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Hemp Versus Flax in Bioplastic Production

Updated: Jul 8

Hemp versus flax in bioplastic production

Let’s start from somewhere we all agree on. Plastic is bad — we all know that. It sticks around for ages, and processing it properly is too expensive to be wide-scale.

Also, the actual manufacturing process, from sourcing the oil to molding the product, is also very polluting.

Fortunately, the answer may be on the horizon.

Traditional, “normal” plastic is made from petroleum, which is a fossil fuel.

However, researchers have figured out how to make plastic from plants.

These plant-based plastics are known as “bioplastics”, and can come from many different plants. The most common bioplastic plants right now are corn and sugarcane. However, two new plants are showing a lot of promise: hemp and flax.

If you don’t know what flax is, it is the plant used to make linen.

But out of the two, there isn’t much research on either (yet). So which one would be better or more usable for bioplastic production? Let’s find out.

Table of Contents:

Through the course of this article, you will learn the following things.

How are bioplastics made?

The hemp versus flax debate: which is better for making bioplastic?

  • Round 1: Accounting for carbon and water

  • Round 2: Accounting for fertilizers and nitrogen

  • Round 3: Accounting for harvesting and biomass

  • Round 4: Accounting for phytoremediation and by-products

  • Bioplastics vs. biodegradable plastics

  • The verdict

And now, without any further ado, let us get right into it.

How are bioplastics made?

Really quickly, here is the process of making a bioplastic. It’s important that you understand it, and what each of the key terms are.

  1. First, you pick a “feeder plant”. These need to be plants that are high in cellulose or starch. You grow the plants in good conditions, with the right amount of sunlight, water, and nutrients.

  1. Then, you harvest the plants. The harvested product is processed, and the starch/ cellulose extracted (we use this to make the plastic). The remaining organic material can be used for other things.

  1. Once the harvested plants have been processed, the cellulose/ starch is converted to glucose. This process is called hydrolysis.

  1. After the hydrolysis, the glucose is fermented, forming lactic and other organic types of acid. Then, the acid undergoes a process called “polymerization”. This turns the acid into PLA (polylactic acid). This is a type of bioplastic.

  1. Then, all that’s left to do is form the PLA into pellets, and use them to mold stuff out of.

Please also note the difference between two related terms: biomass and feedstock. When you plant seeds into the ground, they are called biomass.

They continue to be called biomass till you harvest them.

After harvesting, when you extract the cellulose/ starch, these are renamed to “feedstock”.

When the feedstock turns into PLA, it is called a bioplastic. Now let’s move on to the hemp vs. flax bioplastic production debate.

Hemp vs. flax bioplastic production

I have identified four key points or “factors”. Each of them directly affects the suitability of hemp and flax as a bioplastic source.

And it’s not just about the making of the bioplastic source either. I’ve also taken into consideration points that other people have missed, such as the ones below.

●     The environmental impact of growing the plant to begin with.

●     How much usable material we get out of each plant, per hectare.

●     The amount of water that is used and carbon emitted/ absorbed.

●     If one plant is better than the other (in terms of biodegradability).

With that out of the way, let’s get into factor number one that affects hemp vs. flax bioplastic production.

Round 1: Accounting for carbon and water

Beginning with the carbon aspect. Fields of hemp and flax absorb a lot of carbon from the atmosphere. In ESG sector jargon, this process is called “sequestration”.

The difference lies in how much each plant can absorb. For flax plants, one hectare can absorb up to 3.7 tonnes of CO2 from the atmosphere.

That’s amazing right? It is quite impressive, until you look at hemp plants.

One hectare of hemp can absorb up to 22 tonnes of carbon from the atmosphere. And while I haven’t been able to find any (academically verified) data on flax, I can confirm that hemp plastics need 45% less energy to manufacture.

Coming to the water use. It’s quite clear-cut really. Hemp plants need only 3 ML of water to grow for each hectare, each growing cycle.

One hectare of flax plants needs 4 ML of water, and that’s in addition to several fertilizers. And by the way, ML here stands for “MegaLiters”, where 1 ML = 1,000,000 liters”.

Round 2: Accounting for nitrogen

There are two kinds of plants in this world — ones that use nitrogen and ones that restore it.

