Industrial hemp has been scientifically proven to absorb more CO2 per hectare during its growth cycle than any forest or commercial crop.
This means that the production of Hemp is carbon negative. It absorbs more carbon from the atmosphere during its growth than is emitted by the equipment used to harvest, process and transport it.
In addition, the CO2 is permanently bonded within hemp fibres that can go on to be used for anything from textiles to paper to building material (it is currently being used by BMW in Germany to replace plastics in car construction.)
As an alternative to what can be grown or sourced from oil, and given that it can be constantly replanted, it meets the permanence criteria as defined by the Kyoto Protocol.
So, what’s the science behind carbon capture?
One hectare of industrial hemp can absorb 22 tonnes of CO2. Where two crops per year are grown, absorption is doubled. And hemp's rapid growth (up to 4 metres in 100 days) makes it one of the fastest CO2-to-biomass conversion tools available. Even more efficient than agro-forestry.
Biomass is produced by the photosynthetic conversion of atmospheric carbon, and 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 probably always is variable
So 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 roots and leaf mulch (not including the hard to measure fibrous root material) left in situ, represent approximately 20% of the mass of the harvested material in initial field trials. The resulting carbon content absorbed but remaining in the soil, will therefore be approximately 0.084 tonnes per tonne of harvested material.
According to Defra, UK Farming emits a total CO2 equivalent of 57 million tonnes of greenhouse gases. UK agricultural land use is 18.5 million hectares. This amounts to an average of around 3.1 tonnes of CO2 per hectare total embodied emissions. As a low fertiliser and zero pesticide/herbicide crop, with little management input, the carbon emissions of hemp cultivation is well below the average. Therefore we can assume the matter remaining in soils roughly offsets the cultivation and management emissions.
Furthermore, these figures do not include the additional carbon dioxide that is saved by substituting unsustainable raw materials with hemp for products such as building materials, plastics, cosmetics, composite boards and insulation materials. According to Limetechnology Ltd, Hemcrete locks up around 110kg of CO2 per m3 of wall, compared to the 200kg of CO2 emitted by standard concrete. It also excludes the carbon savings of replacing tree-derived products and leaving trees to continue to absorb CO2.
The science is clear. The cultivation of industrial hemp in the UK is vital in our battle to reduce carbon, reduce pollution, conserve water and improve soil quality. Join us in making things better.
NB the information above is quoted in most part from James Vosper's study, FRGS Company: GoodEarth Resources PTY Ltd (ABN 79 124 022 859). Our thanks.