[Stoves] stoves and credits again
Ronal W. Larson
rongretlarson at comcast.net
Wed Sep 27 08:57:16 CDT 2017
Lloyd and List: cc Drs Anderson and Bond
I I find nothing wrong with the arithmetic here. But I find the methodology and conclusion wrong.
2. Re methodology for TLUDs, it is generally not possible to do what Dr. Lloyd asserts - testing a stove alternatively back forth with and without char-making. The equations are designed to predict stove efficiency when it can’t be measured. There may be stoves that can do what he asserts, but I don’t know of any. Doing that testing will be a big help in this “equation debate”. The intent of the arithmetic in his second paragraph is to come up with a thermal efficiency number that allows comparison with stoves that only inefficiently make char. One key purpose of that comparison is for using the existing Tier system. This computation however should have nothing to do with the utility of a Tier system; that is a different topic. The issue here is one of accuracy of the computation.
3. Dr. Lloyd’s key assumption in “case 2” (not a measurement) below was for 29% char making. If that number had instead been 27%, he would have achieved the 30% of “case 1” almost exactly. A 2 % difference in one place leads to a 2.1% difference in another. To encourage others to get into this, I intentionally do not show all the intermediate steps, but I am sure Philip will tell us if this is so.
4. In the perfectly valid 2nd case, the calculated final 32.1% stove thermal efficiency would be the logical value to insert in Tier comparisons - not 30%. To repeat - the methodology that Dr. Lloyd correctly employs is directional - it has always been used to predict what you can’t measure. If you can measure the 30% you have no need for this equation.
5. As to Dr. Lloyd’s “no benefit” conclusion, I fail to see how any of the calculations allows that. From the standpoint of the person wanting charcoal, it is certainly preferable to have the world believe 32.1% rather than the arbitrary 30% for stove thermal efficiency.
6. I believe this answers Paul Anderson’s query also below.
7. I am working on a more general approach to this which can remove the objections of a negative sign in the denominator. This to answer Professor Bond’s concerns. It will be based on the observation that the objectionable (1-e2) is the same as (e1+io). And one can alternatively argue all this with inverting the basis equation to read e1/e3 = 1-e2 = e1+io.
8. Re the conversation with Professor Bond, this is to add that the ISO approach also has a document on Tiers - my main concern in this discussion. My promised material in #7 will cover that.
9. I am also promising a response to Crispin’s last message to me - where one part shows he is not understanding this important part of the “denominator equation”.
Anyone see anything wrong in the above? More coming.
Ron
> On Sep 25, 2017, at 3:29 AM, Philip Lloyd <plloyd at mweb.co.za> wrote:
>
> I carried out a thought experiment.
>
> In case 1, a cookstove burning wood boiled 5 litres of water at an energy efficiency of 30%. The useful energy provided was 5*4.186*(100-15) = 1779kJ. This required 5*4.186*(100-15)/0.3 = 5930kJ. If the as-fired wood had a LHV of 15MJ/kg, it would have needed 5930/15000 = 0.395kg wood
>
> In case 2, the same stove was operated to produce charcoal while also boiling 5litres of water. More wood would be needed, because not all the wood would be combusted – some would be left as char. If you fed 0.395kg wood to be turned into char at 29% efficiency, and the char had an LHV of 28MJ/kg, then the char would have an energy of 0.395*28000*0.29=3163kJ. The wood from which it was prepared had an energy content of 5930kJ, which was what was needed to boil the water in the absence of char production. So 5930-3163 = 2768kJ of additional energy* would be needed to boil the water if there was char production. At 15MJ/kg, this is 2768/15000 = 0.185kg extra wood, or an increase of 47% in the wood supply. The total energy supplied would then be 5930+2768 = 8698kJ. The energy efficiency of cooking would therefore fall to 1779/8698*100 = 20.5%, while the efficiency of char production would have been 3163/8698*100 = 36.4%. The system efficiency would have been 20.5+36.4 = 56.9%
>
> If you used the WBT formula, the efficiency of boiling with char production would have been 1779/(8968-3163)*100 = 32.1%. Given the measurement errors inherent in the WBT method, this would have been statistically indistinguishable from the efficiency with no char production – i.e. it would have shown no benefit to char production.
>
> Prof Philip Lloyd
> Energy Institute, CPUT
> PO Box 1906
> Bellville 7535
> Tel 021 959 4323
> Cell 083 441 5247
> PA Nadia 021 959 4330
>
> *This assumes that there is no endotherm in the pyrolysis of wood in the presence of air, and that all the pyrolysis products except the char burn to provide heat. There is evidence in the literature of no endotherm in the presence of air.
>
> From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org <mailto:stoves-bounces at lists.bioenergylists.org>] On Behalf Of Paul Anderson
> Sent: Sunday, September 24, 2017 11:27 PM
> To: Discussion of biomass cooking stoves
> Cc: ndesai at alum.mit.edu <mailto:ndesai at alum.mit.edu>; Andrew Heggie; Crispin Pemberton-Pigott
> Subject: Re: [Stoves] stoves and credits again
>
> Philip, Tom and all,
>
> Philip is mostly correct. Actually wood takes up (has) too much WEIGHT. Wood has 3 times (or more, if the char is poorly made) the ENERGY value of charcoal that could come from that char. But it has about 5 times the DRY weight of the char, plus there can be 20 to 50% moisture content to make the wood even heavier.
>
> And the charcoal has almost double (30 vs. 16) the energy content by weight, but char is so much lighter per unit of volume. So the trucks are buldging upward and sideways with the sacks of charcoal strapped to them. Weight of charcoal is not a problem for most transport.
