The Life Cycle of Tencel
Recently, we decided to use Tencel in our new clothing line. We did it because the voices on the internet told us that “Tencel is a sustainable fiber...” and we believed them. We received results from brands, bloggers, journalist, influencers and anyone in-between presenting facts and figures about the sustainability of the fiber. However, what we didn’t see, were sources to facts or figures of any reputable source. So we decided to create this page. The goal was simple - be helpful. Be helpful to anyone that wants dig a little deeper and provide sources to all data, and in many cases original sources. We wanted to discuss the good, the bad and the unknown. Most importantly, we didn’t want to be afraid of showing all the facts. Hopefully we did that.
We created a short and long version. The short is just what you see as you scroll the page. The long version is accessible by clicking on the images and text. The long version is where you will see the full story and links to learn more.
Just A Quick History
Lyocell Inputs
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Wood
While the common conception is that all lyocell/Tencel is derived from eucalyptus trees, that is not accurate. Lenzing specifically, reports five species of trees in which they or their partners harvest from for Tencel production. They include, eucalyptus, beech, pine, birch and spruce. Lenzing does not specify a predominant wood species for Tencel production but they do provide a great breakdown of speicies of wood and regions grown, which you can view below. In our case, we will focus on eucalyptus as it makes up the majority of imported wood. Side note, Lenzing does an amazing job with locally sourced from Central European countries and we would consider the process more environmentally friendly compared to imported wood pulp.
Here are some quick facts about eucalyptus trees in general and eucalyptus trees sourced by Lenzing.
The Good:
- Eucalyptus trees are a renewable resource.
- Eucalyptus trees have a relatively fast growth rate with about 60-70% of its overall height happening in the first 10 years.
- At Lenzing, no artificial irrigation is needed at any stage in the growth process.
- All eucalyptus trees used at Lenzing come from FSC plantations in South Africa.
- Trees grown at Lenzing’s plantation farms are done in regions with “sufficient natural moisture”
- Plantation farms do have the benefit of eliminating deforestation of natural forests.
- To conserve biodiversity, Lenzing claims that 25 percent of the plantations farmland is not grown on.
Need To Manage:
- Even when rainfeed, eucalyptus trees can deplete groundwater resources and cause downstream problems to native ecosystems.
- The United Nations Food and Agriculture Organization found that eucalyptus plantations have a “heavy consumption of soil nutrients” and can inhibit the growth of other plants.
- Small amounts of natural fertilizers are used but since no irrigation occurs, the only environmental impact comes from the small amount of N2O emitted.
Overall, we think eucalyptus trees are a great renewable resource for fiber production with the major concern being water and soil conservation. As for eucalyptus plantations, as long as the company grows the trees in moisture rich regions and workswith environmental agencies to subside inevitable problems to native ecosystems, we find the impact minimal. Lenzing seems to be doing some of this work by teaming up with Canopy - a non-profit fighting to protect forests!
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Pulp Production
Pulp production is pretty straightforward and a dirty process. I will talk about water and energy usage in other sections. I want to focus this section on the bleaching process.
It all starts with elemental chlorine (Cl2). Simple put, elemental chlorine produces carcinogenic compounds and is hazardous to the environment. While it has declined over the years, it still persists in the industry and it might hold anywhere from 5-20% of the global market share. This amazes/frustrates me, as it should be zero!
On the other side of the debate we have ECF (Elemental Chlorine Free) and TCF (Totally Chlorine Free). While the name might be confusing, ECF does contain low doses of chlorine dioxide but is completely free of elemental chlorine. TCF is 100% chlorine free and uses an oxygen based process to bleach the pulp. While some environmentalist tend to side on the chlorine free method (including myself), some research identifies the environmental impact of both ECF and TCF as similar.
In studies done by the European Union, they concluded that, “it is now possible to demonstrate that the discharges to watercourses, from both ECF and TCF, are of no environmental concern”. The ECF process might even use less energy. The study did acknowledge that adsorbable organic halides (AOX), which are bad, were still present in the ECF process even after effluent treatment. However, they noted that the amount of AOX was insignificant. I did not see an examination or discussion of the problems at scale. Toxicity levels were present in both methods but at low levels. My point being, since ECF holds a market share of possibly 94%, compared to TCF which holds roughly a 5% market share, shouldn’t we think about diversifying our bleaching processes (ECF and TCF). This would minimize the effects of AOX exposure to the environment and provide more data. Oh, and we should just ban elemental chlorine outright!
Lastly, Lenzing only uses TCF bleaching in its internal processes. For all sourced imported pulop, ECF bleaching is used. Also, all by-products from Lenzing's internal pulp production process which include acetic acid, furfural, xylitol, magnesium lignosulfonate, soda (sodium carbonate), magnesium lignosulfonate, soda (sodium carbonate) are used in their biorefinery to produce energy for their plants in Czech Republic and Austria.
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NMMO - N-Methylmorpholine Oxide
