fuelled. This seems interesting.
The alternative fuel groups, e.g. Friends of the Earth, have demonstarted a small one that uses sun power. A google on "stirling engine" produces a lot of information.
Lawrence
usenet at lklyne dt co dt uk
There are limitations. It produces 1.1 kW of power. This in itself is fine for houses to run on if all appliances are gas: cooking, tumble dryer, CH, DHW, etc.
It uses a primary small burner at to generate electricity of 1.1 kW via a Stirling engine, which is hermetically sealed like a fridge compressor. The waste heat from the gasses this burner are then run through a normal condensing boiler heat exchanger and an additional secondary modulating burner firing the main heat exchanger gives the required heat for CH and DHW.
There are a few variations under consideration, so there may be a full Combined Heat & Power unit that can run 24/7, rather than just create electricity when running CH and DHW. It is combi sized and fits on the wall with the aim of the electricity people buying power off you when you don't use the full 1.1 kW. There is a normal boiler and combi versions. It is aimed at the replacement boiler market and will just connect into the ring main and the existing pipes, with the 2-way electricity meter installed. The overall "power" consumption is 25% less than a condensing boiler with the retail price about the same as an upmarket condensing boiler.
Having these in all homes in large new housing estates will reduce the need of large electricity infrastructure, and no need for new power stations, as each home will a power station in its own right. Peak demand for electricity coincides with the peak demand for DHW and CH, so the electricity demand peaks will be flattened out. The overall efficiency is very high as it is being produced on site and used in the home or in the local homes. Electricity can be only 30% efficient due to latent heat losses at the power station and transmission line losses.
When there is a power outage the boiler still works. But if the boiler cuts out because of no home demand you will have no lights. They may have an override button, or auto mechanism, to keep the Stirling engine burner firing to give power.
Due out later next year being made in Japan by Rinnai, designed in the UK by British Gas, using the US Sunpower Stirling engine/generator design.
If it can just generate the electricity needed to run your CH heating system it would avoid the problem of having no heat during a power cut.
Colin Bignell
"nightjar" If it can just generate the electricity needed to run your CH heating system
Won't it have to have a safety cutout to prevent it energising dead power lines?
Is this mechanism at the 2-way meter? If there is a power cut I would not like my 1.1kW generator cutting out. That sort of defeats the object.
I'm guessing a bit here and ICBW, but I think you'll find that it's in the microgen.
It _will_ cut out. You'll probably find that the generator is an oversped induction motor, inherently incapable of acting as a stand-alone genny. The _object_ is CHP, not to provide a standby power source. Doing that would increase the cost of the thing significantly, I suspect (frequency control, AVR, etc. needed).
The motor is Stirling engines on the MicroGen is brilliant. It has a free wheeling piston that has no crank. Just a piston moving up and down inside a cylinder. There are coils around the cylinder and in the piston which make up the generator.
I assume there must be some sort of speed control to give the correct voltage and Hz.
If my memory is correct, Microgen say in their literature, I contacted them quite a while back, and it says that it will keep working in a power cut. So I assume backfeed into the grid is stopped at the two-way meter, which is the obvious place to stop it.
A read quite recently somewhere that this will require an additional add-on module, which has not yet been developed.
I would assume this to be something like a UPS to provide it with power to startup and run the controls when there's no demand for heat or 1kW of power, but that's just a guess.
"Sasha Klamp" wrote | I showed these ideas to my boyfriend and he said you were all | doing it the wrong way. All you would have to do he said was | to put some thermal couples in the flue pipe and you would have | the electric you would want. But you would have to put more | thermal couples into the flue pipe for upstairs as the gases | wouldnt produce as much electric when they was cooler. Does | this make sense?
Your boyfriend knows nothing.
Heat rises, so there would need to be fewer thermal couples in for the upstairs, not more. Besides, more electricity is used downstairs in most houses.
Owain
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