Ian,
I respond to your statement:
“Maybe we could start by agreeing that while 2.5t CO2/t biochar is the ‘right’ number to promote the use of biochar the delivery of this as a target will be different from each corner of the tent ? Some will be as high as 4, some will be less than 1. “
By chemical weight, 1 unit of C (atomic wt. 12) would become part of 3.66 units of CO2 (wt = 12 + 2×16 = 44 —— 44/12 = 3.666666) (Most of us know that.) So any value above 3.67 is hard to imagine and should be challenged.
3.0 t CO2 per 1 t of biochar would be 82%
2.5 t CO2 per 1 t of biochar would be 68%
2.0 … …………….. would be 54%
1.5 ……………………….. would be 40%
1.0 ………………………….. would be 27%
0.5 ……………………………would be 14%
0.2 might cover the case of boiler fly ash IF it contained 5% carbon that is pure and stable. The huge volume of ash from boilers is what can add up to some significant amounts of carbon. But is it biochar? It is sequester-able carbon that represents CO2 removed from the atmosphere by plants?
There can be many variations of biochar. Ian mentions “four corners of the tent” the covers the range of biochar production methods. The variation in stable carbon content is in relation to the methods AND to the consistency of the processing with each method.
“Burners” can produce a lot of ash and very little residual carbon
The rigorous pyrolysis devices including TLUDs can adhere to levels of 70 to 85% stable carbon.
In devices that are flame-cap or retort technology, there is a constant risk that the desired high heat of pyrolysis did not reach all of the biomass (as in thick pieces or biomass that was shielded by other biomass.) Careful operational control can avoid this problem, but errors are difficult to detect when all of output is black on the outside. Such pieces of “less than pyrolyzed” biomass will contain less of stable carbon even though its weight is a higher percentage of the original weight of the biomass.
Good biochar should probably have a content of FIXED carbon, or RECALCITRANT carbon , or STABLE carbon of 70% to 85% of the dry weight of the charcoal (biochar). The remaining percentage is some combination of ash (inert chemicals such as silica) and what is called VOLATILE matter or MOBILE matter. NOTE: Volatile is a word borrowed from the analyses of coal which is destined to be burned and where heat is applied to drive it off. But biochar (charcoal) that is in soil or a test tube at ambient temperatures can also lose some of this non-stable carbon through 1) dissolved in water and washed away 2) eaten by microbes, and 3) vaporization (being volatile to become a gas and escape). So Mobile is a better term than Volatile because biochar is going into soil where it will never again see temperature of even 100 deg C,
If the “charcoal or bioichar” is heated to higher temperatures that drive off volatile materials, the Stable carbon percentage can go higher (to maybe 95%, but the ash is not being removed), but that would be called activated carbon, and not biochar.
Stable carbon is quite pure, mainly as graphene sheets. THAT STABLE carbon is what Ian was discussing. 2.5 t out of 3.66 t would be 68%. We in the industry of biochar should not over-value or make false claims. So that would be a nice, usually conservative number for us to use.
If the char is known to have been poorly made or from a feedstock such as rice husks that are known to have high silica content, then some conversion number lower than 2.5 would be advisable to use.
1.83 weight units of CO2 would be 50% of the maximum possible of 3.66 units. If the stable carbon percentage is lower than that, it is debatable if it should be called biochar or even charcoal.
If you have not already seen it, or have forgotten, or if you want to reference something other than this email message, you can check out much of this info in the 2009 (Version 2, October 2009) document “All biochars are not created equal, and how to tell them apart” by McLaughlin, Anderson, Shields and Reed. Found at:
www.drtlud.com/wp-content/uploads/2012/08/All-Biochars-Version2-Oct2009.pdf
Comments and corrections to the above are most welcome.
Paul
Doc / Dr TLUD / Paul S. Anderson, PhD — Website: www.drtlud.com<www.drtlud.com/>
Email: psanders@ilstu.edu<mailto:psanders@ilstu.edu> Skype: paultlud
Phone: Office: 309-452-7072 Mobile & WhatsApp: 309-531-4434
Exec. Dir. of Juntos Energy Solutions NFP Go to: www.JuntosNFP.org<www.juntosnfp.org/>
Inventor of RoCC kilns for biochar and energy: See www.woodgas.com<www.woodgas.com>
Author of “A Capitalist Carol” (free digital copies at www.capitalism21.org<www.capitalism21.org/>)
with pages 88 – 94 about solving the world crisis for clean cookstoves.
From: main@Biochar.groups.io <main@Biochar.groups.io> On Behalf Of Ian McChesney via groups.io
Sent: Saturday, September 19, 2020 12:11 AM
To: main@Biochar.groups.io
Subject: Re: [Biochar] GHG Targets for Biochar Processes
Tom, Bob …
Understand the requirement for simple GHG metrics for biochar. In similar industries (renewables) these have been key to policy/public understanding and acceptance of innovation and change. The difficulty for biochar is that the context in which biochar is produced and used determines most of the relevant numbers $/t, $/tCO2, CO2/acre etc, not the product itself.
And the biochar tent has at least ‘four corners’. Bob describes two of these, the ‘Burners’ and the ‘Pyros’, but there also has to be space for the ‘TLUDs’ and the ‘Kontikis’ and possibly for others too. Linking numbers to ‘technology’ is potentially divisive, but from an engineering perspective there needs to be a ‘basis’ – t/yr, CO2/t, t/ha/yr etc – on which numbers can be generated.
PyCCS is an attempt to leapfrog this. Intuitively burying carbon is better than burning it. Nevertheless, communicating this in a LULCC / UNFCCC REDD+ paradigm and interpreting it for markets and investors still needs the these comparative numbers.
It is very easy to go round in circles on this one. Maybe we could start by agreeing that while 2.5t CO2/t biochar is the ‘right’ number to promote the use of biochar the delivery of this as a target will be different from each corner of the tent ? Some will be as high as 4, some will be less than 1.
Ian
_._,_._,_
________________________________
Groups.io Links:
You receive all messages sent to this group.
View/Reply Online (#28254)<Biochar.groups.io/g/main/message/28254> | Reply To Group<mailto:main@Biochar.groups.io?subject=Re:%20Re%3A%20%5BBiochar%5D%20GHG%20Targets%20for%20Biochar%20Processes> | Reply To Sender<mailto:ian.mcchesney@gmail.com?subject=Private:%20Re:%20Re%3A%20%5BBiochar%5D%20GHG%20Targets%20for%20Biochar%20Processes> | Mute This Topic<groups.io/mt/76805223/3503606> | New Topic<Biochar.groups.io/g/main/post>
Mute #ghg<Biochar.groups.io/g/main/mutehashtag/ghg> | Mute #corcs<Biochar.groups.io/g/main/mutehashtag/corcs> | Mute #co2e<Biochar.groups.io/g/main/mutehashtag/co2e>
Your Subscription<Biochar.groups.io/g/main/editsub/3503606> | Contact Group Owner<mailto:main+owner@Biochar.groups.io> | Unsubscribe<Biochar.groups.io/g/main/leave/8196064/2089773711/xyzzy> [psanders@ilstu.edu]
_._,_._,_