Hemp’s role in reducing our dependence on plastic

Hemp has thousands of insutrial uses

Industrial hemp is part of the answer to the proliferation of plastic. The shame of it is that plastic is a truly useful and essential material but we have abused it unforgivably, and that behaviour shows no signs of abating any time soon. Half of the plastic we produce is designed for single usage only and less than 10% of the remainder is recycled.

A quick primer on plastic

The word “plastic” comes from the Greek words “plastikos” and “plastos” meaning pliable and capable of being shaped. Plastics are composed of chains of very long and complex molecules called polymers. In nature, cellulose is a common polymer that makes up the cell walls of plants.

Plastics depend on cellulose for their flexibility and toughness. The most common source of cellulose for industrial manufacturing purposes is the carbon in petrochemicals and other fossil fuels. But when the first synthetic polymer was invented 150 years ago (celluloid, as a substitute for ivory in billiard balls), it was made from cellulose extracted from cotton fibres, which can contain 90% cellulose.

When the method for creating plastic from oil was discovered, oil was incredibly cheap and supplies seemed endless. So it became a prime source. Check out this short article that describes the process for converting petroleum to plastic. World War II accelerated the science and the manufacturing technology, and the post-war boom generated massive demand for this cheap and useful material.

Why hemp can partly replace plastic – but not totally

It can take 500 to 1,000 years for a plastic drinks bottle to biodegrade. Natural polymers degrade far more rapidly, so plastics made from these materials are a critical component in saving the planet from drowning in plastic and similar packaging materials.

Naturally-occurring cellulose can be extracted from a wide range of renewable and sustainable biomass materials – straw, softwood trees, rice husks, cotton waste and so on – to create cellulose film (Cellophane) and other replacement materials. These products are called bioplastics.

Hemp is the outstanding plant candidate as it contains about 70% cellulose, is easy to grow,  and has a vast range of other uses too. It is used for building materials, clothing textiles and paper amongst thousands of applications. Hemp seed oil is used in cosmetics manufacturing.

Composite bioplastics made from a blend of hemp and other plant sources feature high strength and rigidity and can already be found in boats and cars.

However, mainly due to anti-marijuana laws in the 1930s USA that were not repealed until 2018, hemp production and research was severely stunted. It is now 50 years behind where it should be and is far from quickly becoming a commercial alternative to plastic.

Also, the acreage of hemp required to fully replace chemical plastic would be enormous and possibly impractical. But that is not the objective.

So why can’t we grow more hemp in the UK? The glitch in the law.

It all hangs around hemp’s first cousin, marijuana, and the miniscule level of the psychoactive substance THC and other cannabinoids contained in hemp flowers and leaves. Hemp growing is permitted under license here in the UK but the flowers and leaves must be destroyed on the farm because, once removed from the hemp plant, they are considered a Controlled Substance.

Valuable cannabidiol (CBD oil) is the most lucrative by-product of hemp farming and hemp produces high yields but comes under UK legislation on Controlled Substances. The glitch in the law is that, while it is legal to produce and sell CBD products in the UK, it is illegal to extract it from plants, including industrial hemp.

That greatly reduces hemp’s attractiveness as a cash crop because only the seeds and stalks can be harvested. The CBD industry is booming in the UK but we are forbidden to extract it from hemp.

Hemp has been grown in this country for hundreds of years and was recognised as a vital raw material (the builders of the pyramids in Egypt used hemp ropes). In fact, Elizabeth I made it mandatory for farmers to set aside one acre in 60 for hemp. Henry VIII made farmers reserve a quarter acre of their land for growing it or face hefty fines.

How is industrial hemp different from cannabis plants?

Industrial hemp is any variety of the Cannabis sativa plant species that contains less than .3% THC. By comparison, cannabis plants yield about 15% or more THC. Hemp derivatives are not use in any narcotics.

Along with bamboo, hemp is one of the fastest growing plants in the world. It also absorbs more CO2 than any trees or other crops and growing it does not require any agrochemicals.

Is it easy to grow hemp in the UK?

Yes, hemp is relatively simple crop to cultivate. It needs no special attention, minimal watering, and no herbicides or pesticides. It is a hardy plant, thriving in most soil types and the UK’s temperate climate.

Currently there are only about 20 licensed growers and just 5,000 acres (2,000 hectares) under hemp cultivation. Licenses are issued by the Home Office costing £580 for 3 seasons and £326 to renew.

The argument for encouraging hemp cultivation

Given that it is excellent at absorbing CO2, has a multitude of industrial uses, and can go some way to reducing our dependence on plastic, it would seem logical to encourage growers.

Current licensing conditions make it impractical for anyone other than commercial growers and that could easily be changed. It grows anywhere, and allotments, waste ground or back gardens could produce it.

Removing the ban on extracting CBD oil from hemp is the pivot for riving this forward. We cannot see any negative and hope the pressure on the government to change the legislation has the desired effect, and quickly.


Further reading: Potential benefits of hemp for UK farming