[Stoves] [biochar] [biochar-stoves] A review of chronological development in cookstove assessment methods: Challenges and way forward

Thu Nov 26 05:53:25 CST 2015

Prof Lloyd

One of the academics in my department, Angus Campbell, is working on city farming and has provided the following information which might have answers your question:

“The most comprehensive study of biochar is Biochar for Environmental Management, 2009 by Johannes Lehmann, Stephen Joseph: https://www.routledge.com/products/9781844076581

Unfortunately it is one of those crazily overpriced research books, but can try and request an inspection copy.”

I don’t know the book nor the research area, but hopefully it has information which is useful to you.

Kind regards

Chris

From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Philip Lloyd
Sent: 26 November 2015 12:41 PM
To: 'Discussion of biomass cooking stoves'
Subject: Re: [Stoves] [biochar] [biochar-stoves] A review of chronological development in cookstove assessment methods: Challenges and way forward

Dear All

I am seeking solid scientific information on the benefits of adding biochar to soil. I need, at very least, the results of controlled experiments on significant sized plots of yields over several years for at least one crop, with one plot untreated and the other treated, and preferably with three crops and several soil types.  I was certain some agronomist somewhere had done such tests, but I have been unable to locate them – all I can find is uncontrolled tests on very small areas, and of very short duration with uncharacterized soils.

Help needed!

Prof Philip Lloyd
Energy Institute
Cape Peninsula University of Technology
PO Box 1906
Bellville 7535
Tel: 021 959 4323
Fax: 086 778 0257
Cell: 083 441 5247
PA: Nadia 021 959 4330

From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Crispin Pemberton-Pigott
Sent: 26 November 2015 01:31
To: Stoves
Subject: Re: [Stoves] [biochar] [biochar-stoves] A review of chronological development in cookstove assessment methods: Challenges and way forward

Dear Frank and Julien

If you know the pyrolysis temperature is above, say, 550 C, is it true that the remaining char is 'representative' of the fixed carbon content of the fuel? How close is it? What temperature would you say is close enough to give a meaningful fixed carbon number?

Hirendra Chakbarti is punting a calculation method for ultimate analysis that requires the fixed carbon number. From what I see it requires drying it first because the moisture affects the final dry carbon mass. Still, a mathematical fix might deal with that.

My specific goal is the fixed carbon content of the original fuel which has a known moisture content, but nothing else save the total mass.

Thanks
Crispin

Dear Ron and Stovers,

My interest is controlling the fuel. This done by 1) collecting fuel like that being used in real World and 2) normalizing the energy value going to the secondary by using pyrolyze gases + (CO -> CO2) values.

I cannot determine any energy efficiency values because this is just one side of the equation. And you do not supply me with the values of this one side as I need them.

The value I am proposing is only useful for energy traveling to another location - secondary. Making char does not require energy, in fact it waste energy. And (bio-)char does not have useful energy, in fact the energy is locked up and cannot be used by soil microbes for 1000 years. So what I propose is not applicatable to what you are talking about and not intended to be so.

Your (bio-)char (not charcoal used for cooking) is not ‘energy’ locked up but should be referred to as carbon. Following the total carbon in the feedstock; separating it into available carbon and non-available carbon (TGA) for optimum then determining the amount actually made from your char-maker is more to what you want. And that being your efficiency values.

But in a World that is connecting fuel energy producing non-available carbon (biochar) and that biochar is made >90% carbon (DAF) I guess it would be ok to assign non-available carbon with an energy value and use in calculations. Lets see if we can do that:
1) we need total energy of the biomass fuel (dry weight)
2) using TGA we need energy of the total char (DAF)
We assume the char (DAF) is 90+% carbon and assign that an energy value.
3) We determine energy of the pyrolysis gases (total - char)
 4) So thats the total maximum amount of energy assigned to biochar that should be produced in your devise.
5) You run YOUR device and produce biochar. Ash  a subsample to determine the weight of biochar (DAF). Assign an energy value to it based on biochar (DAF) being >90% carbon.

Now you can calculate the efficiency of your device at producing biochar.

Note: If you have wood (dry) and you use the pyrolysis gases for something, you use the CO->CO2 gases for something and use the (Bio-)char left over for something then 100% of the energy in the wood is always used. You are left with efficiency determinations found (compared to that determined by TGA) for making biochar. But if making biochar is found less than expected so to be not very efficient then the non-biochar gases (CO -> CO2) went to join the pyrolysis gases and it still always = all adds up to 100%. You can’t go wrong!

Where you can go wrong is if after making the biochar you test it to see if it still has hydrogen and lots of oxygen left indicating not a good biochar and it is then wasted. This is bad.
But if still good for char cooking (due to some volatiles) you are now back to 100% efficiency. You can’t go wrong!

100% efficiency every time!

Love it!

Frank
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