NMMO is the only chemical solvent used in the production of lyocell. The chemical and the effluent from the production process is considered nontoxic and easily regenerated. As we will see soon, the NMMO solution for making Tencel is 99% recyclable. Of the 1% waste, that waste can be easily treated using biological wastewater treatment methods. The effluent contains “only small amounts of organic chemicals and salt, mainly sodium sulphate”. Overall, the environmental of NMMO are considered low.
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Enzyme Treatment
In 1991, enzymatic treatment was introduced into the lyocell process as a way to stop the filibratation on the yarn. Fibrillation leads to fuzz/pilling on the end fabric. The process is also called biopoliching. Biopolishing also gives a softer and more peach-skin feel to the end fabric. Biopolishing does provide a small loss in tensile strength but overall, it’s negligible as the final fiber has a higher tensile strength compared to other fibers like cotton. Enzymatic treatment is used in food production and is considered safe.
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Heat/Energy
One of the major issues with lyocell production is energy usage. It’s inline with polyester, if not a little higher. Pulp production is specifically energy intensive. However, with plants like Lenzing's, which derived 100% of their energy needs from renewable resources, the effects on the climate start to mitigate.
The best up-to-date research on viscose production comes from Utrecht University in the Netherlands. It looked at the entire Life Cycle Assessment (energy, global warming potential, toxicity, water usage and land usage) of Lenzing’s modal, viscose, and Tencel production and compared it to conventional cotton and polyesters. The study seems pretty relevant however, some technologies have changed since the 2012 publication but I don’t think the results would vary a ton.
I will refer to one Tencel and one Modal used in the study. We will also provide research on Tencel's new Thailand facility.
- Tencel Austria (From Study): Derived from a mixture of eucalyptus and beech wood. Eucalyptus is sourced from plantation farms in South Africa (see wood for more information) and European beech wood. The process uses 70% natural gas and 30% biomass for its energy demands.
- Modal Austria (From Study): Derived from European hardwood that is sourced within the region. The entire production process is done at Lenzing’s Austria plant where energy demands are met by the biorefinery. Almost 100% of the energy needs are derived from renewable resources.
- Tencel Thailand (Not From Study): Derived exactly the same way as Tencel #1 but it will be processed at Lenzing’s new facility in Thailand. All energy demands will come from the biorefinery, similar to Modal Austria. The majority of the biorefinery inputs will come from black liquor or bark from pulp production and municipal solid waste incineration (MSWI).
Quick Asterisk:
The study did not look at the Tencel Thailand’s energy profile, as the plant was not built at the time of the study. However, I believe we can take the conclusions of Modal Lenzing’s energy profile and apply them to Tencel Thailand with one small change - Tencel Thailand will use a lot less caustic soda compared to Modal Austria. Refer to Tencel Austria’s caustic uses in the study.
Results:
- Theoretically, Tencel Thailand will have the lowest overall energy profile compared to all regenerated fabrics, cotton and polyester. The amount of energy needed is still quite high however, the use of renewable resources and incineration of by-products derived from the production process benefit it tremendously.
- All three regenerated fibers use less non-renewable energy compared to polyester while Modal Austria and Tencel Thailand use less non-renewable energy compared to cotton.
I would note that if this study was redone today, I am 100% sure all Lenzing fibers will have a better energy profile compared to the study, as Lenzing has become even more energy efficient.
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Water
I am not going to analyze the full water footprint associated with Tencel but I do want to provide some broad facts.
- Total water usage for Tencel production has been reported at around 100 m3/t (Lenzing) to 263 m3/t (Utrecht University). Even at that higher amount, Tencel production uses less water compared to conventional cotton production.
- Lenzing claims Tencel production uses about a third less water compared to viscose and the Utrecht study found that the overall water usage to be about a 40% difference from viscose to Tencel - 445 m3/t and 263 m3/t respectively. Whatever the case, it seems to be less.
- The non-profit Water Footprint found that Tencel has a lower total water footprint compared to viscose. A lot of this has to do with the reuse of the NMMO solution and non-toxicity of the effluent.
- In regards to water footprint, Tencel has a comparatively low impact to all regenerated cellulose fibers in the Utrecht study and a significantly lower impact compared to cotton. Tencel’s biggest impact comes from pulp production with the growing of trees being a slight factor as well.
I want to leave it there as I don’t feel it’s appropriate to compare these stats to polyesters as there are so many variables. A common consensus is that lyocell has a lower impact on water footprint as fossil fuels and end of life play huge factor in polyesters total water footprint. However, the data is just not present.
Making of Tencel
Wood
Most of the wood used in Lenzing’s Tencel production is derived from eucalyptus (South Africa), beech (Europe), pine (USA), birch (Europe) and spruce (Europe) trees. All wood is sourced from FSC or PEFC certified forests/semi-forests/plantations.
Wood is a fantastic renewable resource that Lenzing also uses to fuel their Austria and Czech Republic plants. If sourced correctly, minimal environmental concerns exist. The major concerns would be the effects of groundwater usage and depletion of soil nutrients on natural ecosystems.

