[Stoves] Experiences Using a Hand Crank Generator for Fan Stoves

Sun Feb 24 11:47:45 CST 2008

Just back from examining biomass cooking in northern Vietnam (more honeycomb coal, and charcoal burning - either in no stove or in very bad ones) and chasing Hilltribes and I found new email comments on human powered energy options for fan stoves.  

In primitive villages against the Chinese border I found both ingeniously simple methods for generating power for tedious tasks (like the rice de-husker that used bamboo piped river water to generating a heavy duty unattended reciprocating motion all day long - see this preliminary photo and my comments at http://www.flickr.com/photos/13581309@N03/2285394380/in/set-72157603963966460/)
and more sophisticated but inexpensive ones (an impressive $30 permanent magnet alternator microhydroelectric paddle and generator, for maybe just one family) - where there is a will there is some way.

But the purpose of this is not to bring our attention to long known power sources like these, but to a new one - Mike Lin and Paul Anderson and I were discussing fan needs at ETHOS recently but at the time I didn't realize that Mike is a part of this human power product company:
http://www.potenco.com/products
This yo-yo pull string product is designed for powering cheap laptops and so on in the developing world and seems to have very impressive generating characteristics.  The world is changing around us (cell phones in remote villages, what's next, laptops?) and technology will try to respond.  I'll let Mike comment on the engineering details, but I imagine that the inside of this is similar to my flashlight - permanent magnets, robust/compact electronics for smoothing the output, and some energy storing device (flywheel, supercapacitor, battery etc.).  For me the bottom line for electrical fan systems is still - make the motor as efficient as possible in moving air (also considering fan blade aspects) and everything else will become easier.

Keep searching the world (and the patent database, or just type in "human power electricity" into Google to see all the latest projects) and all we desire will probably be found to already have been thought of.  I am constantly reminded that we tend to do a poor job at predicting the future, or even learning from the past.

Charlie

"Boll, Martin Dr." <boll.bn at t-online.de> wrote: Hi fan fans and all!
 I thought about omitting electrically driven fans and replacing them
only by a mechanically (hand-) driven radial fan, for low-tech reason.
If the fins of the rotor have a little bigger size, the required blow could
even be reached without transmission to change the rotation number/second.
Even that could be made simply by two disks and a rope. 
-Possibly my former low tech-proposal, the MALOT-rotor, could be used in
that sense. -The bow-driven stone-age-version (bi-directional) is not
necessary in that case.
- If there is only (main-)need for forced air in the beginning of the burn
-as by normally natural draft T-LUD is desired (-if I interprete Paul
Anderson's meaning right?) A short time hand-cranking will be done by most.
Who does not want the fire to start quickly and with less smoke?
-And a "coup de chaleur" like some cooks want to have, is easily to manage
as well by this procedure.
Smile and try and let us all know!
Regards

Martin

> Message: 1
> Date: Fri, 22 Feb 2008 19:45:29 +0530
> From: Ruban K 
> Subject: Re: [Stoves] Experiences Using a Hand Crank Generator for Fan
>  Stoves
> To: Discussion of biomass cooking stoves 
> Message-ID: 
> Content-Type: text/plain; charset="iso-8859-1"
> 
> While evaluating this option there are three things to be kept in mind:
> 
> 1. Cost
> 2. Manual work that the consumer is willing to put in
> 3. Technical feasibility.
> 
> I have developed stoves (equivalent of TLUD but slightly different) with a
> hand cranked generator and battery combination. [used for both 6V and 12 V
> fans], so technically the option works in terms that you can get a battery
> charged manually for operating the fans at constant speed for up to 45
> minutes.
> 
> Point 1 and 2 however are unfortunately currently working in the opposite
> direction. Consumers will not be willing to spend more than 5 minutes for
> cranking for each meal, this is only possible with a very high gearing
> ratio for the dynamometer and that gearing ratio means a lot of cost.
> [gearing ratios can be created with a lot of contraptions e.g. charging
> while riding a bicycle etc but these are not consumer friendly.
> 
> For the available dynamometers (e.g. the Philips hand charged radio) the
> time required for charging Vs time that the fan runs at constant speed is
> 1:1.15 which is not good enough for the consumers.
> 
> Coming to other forms of storing energy e.g. mechanical coils etc as in
> toys unfortunately for getting the constant speed operation for a cooking
> duration of over 45 minutes requires a huge contraption which I did make
> but is not useful for consumer scale operations at the right cost (plus
> the stove looks formidable)
> 
> will look forward to inputs from others.
> 
> 
> 
> > From: list at sylva.icuklive.co.uk> To: stoves at listserv.repp.org> Date:
> Sun, 20 Jan 2008 22:40:43 +0000> Subject: Re: [Stoves] Experiences Using a
> Hand Crank Generator for Fan Stoves> > On Sat, 19 Jan 2008 10:11:06 -0800,
> Charlie Sellers wrote:> > >See:
> http://www.bioenergylists.org/en/sellershandcrankpower > > I decided to
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