notes on

The atomic weight of carbon is 12 atomic mass units,
while the weight of carbon dioxide is 44,
because it includes two oxygen atoms that each weigh 16. 
So, to switch from one to the other, use the formula:
One ton of carbon equals 44/12 = 11/3 = 3.67 tons of CO2.

Dry Matter Productivity (DMP) represents the overall growth rate or dry biomass increase of the vegetation, expressed in kilograms of dry matter per hectare per day (kgDM/ha/day). It is directly related to ecosystem Net Primary Production (NPP), expressed in gC/m2/day. Similarly, the Gross Dry Matter Productivity (GDMP) is directly related to the Gross Primary Production (GPP).

The main difference between DMP/NPP and GDMP/GPP is the inclusion of the autotrophic respiration of the vegetation.

To have the total value of NPP, i.e. including the roots of the trees, we have to multiply by 2 because below ground carbon biomass is, on average, equivalent to carbon allocated aboveground.

3 tons of carbon fixes 11 tons of carbon dioxide.

KW Email Jan 24

If a heat stove is the next level, then one household can make a couple of gallons of biochar a day in the winter if they continually load up a 1 gallon paint can retort with wood chunks and place it in the woodstove like a log.

Each paint can will yield about 1/3 of a gallon of biochar, so 6 loads will give you 2 gallons.
It will take 100 days to make 200 gallons, which is about one cubic yard. which is ~240 lbs.

If the household is making biochar for use in the garden, composting, tree-planting, etc then they will want a dedicated kiln like the Ring of Fire Kiln. One Ring of Fire can make 3 cubic yards of biochar in 4-5 hours of burn time.
This is about 700 pounds of biochar.
We can accurately estimate the carbon sequestration CO2 removal impact of each batch using a protocol we are developing, but using our standard assumptions for carbon content and bulk density of the biochar, we can confidently say that multiplying the mass by 2x gives a conservative number for the carbon sequestered.

So, 700 pounds of biochar times 2 = 1400 pounds of CO2 or .7 tons of CO2 removal.
In metric tonnes (how CO2 is usually measured) that would be .6 metric tonnes of CO2.
If a household makes 30 batches of biochar a year, they could sequester 19 metric tons of CO2 per year.
That is equal to the current CO2 emissions of one high-resource consuming American.

Here is a number for dry bulk density of
biochar made from softwoods is about 230 pounds per cubic yard. 
Biochar made from hardwoods is about 250 pounds per cubic yard.
To estimate CO2 removal for any amount of biochar, measure and report the volume in cubic yards.
Multiply by dry bulk density to get pounds.
Convert to metric tonnes and multiply by 2 to get tonnes of CO2 removed from the atmosphere


20 t/ha would yield 4 to 5 tons of biochar with a potential to remove ~10 to 12.5 metric tons CO2e. 
20 ton per hectare of dry biomass would yield 4 - 5 tons of biochar with a potential to remove 10 - 12.5 metric tons of CO2e.

When you subtract the fossil fuel inputs for harvesting and handling, power if used, transportation of the biochar to use and the average temperature in the soil where it is applied, the carbon dioxide removal potential would be between 2 - 2.5  metric tonnes CO2e @ metric ton biochar.

At 4 metric tons @ hectare x 2.5 metric tons CO2e @ metric ton biochar
you would sequester 10 metric tons CO2e @ hectare @ year.
At that rate you would need to harvest residues from 100 hectares @ 2000 dry metric tons wood @ 1000 metric tons CO2e.

At one metric ton of biochar per year and 2.5 metric ton CO2e per metric ton of biochar you would need 400 homesteads to sequester 1000 metric ton CO2e.

Each homestead would sequester 2.5 mt of CO2e requiring 1 metric ton of biochar.

The EU target is 2.5 mtCO2e @ capita,
 equal to one metric ton biochar per year.
In developing countries, the average city dweller emits 1.49 metric ton CO2e per year
while rural inhabitants emit 0.8 mt CO2e/year.  

The 2017 Global Carbon Emission target was 2.5 - 3.3 mt CO2e per person per year by 2030.
The average global emission is about 3.4 mtCO2e/person per year.    

The European average is about 8.2mt CO2e/capita
which would require 3.28 mt biochar
from about 16 mt of biomass.
The range is 4 - 43 mtCO2e/capita.
EU household carbon footprints range from 4.6 - 54.9 mtCO2e @year.  
According to one study US households emit from 17.7 - 20.6 mt CO2 per person per year.
At 2.5 mt CO2e/mt biochar they would have to produce 7.1 - 8.25 mt of biochar from about 35 - 42 mt of dry biomass residues per person per year.

Someone on the list reported rural smallholders producing about 500 kg/biochar/.5mt per year (Biochar Life?). The stove production in Vietnam that Joseph reported at 300g per meal would add up to about 330 kg/.33 mt year which would be roughly equal to their carbon footprint.

The pit kilns, TLUDS and top lit piles that Kevin McLean has been working with might approach one mt per year.

We need to deal with large scale carbon dioxide removal (CDR). Biochar is clearly part of the solution. Rural populations could probably remove as much CO2e as they emit. However, urbanization has been the major trend in world populations.


How to convert the total biomass to units of carbon per area?

Biomass is typically measured in metric tons of dry mass of biomass per area, usually per hectare.
To convert total biomass to units of carbon per area, divide the total biomass by the mass fraction of carbon in the biomass.

The mass fraction of carbon in biomass varies depending on the type and source of the biomass,
but it is typically around 0.45 to 0.50.

For example, if the total biomass is 5 metric tons per hectare, the amount of carbon per hectare would be 5 / 0.45 = 11 metric tons of carbon per hectare.

NPP = Net Primary Production
50% of dry weight of biomass created is C (Carbon)
Heterotrophic Respiration. Around 20% of C is loss through dead biomass decomposition.
NEP = Net Ecosystem Production. 1 ton of C corresponds to 3.667 tons of CO2.


To convert above ground biomass and carbon to tonnes per hectare, you will need to follow these steps:
  • Convert the biomass measurements to carbon using appropriate conversion factors. Different vegetation types have different carbon contents, so you need to consult relevant scientific literature or local studies to determine the appropriate conversion factor for your area. For example, a common conversion factor for forests is to assume that biomass is 50% carbon.
  • Multiply the carbon content by the area of your land in hectares. If you have measured the area, simply multiply the carbon content by the area. If you have measured the area in a different unit (e.g., square meters), convert it to hectares by dividing by 10,000.
  • Express the result in tonnes. The result of step 3 will be in terms of carbon per hectare. To convert this to tonnes per hectare, divide the value by 10, as there are 10 tonnes of carbon in one tonne.
How Applied Science Can Benefit Smallholder Farmers - with Dr. David Hughes
Biochar Offset
Life Cycle Assessments of Biochar Systems
Biochar: A Viable Option for Smallholders in the SubiHumid Tropics