Unique Biochar Phenomena
Hugh McLaughlin, PhD, PE
www.acfox.com
November 23, 2014 @ Tufts

Despite their artistic pretensions,
sophistication, and many
accomplishments, humans owe
their existence to a six-inch layer
of topsoil and the fact that it rains.
– anonymous

Theories for Ancient Practices
• Prior to steel axes, fire was the main tool for
modifying the landscape and clearing land
• Staple crops tend toward starches, which
require significant potassium and phosphates –
which have to be added for sustained field
productivity (and this field was a lot of work)
• Field preparation by transporting water
vegetation, like palm leaves, then “cool
burning” to release fertilizers into soil

This is the tree as it grows.
About one half of the carbon
dioxide uptake results in
additional carbon atoms in
biomass
This is when biomass dies
and becomes detritus: such
as leaves and tree death
This is due to microbial
breakdown of dead biomass –
95% in one to twenty years

200 CO2
200 C
<100CO2>
100C
Fate of Reduced “Fixed” Carbon
- After the plant takes care of
energy requirements of procuring a
balanced diet, the excess carbon is
directed to seeds, biomass growth or
stored as sugars for the next season.
- Sugars are excreted into the soil
biota in exchange for plant nutrients
(NPK and micro-nutrients).
- If NPK are available, the plant
does not “waste” sugars on soil.
microbes and puts that carbon into
plant priorities = more plant growth
-Without plant sugars, soil microbes
attack each other and soil carbon
decreases, leading to sterile soil.

Pyrolysis and Carbonization
convert biomass into biochar:
one half of the carbon atoms
are released as volatiles and
one half converted to biochar
The volatiles contain carbon
atoms that the tree removed
from the atmosphere as it
grew = carbon neutral
A minority of biochar is
slowly oxidized by soil
microbes; the majority
is stable for hundreds
to thousands of years
<10CO2>
40C remains in
stable in the soil
200 CO2
50C
<50CO2>

Climate
Civil
Disobedience
Carbon
Time-out

Biochar: “invented” 600 million years ago by Mother Nature

From: http://www.techtp.com/Torrefaction for High Quality Wood Pellets.pdf, page 7 of 36
Figure 2: Wood Physical Structure – from tree to molecules of lignin & sugars

From: http://www.techtp.com/Torrefaction for High Quality Wood Pellets.pdf, page 7 of 36
Figure 2: Wood Microscopic Structure – molecular mixtures at the atomic scale

Pyrolysis & Carbonization Reactions of Wood
@300C: Below = Torrefied Wood Above = charcoal & biochar
Hemicellulose Lignin Cellulose
D
Extensive
Devolatilisation
and
carbonisation
(E)
Limited
devolatilisation
and
carbonisation (D)
depolymerisation
and
recondensation
(C)
drying (A)
E
D
C
A
E
D
C
A
glass transition/
softening (B)
300
250
200
150
100
Temperature (°C)
Hemicellulose Lignin Cellulose
300
250
200
150
100
Temperature (°C)
TORREFACTION

Hardwood Pellets: Dried, Carbonized 200C to 300C

Amorphous Graphite = Domains of Graphene
From page
8
Figure 3: Development of local Graphene domains during carbonization

Page 3 of J. Phys.: Condensed Matter 19 (2007)
9
Figure 4: Development of porous 3-dimension structure during carbonization

Figure 1: Yield and Adsorption Capacity of Lab Chars
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
10%
9%
8%
7%
6%
5%
4%
3%
2%
1%
200 300 400 500 600 700 800 900
Heat treatment temperature Celsius
Char yield as wt % of dry biomass
0%
Adsorption capacity as wt % R134a at 100C
Yield
Ads @ 100C

Pivotal Biochar properties:
Short-term Effects are due primarily to
• Ash Content – due to pH impact
• Mobile Matter – due to stimulating parasitic soil
microbes, which compete for nitrogen, but
sometimes any microbes are better than none
Long-term Effects are attributed to only the
• Resident Matter – because it
• Adds Volume with high porosity to the soil
• Increases Cation Exchange Capacity
• Introduces significant Adsorption Capacity

How does Biochar work in the Soil?
• Biochar works in conjunction with the
existing soil, crop and climate.
• Biochar helps “soil” go back to being soil.
• Improved Moisture Dynamics – high & low
• Improved Nutrient Retention (N, P, K)
• Improved Microbe survival during drought
• Improved Plant-Microbe synergisms

This begs the question:
How does Resident Matter accomplish
the following in the Soil?
• Improved Moisture Dynamics – high & low
• Improved Nutrient Retention (N, P, K)
• Improved Microbe survival during drought
• Improved Plant-Microbe synergisms
- and why does it depend on Biochar
Porosity, CEC and Adsorption?

