[Stoves] Stoves at ETHOS

[IPC]

Dear Crispin

Yes - nice insight.  However, the efficiency of use has some role.
Electricity used for cooking is around 80% efficient. You are doing well
with a thermal cookstove to get above 40%, particularly if (as with coal)
you need some form of igniter.  So you don't really win.  Where you do win,
however, is when you take into account the capital needed to generate
electricity.  Put it at around $1300/kW, and throw in another $200 for
transmission and distribution, and you can buy quite a lot of cookstove and
fuel.  We have a paper on the possible benefits of converting 5 million
housholds to cooking on safe paraffin stoves - being prepared for the
conference on the Domestic Use of Energy next March.  It pays!

Best regards

(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
e-mail philip.lloyd at uct.ac.za 



-----Original Message-----
From: stoves-bounces at listserv.repp.org
[mailto:stoves-bounces at listserv.repp.org] On Behalf Of Crispin
Pemberton-Pigott
Sent: 29 December 2007 10:44
To: 'Discussion of biomass cooking stoves'
Subject: Re: [Stoves] Stoves at ETHOS

Dear Paul

Other stoves - well I think it would be useful to see the metal copy of the
Maputo Ceramic Stove. It travels well and can be made pretty easily by
anyone who can make a JIKO.  It works in a very different way so people
involved in fuel efficient charcoal stoves might find the design principles
interesting.

As you all know it is pretty hard to bring anything heavy.

I really look forward to seeing the TLUD and talking about fan stoves for
charcoal and what it might involve.  There is a really interesting
cub-market there: people who have small amounts of electricity and very low
cost coal. I don't see why they should not have good stoves too!

There was a plan in a city to make electricity available for people to heat
with, the idea being that the small scale burning of coal is so polluting
that the system inefficiencies of electricity would more than compensate for
it.

So I did just a little math to see.  Distilled it looks like this:

If you burn coal with a total emission output of 2.5 times that emissions of
a bit power station (per kg of coal burned) and your stack losses are nil,
the effect on the community is about the same, unless the power station is
far away of has an extremely tall chimney.

Suppose the emissions are about the same (a really good fan stove burning
well selected coal).  The total emissions are much less because a power
station is only 35-40% efficient at turning coal into electricity.  I agree
that fuel cells working directly may change that, but not soon.

So, what stack losses (hot gases) can we afford?  The thermal efficiency of
the stove/heater can be as low as 40% if the emissions are no higher.  Very
interesting.  I found that the emissions from the big power plants in
Ulaanbaatar are not all that marvellous anyway.  

So that is the target: work out the net heat delivered per unit of gas
emissions, and have the total package be better than the big power stations
and you have a case to make to the city.

With the same emissions, 75% system efficiency and burning a locally
available coal, the total cost and effect on the environment is more
attractive than electric heating.

Regards
Crispin

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