[Stoves] Differences in stove testing ---- was Re: ETHOS 2017 agenda and logistics

Tue Feb 7 05:54:06 CST 2017

Dear Andrew

I think it is time you and Ron take a break from putting words in my mouth.

"Ronal sees that as an attribute you don't and see it as a waste
without value in energy or cash terms."

I have NO problem with recognising the value of the char and if you will recall, I am the one who posted years ago how to correctly credit the various energy destinations and also how to correctly rate the performance of a pair of stoves. Now we have a stove available from Nurhuda that has two distinct burning phases.

I have NO problem determining and reporting the energy or mass attributes of char. I have proposed metrics for this.

I do not accept saying that a stove that uses ten kg of wood to cook uses less than ten kg. That is my objection.

Paul's objection to this is calling the char 'waste' as far as the char making stove is concerned. ‎Yet from a fuel consumption point of view it is.

Ron's objection is calling the energy in the char a 'loss'. Yet is is as far as the firs stove in a putative chain of stoves is concerned.

You can call the char whatever you like. But it's mass and it's energy do not reduce the amount of fuel needed fromm the source.

Prof Lloyd has just explained, clearly, twice, that to rate these additional 'benefits' all of which involve energy that originates from the fuel fed, is done by putting them in the numerator, over the total energy in the fuel fed, the 10 kg.

Ron feels that my position on this is in a minority, as if that makes a difference. Prof Lloyd confirmed that it is a majority position in the group of Experts writing the ISO standard for cooking stoves.

There are still a couple of proponents of the 'char-deducted' cooking efficiency metric as per WBT. ‎Challenged to find another single example of this formula none could be located. Why? Because that is not how to calculate the energy benefit from an energy supply.

It would be helpful is the char making stoves were evaluated as part of a larger system so that all the co-benefits could be ‎seen in the larger context.

Here are some ideas:

Fuel is consumed.
Energy is released
Cooking is accomplished
Energy needed to convert the food into cooked food is an energy gain
Heat past the pot is a cooking energy loss
Char is produced
Char energy is thereby retained
Cooling the char is an energy loss
Unrecovered ‎char in the ash is a char loss
Cooling the ash in an energy loss
Cooling the stove after cooking is an energy loss

If you desire space heating, several of these energy paths are changed from losses to space heating gains. They are not converted to cooking efficiency gains.

If you want to know how much of the heat released gets transferred to the pot, you are asking for the heat transfer efficiency. Perfectly reasonable request. You have to determine all the energy in the residual solids, not just 'a major portion' of the char or the answer won't be accurate.

Regards
Crispin

On 7 February 2017 at 03:51, Crispin Pemberton-Pigott
<crispinpigott at outlook.com> wrote:
> Dear Andrew
>
> Small correction, the energy that is 'releasable' form the fuel is in the denominator. It is also called embedded ‎energy and energy in the fuel fed and so on.
>

It's been a long series of threads but I remember the term being
released, also I haven't discussed this denominator as I haven't
followed the maths and am no longer clear what equation is being
wrangled over.

> If I buy 10 litres of gasoline and burn 5 and let the other five leak away, I cannot claim I only consumed five. I consumed five and wasted the other five.
>

I agree if having a leaky fuel tank were  part of the normal use of
the stove and so waste was inevitable, here we are talking of a co
product that may be used  in a further cooking (or power generation
project  as recently considered by the indefatigable Dr TLUD and
discussed by Alex and myself here 15 years ago)

> The fact that wasted fuel has energy doesn't reduce my wastefulness.

Only if it is truly wasted
>
> If I collected the drips in a cup and used in somewhere else, ‎i recoup some of the loss. But the original consumption is still 10 litres.

No it isn't because you still have the drips to use elsewhere
>
> Paul is describing a systems approach in which there are multiple stoves or 'energy devices'. The rating of each portion of that system is what we are doing with a stove test. ‎There might be three stoves in a chain using some input fuel. The rating of the fuel consumption and energy delivered on the first one is not altered by what happens later with the others.

I'll pass on that as the meaning is not clear to me.

It's semantics, you may as well say that  flying only  needs the fuel
necessary to overcome drag in going forward and not count  the effort
needed to throw air downward to counteract the tendency for the plane
to fall out of the sky.

A TLUD stove when operated at certain air flows co produces char,
Ronal sees that as an attribute you don't and see it as a waste
without value in energy or cash terms.

I see the value in a clean flame but until I get my head around the
consequential costs of pollution  I cannot put a value on it any more
than I can value attempts to counter CO2 increases in the atmosphere
or oceans.

Now I get my wood for no payment but a small amount of effort ( plus
fuel in my saw and transport including wear and tear) in converting
it. I burn it to ash, if someone comes along and offers me sufficient
money for co producing char  for doubling my throughput and effort I
can make a simple decision of whether it's worth my while and I may
take into consideration that I'm using a technique that  reduces the
outdoor air pollutionin my neigbourhood.

Andrew

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