How does Resident Matter accomplish
the following in the Soil?
• Improved Moisture Dynamics – high & low
Two different moisture regimes,
with three different mechanisms:
– High moisture in tight soils (flooding in clays)
– High moisture in loose soils (flooding in sand)
– Low moisture in all soils
• desiccating or drought conditions

- applies to all micro-porous media including chars
- Also Bulk Density or the box of corn flakes
- this is the density of the individual corn flakes
-this is the density of the corn flake “molecules”
or the corn flake skeleton without vapor volume

Calculating the “density, porosity, voidage”
of a typical biochar (a good one…)
• Apparent Density = 250 kg/cubic meter
• Skeletal Density = 1500 kg/ cubic meter
– Skeleton = 250/1500 = 1/6 cubic meter
– Total voidage = 1 – 1/6 = 5/6 cubic meter
• Assuming 1/3 inter-particle voids
– Space between particles = 1/3 cubic meter
– Space inside particles = 5/6 – 1/3 = 1/2 m3

Summary: Biochar is 83% voidage and
17% graphitic skeleton
• 33% of the volume is between particles –
this improves soil drainage and aeration
• 50% of the volume is inside particles – this
volume is available to store bulk water
This available volume improves overall soil
properties during excess moisture
– but what about desiccating soil conditions?
That requires ADsorption of the moisture

Mechanis
m

Linear
isotherms

Non linear
isotherms

How does Resident Matter accomplish
the following in the Soil?
• Improved Nutrient Retention (N, P, K)
This is the CEC = Cation Exchange Capacity property
Biochar has both Cation and Anion Exchange capacity
- Exchange Capacity is due to non-graphitic organic
side chains, oxidized to organic acid functionalities
and organic bases due to bound nitrogen molecules
- Adsorption of Humic Acids also increases EC

How does Resident Matter accomplish
the following in the Soil?
• Improved Microbe survival during drought
• Improved Plant-Microbe synergisms
Microbes need two things to survive: food and water
- Biochar adsorbs water and water soluble
organics via isotherms – and desorbs them when
background levels are below “equilibrium”

Freshly made Biochar is like raw Ground Beef;
is it food? – not yet
Steps to preparing biochar for optimal soil benefit: C-C-I
- Conditioning: equilibrate with soil moisture properties
- pH effects, total dissolved solids (salts), liming
- desorb soluble sugars and other mobile matter
- Charging: equilibrate with soil fertilizer levels
- in balance with annual fertilizer fluxes
- Inoculating: Biasing the Soil Microbial Populations
- this may not be necessary or even work
All of which happens during composting or given enough time

Make Biochar,
and save your world

Options for obtaining Biochar
• You can buy it – but from who?
– Some charcoals are good biochars, some are
BAD – and all need to be tested
• You can make it
– For “gardening”, TLUDs work best
– The other approach is “Retort” processes
– Equipment is coming to the market – slowly
• Example: Adam Retort – about 350 kg/batch

How does wood burn?
• Wood, consists of hemicellulose, cellulose and
lignin
– Hemicellulose gasifies at 250 – 300C
– Cellulose splits into char and volatiles between 300C
and 450C
– Lignin splits into char and volatiles between 300C and
750C
– Volatilization cools the remaining solid, but the gases
burn and generate radiant heat (yellow to blue light)
– Eventually, oxygen can react with the remaining char to
make CO2, H2O and ash, plus more heat (red light)
– Putting it all together, we have:

Figure 1: Yield and Adsorption Capacity of Lab Chars
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
10%
9%
8%
7%
6%
5%
4%
3%
2%
1%
200 300 400 500 600 700 800 900
Heat treatment temperature Celsius
Char yield as wt % of dry biomass
0%
Adsorption capacity as wt % R134a at 100C
Yield
Ads @ 100C

Any Volunteers for running a Earth mound Kiln?
H-1.Charcoal burners were a strange breed, living a
lonely life in the forest, like wild beasts… At its best,
making charcoal was not for any normal human. The
time required for charring a small mound varied from
one to two weeks, but with mounds 30 feet or more
round, a month was average. During all that time,
through every kind of weather, the charcoal maker lived
with his mound, sleeping only in dozes for fear a flame
might start and explode into a full fire which would
demolish the mound. There was no time for washing;
there was seldom more shelter than a bark lean-to.

Earth Kiln – Ohio - 1942

Tropical Products Institute
- Mark V

Tropical Products Institute
- Mark V – IN ACTION

Google: 1G Toucan
Figure 4: Completed TLUD

Figure 7: Half way through burn

Figure 10: 1G Toucan Biochar

Larger than TLUDs, appropriate for
home gardeners and consuming small
amounts of scrap wood or “forestry
slash” are:
• Two Barrel Retorts
• Double Barrel Twin Keg Retorts
• Jack Daniel’s Rickyard Technology

Google:
Jolly
Roger
Ovens or
JRO Biochar

Commercial operations require larger
equipment and regulatory approval:
• Adam-style Retorts
• This is a developmental “Chicken or
the Egg” – Nobody makes them
because nobody wanted them

The Mobile Adam Retort c/o New England Biochar

http://flowfarm.org/biochar.html

Make Biochar,
and save your world

Unique Biochar Phenomena
Hugh McLaughlin, PhD, PE
www.acfox.com
November 23, 2014 @ Tufts