Wood Chipping
Once cut, the logs are transported to a wood chipping facility and chopped into small pieces. These pieces are then transported to a pulp facility for further processing. Some pulp facilities will have the wood chipping process done on-site.

Pulp Production
The wood chips are placed in a solution of water, caustic soda (using mercury free technology) and sodium sulfide. An elemental chlorine free (ECF) or totally chlorine free (TCF) bleaching process is used. Both are considered to have a low environmental impact. One of the biggest environmental concerns with pulp production is the energy demand. Lenzing overcomes this by having their own pulp production facilities that use 100% renewable energy. However, only about 50% of all pulp comes from Lenzing facilities while the other 50% is imported. We would consider pulp production the biggest concern from an environmental standpoint.

NMMO Solution
This is where the magic happens. A little science (NMMO) turns the wood pulp into a regenerated cellulose fiber called lyocell. NMMO is the only chemical solvent needed and the compound itself, and effluent are considered to be non-toxic. The best part about the NMMO solution is that 99% of it can be recycled and used again!
Spinneret
The solution is pushed through small holes and the fiber starts to form on the other side.

One Last Spray
It's first treated with a diluted NMMO solution and then demineralized water. This helps strengthen the fiber.

Enzyme Treatment
To help with pilling and fuzz, a simple enzyme treatment is used. This gives the end fabric a softer and more peach-skin feel.

Finishing Touch
The fibers dried and then spun into yarn or thread for final production. They can be spun with other materials as well.

Wood
Most of the wood used in Lenzing’s Tencel production is derived from eucalyptus (South Africa), beech (Europe), pine (USA), birch (Europe) and spruce (Europe) trees. All wood is sourced from FSC or PEFC certified forests/semi-forests/plantations.
Wood is a fantastic renewable resource that Lenzing also uses to fuel their Austria and Czech Republic plants. If sourced correctly, minimal environmental concerns exist. The major concerns would be the effects of groundwater usage and depletion of soil nutrients on natural ecosystems.

