Has anybody out there been involved with or encountered the Microgen boiler technology hands-on?
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explains all.
I believe they have been long term testing in hundreds of homes in the UK for the past couple of years.
Looks like BAXI plan to release a product in 2008 and (in principle) I am interested!
Do they work as well as claimed? Are they noisy? Will the technology be reliable?
I reckon the combination of one of these, a heatbank, grid connect "export" electricity meter and some solar tubes would do wonders for the old "Carbon Footprint"
On Sun, 14 Jan 2007 08:38:02 -0000 someone who may be "Vortex" wrote this:-
Reports vary. In New Zealand, where one design comes from, they seem to perform as claimed.
Depends on the design, but I suspect there will always be a little more noise compared to a similar heat only boiler.
With the right maintenance the engineering should be reliable. Depends how good the engineering is and what the design philosophy is.
Should do. As I understand it they are getting the quirks out of the things in the UK environment and organising production before marketing them to all and sundry. Like many things this seems to be taking longer then expected.
Good to see Stirling technology making an entrance. I would like to know more about the electrical control. The FAQ talks of a special meter - so I guess the boiler will just offset the energy you normally use by up to 1Kw.
Is the idea here to try to generate electricity while the heating is running ? I'd like to know in particular how efficient they are at generating electricity, and what proportion of the total input power is dedicated to generating electricity and heat.
Here in N. Ireland a kWh of gas is about 4p, a kWh of electricity is about 12p, so I figure it's going to need to be at least 50% efficient to have a running chance of justifying itself.
They so far do what they claim. Do a Google on this group on "microgen". A Google on CHP might bring things up as well. I have posted quite a bit on this over the years.
Yep it would. Gledhill make a dedicated heat bank for microgeneration.
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to: alternative energies -> portfolio overview.
They claim that "overall" energy consumption will be down 25%. The government is keen on them as a whole housing estate full of them means less electricity infrastructure being run in. Large amounts of housing is being built in Ashford in Kent and Milton Keynes. If they insisted that these new homes had these it would makes difference to these place is infrastructure support. Also when there are 1000s of them together the skills in servicing is available locally.
East Manchester was having trial - Lovel the builders.
On Sun, 14 Jan 2007 10:36:08 GMT someone who may be "John" wrote this:-
Assuming it is connected to the external supply it will work like a similarly connected wind turbine or other local source. When output is possible it will synchronise with the external supply and then put its output into the system. Should the external supply fail it will stop its output, for obvious reasons.
If one is consuming more than the output then it will reduce the amount drawn from the external system, reducing bills. If it is outputting more than one is consuming then it will feed the rest of the system. Whether one gets paid for this depends on one's contractual relationships. One home generation scheme, though I have no idea if they will accept micro CHP output, is
They reduce "overall" energy consumption by about 25%. As electricity is so expensive compared to gas, using it to cope for electricity demands means a greater savings. They is the waste heat from the gas burning to run a Stirling engine that turns a 1.1 kW genny. The Microgen Stirling has no turning genny as we know it, just a free wheeling piston with coils in it.
It is "co-incidence" that peak gas and electricity usage is simultaneous in the real world. So when people use their microgen combi versions for DHW and the CH is on they produce more electrify. They use up to 1.1 kW generated in their homes, if they use less it get exported to the grid. This will reduce power station demand as the power exported may use by next door a few feet away.
Electricity generated in a gas powered station has latent heat losses and line losses, with the best being around 45% efficient by the time you burn it. Generated in the home by gas and used immediately the efficiency is about twice that. If the country had 10 million home CHP units, we would conserve gas supplies. Build to German Passiv Haus specs and the Russians and go and run.
In Scandinavia, they use local CHP stations that pump waste hot water to local houses. Electricity line losses are minimal too being local. The "overall" efficiency is in the 90%s.
