Cannabis: The greatest sequestration agent of them all.
A Field of Marijuana. Photo ©Bart Pogoda and used with permission.
I lived in Amsterdam for some years and got to know many cannabis growers. These farmers, mostly based in Switzerland, do not grow “industrial” (ie low THC) hemp, but they do grow cannabis in industrial quantities. I do tend to use the terms marijuana and hemp interchangeably because I regard the mutant “low THC” version of the plant as an abomination. I understand however why groups like the North American Industrial Hemp Council go to such lengths to differentiate between industrial hemp and natural marijuana. They operate in a climate of terror and ignorance.
In reality the main difference is the fact that low THC hemp is grown much more densely than high THC weed. The higher the planting density the lower the THC. Yes there has been some selective breeding to reinforce that, and in some cases even some genetic engineering (a nightmare), but on the whole it is the same plant. You can’t get high smoking low THC weed, but keep in mind that not all weed grown on an industrial scale is low THC as there is a massive market for the real thing in both legitimate retail outlets like the Dutch coffee shops, and of course as a part of the illegal trade that makes up around 20% of the world’s economy.
I have seen with my own eyes fields of what I would term “medicinal” weed being harvested. Crews of people pick it by hand and then sit around large tables “nipping”, removing the choicest buds and trimming them back for transport and sale in Holland (and smuggling into the UK and other parts of Europe). The stalk, and usually the leaf and tip too, are incinerated, releasing that trapped carbon directly back into the air. This is a crying shame as that’s where some 90% of the carbon in the plant resides. I am very keen to change this practice such that instead of burning off these leftovers they put them to some industrial use. As a bonus they should be eligible to create JI or ETS carbon credits from the change in farming practice.
A field of medicinal weed will sequester around 22 tonnes of carbon dioxide per hectare. A typical crop is grown on 100+ hectare lots in Europe (mostly Switzerland and Hungary), and, using crop rotation to keep the soil nice and fertile you can get two decent dope crops per year (interspersed with some leguminous crop like peas, or companion planted with basil or similar), so that’s a sequestration rate of around 5000 tonnes per year. With credits priced at around €15 - €25 per tonne this represents an additional income to the farmer of around €75,000 - €125,000. There are thousands of such farmers in Europe alone, meaning there is the potential for sequestration of millions of tonnes of CO2. But only if the carbon is stored in some product that is never likely to release the carbon again.
Enter Hemcrete®. Made from lime and hemp this building material has been in use for many thousands of years. The Romans used to build with it; it’s light, strong and fire-retardant. Given also that concrete production accounts for some 5% of the world’s carbon emissions it is high time (pardon the pun) something was done about that.
In the UK, the construction and use of buildings accounts for over 50% of the carbon dioxide produced. Studies have shown that up to 200kg of CO2 is emitted in the production of each square metre of walling for houses alone – equating to 40 tonnes for the walls of a typical house.
To significantly reduce this figure, Lime Technology has launched Tradical® Hemcrete®, a new product innovation of cast in situ hemp-lime walling.
Created in partnership with Lhoist UK Castle Cement and Hemcore, three of the world’s leading authorities on lime and hemp based products, Tradical® Hemcrete®, often generically known as Hempcrete, can actually reverse the damaging effects of greenhouse gases by locking up harmful CO2 emissions within wall construction.
It comprises a unique blend of specially prepared hemp shiv (Tradical® HF) and a special lime based binder (Tradical® HB); which together form a bio-composite building material. The hemp, which forms the key element in these products, is grown and havested in the UK, as illustrated.
Helping to reverse the damaging effects of greenhouse gases, Tradical® Hemcrete® locks up around 110kg of CO2 per m³ of wall and provides one of the best value materials for low impact, sustainable and commercially viable construction.
Produced mainly from renewable sources, Tradical® Hemcrete® is mixed on site for fast track construction and delivers high levels of insulation, airtightness and vapour permeability. It is spray applied on site using a shuttering system to create the walls.
The generic term for this ages-old building material is “hempcrete” and Hemcrete® is a branded version of it made by a company in the UK called Lime Technology but it’s basically the same stuff. As the website Construction Technolgies points out:
Hemp is a premium high strength fiber, similar to flax in many ways, a miniature forest grown in one season. The hemp stalk straight off the field can be incorporated into building materials because it has strength and engineering properties as does any cellulose stalk, but hemp has greater size and strength than many plants for its weight, growing period, and for our region. In the case of cellulose fiber having sufficient strength, bamboo has successfully been used as reinforcing rod in concrete instead of steel. Hemp fiber added to concrete increases tensile and compressive strengths, reduces shrinkage and cracking. Hemp processed with a hammer mill can be added to minerals in the class of Earth Cellulose building materials which is most easy to process. Earth cellulose material is suitable for use on farms and for urban projects. The material when incorporated in the proper design can be handled much like concrete at one third to one half the density of concrete. Batch plant trucks available now can drive to the site and mix the material for placement in form works, also available on a truck.
So Europe’s marijuana growers could be creating large volumes of high quality building materials for retail sale, further boosting their revenues, and capturing carbon in sufficient quantities to generate viable carbon credits. The hemp stalks can also be used to create bio-fuels but this negates any credits you’d be able to generate from the change in farming practices as the fuel would simply get burned again. You could generate a small volume of credits in the form of fuel switching credits but nowhere near the volume as you would from concrete replacement. Contact Carbon Planet’s carbon origination team if you are in a position to take advantage of this. — DS
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