Flax is the former, hemp is the latter.

This is a big point in terms of hemp vs. flax bioplastic production.

Studies have shown that hemp plants can restore 100 kg of nitrogen to the soil, per hectare.

So you see, hemp plants produce a lot more usable biomass with less water, less carbon, and without sapping too much nitrogen from the soil. In fact, flax plants use up so much nitrogen that they are usually planted only once per six years in a field.

That’s right — you can only plant flax in one area once every six years. And that leads us nicely into my next point — the growing seasons.

Round 3: Accounting for biomass

First, let me talk about the growing season, or biomass. Like I said earlier, flax can only be grown every six years in the same field.

The nitrogen is a big reason, but there are others as well. Long story short, flax fields need a lot more crop rotation. Hemp can also benefit from crop rotation, but it doesnt need to be rotated.

Additionally, hemp has a very quick growing cycle.

The entire initial planting to harvesting time can be as little as 100-120 days. This means that hemp plants can be planted twice a year — double that of other biomass sources. That’s another big point to the cannabis plant in the hemp vs. flax bioplastic production fight. Coming to the biomass side of things, hemp plants win again.

For every hectare of hemp that you plant, you get 10 to 15 tonnes of usable biomass.

Out of that, 7 tonnes (almost) is from hemp fiber alone. Contrast that with flax, where you get 2 tons of usable biomass. Also, you can only plant flax in May, according to the Canadian government. 

That is the only viable period when your crop will survive. And additionally, hemp plants come with by-products other than feedstock as well. Let’s talk about those.

Round 4: Accounting for phytoremediation and by-products

About the by-products–a hemp plant can give you a lot more usable product per hectare, you’ve seen that. But hemp can also give you other products as well, from the same field.

Here are just some of the by-products of using hemp plants as a bioplastic source.

  1. From Seeds: Hemp oil, hemp protein.

  1. From Hurds: Hempcrete, animal bedding, mulch.

  1. From Fibers: Textiles, paper, bio-composites.

  1. From leftover Biomass: Biofuel like ethanol, biomass pellets.

  1. From Leaves and Stems: Compost, animal feed.

Now, I’ll be the first to admit that flax plants also leave you with a lot of the same by-products. You get flax fibers, flax hurds, flaxseed oil, etc.

However, remember the point I made right before this one.

Hemp plants give you 13 tonnes or 550% more usable biomass per hectare than flax plants.

And hemp plants can be grown and processed twice per year, so in reality you get 1100% more usable product from hemp plants. Now you know how bioplastics are made, and how the hemp vs. flax bioplastic production debate works.

Also, I have seen people use the term “bioplastic” as a substitute for “biodegradable plastic”. This is flat-out wrong — they are two different things.

Bioplastics vs. biodegradable plastics

Bioplastics are made from glucose that comes from plant cellulose or starch They reduce the need for fossil fuels. This helps the environment. But, not all bioplastics break down quickly.

Biodegradable plastics can come from natural or fossil fuels. They break down faster than regular plastics. This happens when exposed to bacteria, light, or heat. But, biodegradable plastics need specific conditions to break down.

Key Points:

●     Bioplastics: Made from natural materials.

●     Biodegradable plastics: Break down faster, need special conditions.

Both types help reduce plastic waste. You need to know how they work and where they break down. This helps make better choices for the environment.

Both hemp bioplastics and flax bioplastics are not biodegradable plastics, but actual bioplastics. Don’t get confused.

The verdict

In conclusion, I’d just like to point out that both hemp and flax are very good crops to plant. They are not as taxing on the environment as cotton and other cash crops.

The products that they produce are all used, with no wastage.

The finished products that they are raw material for are mostly biodegradable. There is a lot of ongoing research into these plants as well. However, when you stack up all the points and look at hemp vs. flax bioplastic production objectively, there is a clear winner.

Hemp bioplastics have less of an environmental impact, the process of making them is cleaner, and they can be made faster.

This makes them far superior to flax bioplastics, and any other organic bioplastics for that matter. And with that, we come to the end of this article on hemp vs. flax bioplastic production.

I hope you found it useful, and I’ll see you in the next one.


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