Wood Chipping
Once cut, the logs are transported to a wood chipping facility and chopped into small pieces. These pieces are then transported to a pulp facility for further processing. Some pulp facilities will have the wood chipping process done on-site.

Pulp Production
The wood chips are placed in a solution of water, caustic soda (using mercury free technology) and sodium sulfide. An elemental chlorine free (ECF) or totally chlorine free (TCF) bleaching process is used. Both are considered to have a low environmental impact. One of the biggest environmental concerns with pulp production is the energy demand. Lenzing overcomes this by having their own pulp production facilities that use 100% renewable energy. However, only about 50% of all pulp comes from Lenzing facilities while the other 50% is externally sourced. I would consider pulp production the biggest concern from an environmental standpoint.

NMMO Solution
This is where the magic happens. A little science (NMMO) turns the wood pulp into a regenerated cellulose fiber called lyocell. NMMO is the only chemical solvent needed and the compound itself, and effluent are considered to be non-toxic. The best part about the NMMO solution is that 99% of it can be recycled and used again!
Spinneret
The solution is pushed through small holes and the fiber starts to form on the other side.

One Last Spray
It's first treated with a diluted NMMO solution and then demineralized water. This helps strengthen the fiber.

Enzyme Treatment
To help with pilling and fuzz, a simple enzyme treatment is used. This gives the end fabric a softer and more peach-skin feel.

Finishing Touch
The fibers dried and then spun into yarn or thread for final production. They can be spun with other materials as well.

Biodegradability
of Lyocell
Keeping this short and simple - Yes, Tencel is 100% biodegradable/compostable. The image below demonstrates lyocell's biodegradability in surface soil over 16 weeks.

Biodegradable
Keeping this short and simple - Yes, Tencel is 100% biodegradable/compostable. The fiber has a highly crystalline structure which means two things for us: it’s strong and does not biodegrade easily. The highly crystalline structure gives the end fiber an increased tensile strength that is stronger than cotton and other forms of regenerated cellulose fibers. However, having a highly crystalline structure also prevents it from easily biodegrading. While that might sound bad, it’s not. If consumers keep their clothes away from landfills, the high tensile strength of Tencel should give garments/products a long life! And because Tencel will biodegrade, when the fiber ends up in the ground, it will eventually do so! It just takes a little more time.
In surface soil, Tencel takes about 16 weeks to fully biodegrade. Rayon degrades in roughly 3 weeks and cotton in roughly 5½ weeks. If disposed in landfills, the amount of time is impossible to determine. The correct answer is: keep your items out of landfill by keeping them, selling them, donating them or disposing of them in other fashions. A few quick tips - ask the brand if they take back unwanted items, many (including us) do! You can also look for clothing bins!
Environmental
Impact
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Pros
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Cons
Pros
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99% Recyclable The NMMO solution is 99% recyclable which keeps chemicals out of the landfill and aquatic systems.
The Remaining 1% The remaining 1% waste from the NMMO solution is easily broken down using a biological wastewater treatment.
Renewable Resource When done correctly, the sourcing of wood can be a replenishable resource. The logging process at Lenzing is certified by either FSC or PEFC. This prevents deforestation and harmful impacts on local ecosystems.
Less Water Lenzing claims “Lyocell technology only requires one third of the process water needed in viscose technology.” It also uses less than cotton.
Water Footprint No matter the production process, the overall water footprint for Lenzing’s Tencel was found have a lower impact compared to both conventional cotton and polyester. Tencel produced at Lenzing’s state of the art facility provided the best water footprint.
Energy Use Lyocell production is extremely energy intensive. However, Lenzing’s facility is almost entirely run by renewable resources. Specifically, wood pulp.
Less Laundry Lyocell holds anti-bacterial properties which should lead to fewer washes. This can potentially give lyocell huge water and energy savings over its lifecycle.
100% Biodegradable/Compostable Enough said.
Increased Tensile Strength Because of its high crystalline structure, Tencel has a higher tensile strength when dry and wet compared cotton and other regenerated cellulose fibers.
Emission Savings Tencel production provides a greenhouse gas saving of about 1.5-5 times compared to cotton. At best is can save about 15-21 tonnes of CO2 per hectare. -
Needs Water While Tencel does use less water and the overall water footprint is better compared to other fibers, it still uses a good amount of water.
Deforestation While deforestation impacts seem to be minimal in Lenzing's process, it should be worth noting that deforestation can cause major environmental harm. Look for brands/companies doing it right!
Eco-systems Even when done right, the cutting down of trees of any type for mass production will cause disruption to natural ecosystems.
Energy Usage The pulp production process is extremely energy intensive. While Lenzing’s internal facilities are run on almost 100% renewable energy, the 50% of imported pulp are not. This can be improved as renewable energy becomes more widely used.
Land Usage This really depends on the climate and area where trees are grown. If topsoil is preserved, we see the impact as minimal.
Chemicals As with most fiber production, chemicals used during the production process can cause environmental problems. For Tencel, caustic soda and sodium sulfide, which are used in pulp production are of concern. The environmental impact seems to be minimal but precaution to wastewater treatment is a necessity.
Pulp Production As you can see from the other cons, pulp production is energy demanding, uses a lot of water and can be chemically intensive.
Dyeability Because lyocell has less surface energy, it does not take dyes easily. At times, more chemically intensive dyes are needed to dye the fabric. The problem can be solved by using GOTS or Oeko-Tex certified dyes.
Cons
The future is all about NMMO and the types of cellulose and derivatives that is can be used with. Below is the process of turning cutting room cotton scraps back into a usable fiber. The processes is called REFIBRA.

