[Stoves] ETHOS 2013: Where is the New Data on Stove

Crispin Pemberton-Pigott crispinpigott at gmail.com
Wed Nov 28 21:52:52 CST 2012


Dear Ron

 

I followed your general point and wonder if you could consider these ‘typical’ examples and then fine tune the request.

 

Here is a wood analysis (without dilution by moisture)

 


FUELS:

Wattle


Ash %

               0.50 


Sulphur %

               0.04 


Hydrogen  %

               6.50 


Carbon %

            49.46 


Oxygen  %

            43.00 


Nitrogen %

               0.50 


Total %

          100.00 


HHV

            18.70 


LHV

            17.38 


DAF HHV

            18.79 


C:H ratio

               7.61 

 

 

And here is a Charcoal analysis:

 


FUELS:

Charcoal


Ash %

             2.00 


Sulphur %

             0.10 


Hydrogen  %

             1.69 


Carbon %

           83.00 


Oxygen  %

           13.11 


Nitrogen %

             0.10 


Total %

         100.00 


HHV

           29.80 


LHV

           29.46 


DAF HHV

           30.41 


C:H ratio

           49.11 

 

So the assumption (which is a big one but let’s go with it) is that the char represents the difference between burning whole fuel and leaving some charcoal.

 

Then the conversion of that char into a CO2 saving (we can come back to the CO as CO2e) is the difference between the char % in the remaining fraction and the original (dry) fuel analysis. Let’s say it was 83% v.s. 50%.

 

So 1 kg of wood = 500 g of C

1 kg of Char = 830 g of C

 

The difference is 1.66 times the C in the char mass as an equivalent mass of dry fuel.

 

CCHAR = 1.66

CWOOD

 

As there is always some mass of moisture in the wood and none in the char, it is fair to include the moisture, let’s say 15% and use the formula:

 

____CCHAR _____=          830         = 1.95 for a factor of about 2.

CWOOD*(1-H2O%)    500*(1-0.15)

 

Weighing the remaining char, say 250 g, you multiple by 2 to get 500 g of wood equivalent (at 15% moisture). 

 

By not burning that 250 g of char, you have effectively not burned 500 g of that particular fuel when viewed from the perspective of CO2 emitted.

 

Because most stoves made at least some char, the same calculation would have to be done for both stoves to get a fair comparison. So you could have two methods: either take a difference of char only and use the Carbon content of the char to directly calculate an amount of CO2 avoided, or express it as a mass of moist fuel not burned, deducting it from the total burned. Normally the CO2 emitted is calculated from the mass of fuel burned so it might fly father with the Carbon traders.

 

Regards

Crispin

 

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