[Stoves] Stoves Digest, Vol 19, Issue 2

[Steve Roggenkamp]

You should also take into account the amount of infrastructure required 
to supply heat to the pot.

A pot on an electrical stove:  central electrical power generator, 
kilometers of electrical wire, household wiring including circuit 
breakers, manufactured stove to support the pot, mining operations to 
supply the coal/nuclear processing facilities/etc. to supply heat to the 
electrical power generator, petroleum fuel to transport the fuel, and so on.

Three stone fire:  three stones and some sticks.

Steve

stoves-request at listserv.repp.org wrote:
> Message: 1
> Date: Tue, 1 Jan 2008 21:45:05 +0200
> From: "Philip Lloyd" <plloyd at mweb.co.za>
> Subject: Re: [Stoves] Efficiency of clean fuel
> To: "'Discussion of biomass cooking stoves'"
> 	<stoves at listserv.repp.org>
> Message-ID: <001501c84cae$dbf02cb0$6500000a at private95a3azq>
> Content-Type: text/plain;	charset="us-ascii"
>
> I don't recall a proposition that "an electric hob transfers 40% of the
> thermal power into the pot." 
>
> What we have measured is an 80+/-1% efficiency of transferring electrical
> energy received by the hob into thermal energy in the pot.  This efficiency
> was measured with a voltmeter and wattmeter on the electrical feed to the
> stove, and the mass of water turned to steam during boiling, at close to sea
> level. The hob was a simple resistance element coiled into a spiral, such as
> is widely available as a cheap cooking device, and drew about 0.9kW at peak
> power.  The pot was a simple, flat-bottomed aluminum pot.
>
> For a power station at 37% thermal efficiency, and losing 8% of the
> electrical energy in transmission and distribution, that works out as 27.2%
> overall efficiency from heat energy supplied at the power station to heat
> energy into the pot, which is better than most.
>
> Hope that clarifies things!
>
> Happy New Year.
>
> (Dr)Philip Lloyd
> Energy Research Centre
> University of Cape Town
> Private Bag Rondebosch 7701
> South Africa
> Tel +27 (0)21 650 3896
> Fax +27 (0)21 650 2830
>
> -----Original Message-----
> From: stoves-bounces at listserv.repp.org
> [mailto:stoves-bounces at listserv.repp.org] On Behalf Of andrew
> Sent: 31 December 2007 03:52
> To: Discussion of biomass cooking stoves; bioconversion at listserv.repp.org
> Subject: [Stoves] clean fuel
>
> On Sunday 30 December 2007 16:57, Tom Miles wrote:
>
> In deference to Paul I'll attempt to move this bit of the discussion to
> [biconversion], though it will still reference the [stoves] thread. All such
> attempts have failed in the past because that list hasn't achieved critical
> mass and it spans a broad spectrum that people already discuss on other
> forums.
>
> I think establishing the relative total efficiencies of competing
> technologies is relevant to [stoves], especially following Sharon Gordon's
> recent query. With Philip Lloyd's proposition that an electric hob transfers
> 40% of the thermal power into the pot and Steve's 30% grid delivery from a
> thermal power station (inc transmission losses) that gives an overall 12%,
> doesn't even a 3 stone fire beat that?
>