The future of Tencel has more to do with the NMMO solution. Since NMMO is non-toxic, easily made and 99% recyclable, the expansion of mixing it with different types of cellulose and its derivatives seems to be a hot topic.
Lenzing is currently in production with a new Tencel that uses a technology called REFIBRA. The process is exactly the same as Tencel but part of the cellulose input is derived from pre-industrial cotton scrapes - mostly from cutting rooms. Those scraps are turned into pulp and then blended with wood pulp. After that, the Tencel process continues as usual.
Benefits:
- Cotton scraps that are usually landfilled can be reused.
- Lenzing claims the ReFriba process uses 95% less water compared to conventional cotton. From my research, that seems well within the standard deviation of regular Tencel. No data exists on the comparison of REFIBRA and with the regular Tencel process.
The idea is extremely cool and while it’s new, it seems to have a huge potential. When talking to Innovation In Textiles, Tricia Carey of Lenzing mentioned, post-consumer waste is the next goal of the REFIBRA technology. If successful, the environmental implications would be tremendous! Remember, only fabrics or clothes derived from 100% cellulose would be applicable at the moment, polyester blends would not. I should note that more research is needed in the Life Cycle Assessment before a definite conclusion but I can only assume it will be positive as scraps are used instead of virgin materials.
Lastly, I was not able to find the exact amount of cotton to wood pulp ratio used in the REFIBRA process. I’m sure it’s proprietary. What I did find was that Lenzing’s Tencel using REFIBRA technology is part of Recycled Claim Standard which is a “chain of custody standard to track recycled raw materials through the supply chain.” From my understanding, the standard will track any product with 5% of its content being of recycled origin. Not significant but worth noting.
Final Thoughts
We like to imagine sustainable fashion as being 100% sustainable. However, it never really works like that. When creating and using any piece of fashion in this world, large amounts of energy, water and resources are needed. Honestly, nothing in fashion can truly be 100% sustainable. While that might seem to contradict to the term “sustainable fashion”, we find it as more of a guideline. When we create fashion, we create it with the purpose of being conscious of the environment. We strive to use resources that provide the least amount of harm to the planet and the people living on it. While that has many applications to different brands, consumers and environmentalist, we see it as a great starting point.
While we want to leave the question “Is Tencel Sustainable?” for you to judge... For us at Soluna Collective, Tencel will be part of our fabric mix now and into the future. It will not be the only fabric but it will be a part of our diverse mix!