[Stoves] [biochar] Energy / fuel / biochar DATA from Kenya Re: FW: REQUEST for complete sets of raw data of cookstove tests.

Wed Apr 24 16:07:10 CDT 2013

Dear Paul

I did a search for the Article you reference below, but could not find it. Other Articles at the SciDirect Site cost $35.95 each. http://www.sciencedirect.com/science/journal/09619534/35/11  My comments are on yours, and the Abstract you present...

  ----- Original Message ----- 
  From: Paul Anderson 
  To: Discussion of biomass cooking stoves 
  Cc: Crispin Pemberton-Pigott ; biochar at yahoogroups.com 
  Sent: Wednesday, April 24, 2013 3:27 PM
  Subject: [biochar] Energy / fuel / biochar DATA from Kenya Re: [Stoves] FW: REQUEST for complete sets of raw data of cookstove tests.

  Dear Stovers who want truth in reporting about stove efficiency.

  # Just what is "the truth in reporting about stove efficiency"? Neither you nor the abstract present any truths about "stove fuel efficiency" for various stoves.
  * What are the typical stoves in use now in Kenya, and what are their fuel efficiencies?
  * What is the fuel efficiency of pyrolitic stoves that could be used there?
   * What is the fuel efficiency of well designed conventional stoves that can burn crop residues, shrub and tree litter without producing significant char?
  * Would Kenya Farmers be bettter off if they returned the crop residues to their soils to build organic matter? 

  The title and abstract below seem to be a good example to illustrate what happens when stoves can use fuels other than wood and can produce charcoal (for burning or for biochar).

  # I would suggest not.. A pyrolytic stove producing char is certainly better than a three stone fire, but there is nothing to show how a pyrolytic stove producing char would compare to a to a "full combustion stove" designed to burn equivalent fuels.

  This is not my data, and not my stove design.   How do we get this type of "stove IMPACT" included into stove testing? 

  # IMPACT is IMPACT and Stove testing is Stove Testing. They are two very different subjects. A good place to start would be to have a stove testing protocol that showed the fuel efficiency of various stoves, so that where fuel efficiency was the factor of prime importance, the most fuel efficient stove could be selected. With a science based stove testing protocol, the Customer could select the stove that best met his IMPACT requirements.

    I think the word IMPACT can carry the same weight as efficiency. 

  # If you feel IMPACT can carry the same weight as efficiency, you provide an excellent reason for the need for science based stove testing. 

    "ENERGY efficiency" should be reported.    "Fuel impact" might be an additional result to report.

  # I would strongly disagree with you for reasons as follows: "Energy Efficiency" is only a measure of the percentage of "Corrected fuel energy" that "enters the pot" after  subtracting the energy in the unburned char from the energy in the fuel supplied. "Fuel Efficiency", on the other hand, tells the Stove Customer the efficiency of fuel utilization to "get the cooking job done." The stove with the highest fuel efficiency will absolutely require the least fuel input.The way to have the biggest "fuel impact" is to favour the use of stoves with highest fuel efficiency.

  # Note that Paul Oliver's presentation favouring the use of TLUD's in Vietnam shows that there is a huge surplus of agricultural residue, and the market for char and heating to displace LPG  energy is such that it is profitable for the Home Owner to use TLUD's. The Article you reference provides nothing solid, as did Paul Oliver.

  # Note that the last sentence of the Abstract you provide:
  "The introduction of a first-generation pyrolytic cook stove reduced wood
  energy consumption by 27% while producing an average of 0.46 Mg ha-1 y-1 of biochar.  "
   is especially fluffy. 
  1: A new stove design is being compare to a stove that might be as inefficient as a 3 stone fire, with no windscreen, burning semi-green wood. 
  2: They don't tell us anything about the fuel used in the pyrolytic stove... perhaps they burned agricultural waste. Regardless of its efficiency, it would still save wood. 
  3: They don't give any indication that they have tested appropriately designed "full burn stoves" on wood and on agricultural waste, so there is no reason to believe that pyrolytic stoves are "the best for the circumstances."

  Best wishes,

  Kevin
  Paul

    "Biomass availability, energy consumption and biochar production in rural households of Western Kenya"
    Biomass and Bioenergy Vol 35 (2011) pp.3537-3546
    Dorisel Torres-Rojas a, Johannes Lehmann a,*, Peter Hobbs a, Stephen Joseph b,
    Henry Neufeldt c
    a Department of Crop and Soil Sciences, Cornell University, 9090 Bradfield Hall, Ithaca, NY 14853, USA
    b University of South Wales, NSW 2052, Australia
    c World Agroforestry Center (ICRAF), Nairobi, Kenya

    Abstract
    Pyrolytic cook stoves in smallholder farms may require different biomass supply than
    traditional bioenergy approaches. Therefore, we carried out an on-farm assessment of the
    energy consumption for food preparation, the biomass availability relevant to conventional
    and pyrolytic cook stoves, and the potential biochar generation in rural households of
    western Kenya. Biomass availability for pyrolysis varied widely from 0.7 to 12.4 Mg ha1 y1
    with an average of 4.3 Mg ha1 y1, across all 50 studied farms. Farms with high soil fertility
    that were recently converted to agriculture from forest had the highest variability
    (CV ¼ 83%), which was a result of the wide range of farm sizes and feedstock types in the
    farms. Biomass variability was two times lower for farms with low than high soil fertility
    (CV ¼ 37%). The reduction in variability is a direct consequence of the soil quality, coupled
    with farm size and feedstock type. The total wood energy available in the farms (5.3 GJ
    capita1 y1) was not sufficient to meet the current cooking energy needs using conventional
    combustion stoves, but may be sufficient for improved combustion stoves depending
    on their energy efficiency. However, the biomass that is usable in pyrolytic cook stoves
    including crop residues, shrub and tree litter can provide 17.2 GJ capita1 y1 of energy for
    cooking, which is well above the current average cooking energy consumption of 10.5 GJ
    capita1 y1. The introduction of a first-generation pyrolytic cook stove reduced wood
    energy consumption by 27% while producing an average of 0.46 Mg ha-1 y-1 of biochar.

Paul S. Anderson, PhD  aka "Dr TLUD"
Email:  psanders at ilstu.edu   Skype: paultlud  Phone: +1-309-452-7072
Website:  www.drtlud.com

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