The Whispergen is used on many boats as a CHP unit. They have the advantage in that environment of being much quieter than the alternative and of running from the diesel tank or the on-board propane supply. The problem AFAICS is that in all respects they are modest units, providing about 1kW of electrical power and about enough heat to keep a 35ft boat warm and dry. As you indicate although far quieter than a 3-stroke generator, they may be noisy in a domestic environment although they do have a substantial isolation jacket to keep noise down.
Current units appear to me to have a limited use. They can offset the electrical bills for the home, but seem to be only suitable for small or highly insulated homes if used as the only heat source. Mechanical reliability may also be an issue.
The most developed units appear to be those from New Zealand, and at present those are still tiny. If they could be improved to give 3kW of generating capacity I would have one, as it is, they are just too small to consider.
On Sun, 14 Jan 2007 19:12:01 GMT someone who may be "John" wrote this:-
Long answer follows, for those who are interested.
In an AC network all the connected rotating machines rotate together. If they did not then the unbalanced energy, current flows, would destroy the network rapidly. Two AC networks can be connected, a DC link being the most obvious means, in which case rotating machines on the two networks may or may not rotate together, but the machines on each network will rotate together. The links between the UK and France and between the two coasts of the USA are examples of linking two AC networks. This is (a simplified version of) elementary AC theory and should anyone wish to understand it further they should get a book out of a library.
Any rotating machine connected to a large AC network will be synchronised with it, or destroyed in the synchronisation process. At the other end of the electric wiring are a number of power stations which can provide large amounts of energy, current, to force a rotating machine into synchronisation. The machine will either be able to withstand this forced synchronisation or unable to withstand it.
Traditionally when a large alternator was being connected to an AC network the voltage was adjusted to a suitable value and the phase of the output adjusted forwards or backwards until it was close enough to the phase of the network. At this point the circuit was closed and, with luck, the alternator would then run smoothly as part of the network. This was done manually, with dials indicating the appropriate parameters and knobs to adjust them. Getting it wrong produced expensive noises.
The rise of power electronics from the 1970s meant that these processes could be automated, reducing the time taken to synchronise. That is one of the factors behind rapid response hydro-electric stations. For example Foyers can go from standstill to full output in 1 3/4 minutes, while the two decades earlier and far less powerful Sloy took about five minutes. Note that the refurbishment of Sloy a few years ago may have reduced the startup time.
Since the 1970s power electronics have gone from strength to strength. It is now very easy to build a box that will take an input vaveform and turn that into the desired output waveform, one that is synchronised with the external supply, especially at low powers. That is what these micro CHP units have.
There are many variations of such a box. For example modern trams and trains contain such boxes, which take in 750V DC supplies and output three phase AC at variable frequency to drive induction motors. The output is determined by the position of the controller, interpreted via a computer to keep the system within the programmed limits. For example a maximum acceleration limit is one of the parameters.
On Sun, 14 Jan 2007 20:18:10 -0000 someone who may be "Vortex" wrote this:-
It depends on the design. I have not studied any of them in enough detail to say, but I imagine that they all have, or will shortly have if they are an older design, a box to couple the electrical output of the boiler to the external electrical system.
Leaving aside synchronisation there is also the question of disconnecting the boiler from the external supply if that fails. Without such disconnection the boiler would try and feed all loads in the area if the external supply fails, which it will not be able to do. It would also pose a danger to those attempting to repair a fault.
Of course the generator in the boiler may run at 50Hz when it is running at full output, it depends on the design, but this would then be passed through a box to the external system.
Thanks for that David, it's just a pity that it has not a lot to do with the Microgen Stirling engine!
The Microgen unit is a linear free piston stirling engine, so no rotating machines to be seen. Of course electrically it still produces a 50Hz sine wave. There are also absolutely no power electronics whatsoever between the engine and the grid, that's the whole point of a free piston engine: it is resonant at 50Hz and so has no requirement for conditioning electronics. The only electronics are the boiler control system and the G83/1 unit which basically disconnects the engine from the grid if the grid goes outside various parameters.
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