Sounds to a whole lot more viable and useful than burning wood.

Hi Luffy,

I found similar stuff on the web, but only generating minute amounts of power.

The ratings given by Toshiba seem much more useful. The stove probably runs at a much lower temp than 800 c, but getting 1 watt /cm2 looks quite useful. 10x10cm plate =100watts!?.

As usual, we're 5 years too early as it looks to be at experimental stage, but let's keep our fingers well and truly crossed!

I'd be interested to see the sums!

I think that the scale required (and the tinkering/fuel feeding needed with a low efficiency system) to get sensible amounts of energy is going to make it very hard to do.

The best existing thing, to provide a benchmark, I have seen is those big Canadian Stirling fans (http://www.gyroscope.com/d.asp?product=THERMALENGINE) as mentioned by somone earlier. This is a great product in that you just put in on the stove and walk away, similar to the ecofan, with maintenance amounting to a bit of oiling from time to time. The challenge is to produce a steam version to generate more energy than this at a similar price per KW (or fraction thereof) with a similar fit and forget approach.

At the end of the day much cheaper and simpler to get an old Lister engine and run it on chip shop fat (if you have the space) as ted said.

I love steam but getting it to be efficient at small scales is probably not possible - could be great fun & sort of 'practical' though if you went for the "hamster wheel mobile phone charger" type of approach.

S.

There was a (profoundly eccentric) bloke in Kelso a while back offering a co-gen module for his apparently super-efficient open fires. I could never find out exactly how it was supposed to work and as he's now dead I doubt I ever will. Dean Warwick, company was (/is?) Ampliflare, I think. Whackiest brochures I ever saw.

Paul

these are made in NZ by whisper gen, unfortunately for the UK one of our main power suppliers bought the rights (power gen I think) apparently if you go to ireland you can buy them !
tom

dickster,
they certainly could, prior to steam engines being build they were 'the' motive force, whole factories were run. with modern equipment/materials/technologies a small Stirling generator could be easily produced. Philips electrical did in the fiftys/sixtys it used any liquid fuel, but any heat source would do in a fixed installation. see http://www.starspin.com/stirlings/ph1p.html
I built one in the seventy's that used solid meths blocks as fuel it would run well for 1/2 hour, after that the whole unit became too hot to have enough heat differential to run, the hot end could have been placed into the stove and the cold end(cooler the better) could have been jacketed and maybe even preheat the incoming house hot water supply. You would have a constant clankety clank noise and regular oiling/maintenance to contend with, whereas the whispergen is a hermetically sealed magnetic piston oscillating directly through a coil, maintenance free.
tom

Sorry skywalker, I was refering to hot air engines in general at the start of my comment.
I believe you'll find that hot air engines are more thermally efficent than steam engines and you can get usefull power from quite a small unit. take a look...
http://www.keveney.com/Stirling.html
http://www.enatec.com/English/enetec.html
http://www.sunpower.com/
http://www.stirlingengines.org.uk/
http://www.stirlingengine.com/ecommerce/product.tcl?usca_p=t&product_id=84
tom

the enatec web site above will supply, look at the technology page, I would be interested in the wood burner conversion/development.
tom

tuna,
Can you get a 1kw stove ? or are we talking camping stoves, our wood burner is rated at 12kw. Any idea how much a whispergen costs ? I can't seam to find out. They do replace your boiler as well as generating electric for the price

tom

Fron an article in Home building and rennovating the payback on a whispergen is quite good. Around 5 years compared to installed a new gas condensing boiler. This assumes you were selling electricity at half the rate you are buying it. Sticking on ein just becuase you can wouldn't be a good idea. They are only suited to 3 bed older houses or better insualted new houses as the heating part of the boiler isn't that highly rated.

One thing to consider with any mods to a wood burner is that lowering the combustion temperature by adding back boilers or possibly a stiring engine would reduce the efficiency of the burn. This is something I've found out from living in a smoke control area. You can get all these new highly efficient wood burners but not many a suitable for smoke control areas. The ones that are, can't have the back boiler option as it stops the clean burn. So it's better put next to a large soap stone or masonry wall to absorb the heat on a max burn, to then be re-radiated out slowly and get a 75% efficiency on the initial burn (wood-> useable heat). If you start adding boilers and the like that initial 75% will drop (to what I don't know) and you'll create more carcinogenic and particualte pollutants.

Maybe you should put your energy [;-)] into getting that stream making a continous trickle of electric , and have a pumped storage system.

Efficiency is great, however there will always be a more efficient way of doing everything. Are there any less efficient ways of doing this? Is there an enclosed waterwheel generator that could be hooked up to a garden hose? Something like that I would think could be used in an application such as a wood burning stove an old car radiator and a one way pressure check valve. You might not get 400W of power from it but I would think any charge you could put toward the batteries would benefit.

Been Looking round Navitron more than usual as I am so close to getting solar I can almost touch it!

Found these threads:

http://c-zero.co.uk/forum/index.php/board,23.0.html

More grist!

S.

Hi Renewable John.

Why can't we scale down to much smaller, as in my original question?, (Apologies to previous commentators). I just read that 1Kg of log = approx 4KWh, 1kg of log = 1KWh of leccy using your 25% rule of thumb. If I'm considering spending oodles on alternative generating methods and only using 4.5 Kwh per day, could a stove with boiler do the job?

Happy Monday!

Understood, thanks, but to a point which renders the idea a "no go"?

Right, so you meant:

Minimum size 60kw fire (heat energy in) converts to 6kw electric (10%), 24kw usable/tranferable heat (40%), rest losses due to conversion and waste heat.

Sounds better!

So if 1kg log = 1kwh it will = 0.1kwh electricity (if you are lucky), I would be inclined to cut this in half due to scale losses (given our target production id 4.5 kwh). So we are looking at a very rough minimum (calculated by means which has probably got some of the more physically minded pulling their hair out) of about 100kg of very dry wood and a lot of heat looking for something to do.

You can see why CHP only starts to work at a community level.

Dickster have you thought about a trail run?

Buy the biggest ready made steam engine the research and development committee will allow. There are the stuarts we talked about earlier or ANTON ( or many more). Then get a boiler made up to suit

You could probably get a cross tube boiler made that sat in the flue outlet on your fire. Same bore as your flue with a number of 10mm tubes criss crossing the flue space. A good model boiler maker should be able to help. This one is very well thought off:

http://www.cheddarvalleysteam.co.uk/

This chap used to make the boilers for the puffin (which Stuart now sell) when it was made by cheddar valley steam). You could of course just get one of them and base your research on it:

http://www.stuartmodels.com/inprod_det.cfm/section/readytorun/mod_id/97

There are others in the ads in the back of model engineering etc.

You will need to manualy or automatically feed it with water for the time your fire is running (boiler feed pumps can be had on ebay or many model steam people do them) as you must not let it run dry.

All you then need to do is hook it up to a model boat motor (in reverse) to see how much power you get.

If you call the model engine maker of your choice they should be able to tell you what the power output of the model is & how much gas it uses for a run.

S.