[Digestion] the perpetual motion machine

[Warren Weisman]

Looks good to me. It's not a perpetual motion machine, as efficiency is lost in combustion in the generator, conversion of fuel into mechanical energy and heat, conversion of mechanical energy into electricity. However, it is sustainable and millions of people are already doing it around the world. A perpetual motion machine---which I've got one I'll sell you for $199 US---would allow you to watch TV without perspiration. No-one is suggesting that. 

Possibly some beans could make up for the N lost through volatilization, run-off and leeching? Personally, I'd situate my digester where human waste could be used and it could be a part of water treatment process, but obviously that's not always practical. 

Warren Weisman
USA

--- On Sun, 11/21/10, Hoysall Chanakya <chanakya at astra.iisc.ernet.in> wrote:

> From: Hoysall Chanakya <chanakya at astra.iisc.ernet.in>
> Subject: [Digestion] the perpetual motion machine
> To: "For Discussion of Anaerobic Digestion" <digestion at lists.bioenergylists.org>
> Date: Sunday, November 21, 2010, 3:33 AM
> The grand perpetual motion machine
> symptoms,
> Not really - what you need to see is that there will be
> losses and
> leakages from this "grand system" and to keep it running
> you need to
> reduce your energy losses to minimum and have practically
> no N losses.  At
> some scale your dream will come true.  Then of course
> comes the cost -->
> where you need to decide if it is worth it afterall.
> best wishes
> chanakya
> 
> 
> > Okay... since we're on a roll here, tell me if you
> think a scenario
> > similar to the following sounds TOO FAR OUT:
> >
> > animal manure goes into an in-ground plug/flow
> digester;
> > spent digestate goes to both sediment pond and aerobic
> compost pile;
> > sediment pond produces duckweed and nutrient for
> hydroponic grow beds;
> > duckweed is harvested and dried for animal feed;
> > methane produced runs an engine;
> > engine coolant keeps digester warm (radiator coils
> wrap around digester);
> > engine runs generator to produce electricity;
> > electricity lights and runs pumps for hydro
> > .... what have I forgotten?
> >
> >
> >
> >
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> -- 
> Dr. Hoysall Chanakya
> Centre for Sustainable Technologies
> (Assoc. Faculty at Centre for Infrastructure, Sustainable
> Transport and
> Urban Planning (CiSTUP) and Centre for Contemporary
> Studies)
> Indian Institute of Science, Bangalore 560 012
> ph 91-80-2293 3046; fax-91 80 2360 0683
> 
> 
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> and the Biogas Wiki http://biogas.wikispaces.com/
> 
>