Hemp Carbon Capture

The image on the left is of Al Gore showing a graph of organic agricultural land by region. The part of the chart in yellow shows that Oceania has half of the world’s certified organic farmland. This is a great opportunity for Australia to lead the world in carbon sequestration using organic farmland.

Hemp captures carbon from the air and stores it in biomass and in the soil. The majority of the carbon is retained in the woody parts of the stem known as hurd. One hectare of industrial hemp can absorb up to 22 tonnes of CO2 per hectare. A study carried out at Cambridge University delivered results ranging from 8 to 15 tonnes per hectare for UK crops. In parts of Australia It is possible to grow to 2 crops per year so absorption is doubled.

Hemp’s rapid growth (grows to 4 metres in 90-120 days) makes it one of the fastest CO2-to-biomass conversion tools available, more efficient than agro-forestry. Biomass is produced by the photosynthetic conversion of atmospheric carbon. The carbon uptake of hemp can be accurately validated by calculations derived from dry weight yield. Highly accurate figures for total biomass yield and carbon uptake can then be made, giving a level of certainty not available through any other natural carbon absorption process. The following carbon uptake estimates are calculated by the examining the carbon content of the molecules that make up the fibres of the hemp stem. Industrial hemp stem consists primarily of Cellulose, Hemicellulose and Lignin,

Cellulose is 70% of stem dry weight. Cellulose is a homogeneous linear polymer constructed of repeating glucose units. The carbon content of cellulose accounts for 45% of its molecular mass.
Hemicellulose is 22% of stem dry weight. Hemicellulose provides a linkage between cellulose & lignin. It has a branched structure consisting of various pentose sugars.
Lignin is 6% of stem dry weight. Lignin is a strengthening material usually located between the cellulose microfibrils. The lignin molecule has a complex structure that is variable

To summarise the above, one tonne of harvested stem contains:

0.7 tonnes of cellulose (45% Carbon) ·
0.22 tonnes of hemicellulose (48% Carbon)
0.06 tonnes of lignin (40% Carbon)

The figures above are from a paper written by James Vosper in 2011. A full copy of a paper- Draft Methodology for Broadacre Industrial Hemp Planting– can be accessed at:-

http://hempalliance.org.au/wp-content/uploads/2017/05/Industrial-Hemp-as-Carbon-Farming.pdf

For the purposes of estimation, we use an average figure of 10T/ha of CO2 absorption, a figure we hold to be a reasonably conservative estimate. This is used to predict carbon yields, but CO2 offsets are be based on dry weight yields as measured on farm.