>
> Apart from the transportation issue, I believe that the appeal of charcoal is that it does not smoke (not much). CO is invisible and deadly, but the people learn to cook on the balcony or keep some air flowing. And it does not turn the bottom of the pots black.
>
> Charcoal is an attractive fuel. Too bad it is made by processes that throw away 2/3rds of the energy. (So, let's promote TLUD stroves and collect the char for sale to the urban folks. Only one third of the cutting of wood/forest.)
>
> So, if 100,000 households (mainly in rural or peri-urban areas) would use TLUDs, the resultant char would equal to the energy needed for an approximately equal number of households (mainly urban) that would want to burn charcoal.
>
> Now that would be FUEL efficiency measured by communities, not by single stoves.
>
> Paul
>
>
> Doc / Dr TLUD / Prof. Paul S. Anderson, PhD
> Email: psanders at ilstu.edu <mailto:psanders at ilstu.edu>
> Skype: paultlud Phone: +1-309-452-7072
> Website: www.drtlud.com <http://www.drtlud.com/>
> On 9/24/2017 11:40 AM, Tom Miles wrote:
>> That's probably why charcoal use is increasing 5% per year in SSA compared with wood fuel at 1% per year.
>>
>> T R Miles Technical Consultants Inc.
>> tmiles at trmiles.com <mailto:tmiles at trmiles.com>
>> Sent from mobile.
>>
>> On Sep 24, 2017, at 8:50 AM, "plloyd at mweb.co.za <mailto:plloyd at mweb.co.za>" <plloyd at mweb.co.za <mailto:plloyd at mweb.co.za>> wrote:
>>
>>> Just a thought on Sub Saharan charcoal use. As Africa urbanizes, so it needs energy to cook. Wood takes up too much volume, and the roads are primitive. So it makes sense to use charcoal. A bicycle load will keep ten homes cooking for a week.
>>> The use of char oal has everything to do with logistics and nothing to do with the environment.
>>> Philip
>>>
>>>
>>>
>>> Sent from my Huawei Mobile
>>>
>>>
>>> -------- Original Message --------
>>> Subject: Re: [Stoves] stoves and credits again
>>> From: Nikhil Desai
>>> To: Ron Larson
>>> CC: Andrew Heggie ,Crispin Pemberton-Pigott ,Discussion of biomass cooking stoves
>>>
>>>
>>> Ron:
>>>
>>> What makes you believe that users of biomass-fuelled stoves are predominantly growers (of biomass)?
>>>
>>> Saw the figures for urban charcoal markets in Sub-Saharan Africa lately? Or looked at non-household cooking (in my view roughly 50% of cooking energy consumption worldwide)?
>>>
>>> Nikhil
>>>
>>> On Thu, Sep 21, 2017 at 10:54 PM, Ronal W. Larson <rongretlarson at comcast.net <mailto:rongretlarson at comcast.net>> wrote:
>>> Andrew and list:
>>>>>
>>>>
>>>> There appears to be a win win situation here and I gather there is
>>>> still a vast part of equatorial Africa where annual burning takes
>>>> place. However it brings me to another reason I like the idea, though
>>>> not the practicalities, of a householder-subsistance farmer being paid
>>>> a subsidy funded by the developed world. The trouble is I have a
>>>> parochial view and not a good worldview of what types of persons
>>>> depend on biomass fuelled stoves. Are they also predominantly growers?
>>>
>>> [RWL9: Yes to Andrew’s last question. I disagree with Andrew calling himself “parochial” - when he supports (as do I) the ethics of “a subsidy funded by the developed world”.
>>>
>>>
>>> [RWL10: Agree totally. And I think this is what will eventually kill the geoengineering technology that is often placed ahead of biochar - BECCS. In BECCS, as with “clean coal”, the CO2 from combustion (never pyrolysis) is placed, as liquid, deep underground. Major expenses needed to protect the world’s soil are not needed for biochar. Soil quality is closely linked to carbon content - and biochar does this with no penalty - while apparently being the cleanest and most efficient of all possible solid-fuel stoves.
>>>
>>> `Andrew - thanks for your above rebuttal to Crispin.
>>>
>>> Ron
>>>
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> Stoves mailing list
>>>
>>> to Send a Message to the list, use the email address
>>> stoves at lists.bioenergylists.org <mailto:stoves at lists.bioenergylists.org>
>>>
>>> to UNSUBSCRIBE or Change your List Settings use the web page
>>> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org <http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org>
>>>
>>> for more Biomass Cooking Stoves, News and Information see our web site:
>>> http://stoves.bioenergylists.org/ <http://stoves.bioenergylists.org/>
>>
>>
>> _______________________________________________
>> Stoves mailing list
>>
>> to Send a Message to the list, use the email address
>> stoves at lists.bioenergylists.org <mailto:stoves at lists.bioenergylists.org>
>>
>> to UNSUBSCRIBE or Change your List Settings use the web page
>> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org <http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org>
>>
>> for more Biomass Cooking Stoves, News and Information see our web site:
>> http://stoves.bioenergylists.org/ <http://stoves.bioenergylists.org/>
>>
>
> _______________________________________________
> Stoves mailing list
>
> to Send a Message to the list, use the email address
> stoves at lists.bioenergylists.org <mailto:stoves at lists.bioenergylists.org>
>
> to UNSUBSCRIBE or Change your List Settings use the web page
> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org <http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org>
>
> for more Biomass Cooking Stoves, News and Information see our web site:
> http://stoves.bioenergylists.org/ <http://stoves.bioenergylists.org/>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20170927/7c1d1323/attachment.html>
More information about the Stoves
mailing list