Knock on wood

Forget plastic: This see-through wood material is millions of times more sustainable

Move over, polyethylene.

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This is a drone photo of trees in the forest.
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If you’ve ever used a paper straw, you know the singular disappointment of trying to sip a refreshing beverage through a soggy, slowly collapsing tube.

Of course, the alternative isn’t much better: Plastic straws may offer a satisfying drink experience, but each one we use adds to the roughly 8.3 billion polluting beaches around the globe.

But what if there was a wood-based plastic alternative that held its own against your beverage of choice? Turns out, there is — transparent wood.

This futuristic material is flexible, moldable, and see-through, just like traditional petroleum plastics. But rather than being derived from fossil fuels that worsen climate change, it’s mostly made of trees.

Transparent wood could make its way into your straws (and other daily items) and prove far more eco-friendly than plastic.

Dhar et al.

“Wood is one of the most widely produced natural materials on Earth, making it a suitable alternative for fossil fuel-derived materials,” says Prodyut Dhar, a biomaterials engineer at the Indian Institute of Technology Varanasi.

A recent review by Dhar and colleagues published in Science of the Total Environment suggests that transparent wood holds serious potential for reducing carbon emissions.

The researchers found that wood-based materials are up to 10 million times more sustainable compared to polyethylene, the most widely produced plastic in the world. They also assessed five different manufacturing techniques for transparent wood to determine which was most ecologically friendly.

Though the technology has yet to go mainstream, it could replace our iced coffee straws in the not-too-distant future.

Here’s the background — Transparent wood was originally developed in the early 1990s as a way to study a plant’s xylem and phloem (roughly equivalent to our veins and arteries) intact without destroying the specimen.

In the mid-2010s, scientists revived the technique when searching for a sustainable alternative to petroleum-based plastics. Today, transparent wood can be produced in a number of ways, but most are based on a process called deligninification.

Wood is made up of two major components: cellulose and lignin. Cellulose fibers are the flexible, waterproof building blocks that give plants their tensile strength. Lignin acts like the glue that binds these fibers together. It also holds chromophores, pigment-containing cells that give wood its rich brown color.

This new material is far more sustainable than the widely-used plastic polyethylene.


In order to make transparent wood, scientists usually dissolve and replace lignin with another transparent material, such as epoxy or acrylic glass. “Since wood is really strong, we can use [a] relatively weak material” to combine it with, says Peter Olsén, an organic chemist at the Royal Institute of Technology in Stockholm, Sweden, who wasn’t involved in the new study.

But not all deligninification processes are created equal — some use volatile chemicals to strip out lignin, while others require massive amounts of energy. And some replace lignin with petroleum-based plastics rather than bio-based ones, which cuts back on fossil fuel reliance (but doesn’t eliminate it).

What’s new — In their review, Dhar’s team examined the five different methods to create transparent wood and compared them across eighteen different metrics, including how much energy went into production and the amount of carbon released, along with freshwater consumption, recyclability, and potential toxicity.

This helped them determine which was the most environmentally friendly. Of all the methods they evaluated, the researchers found that dissolving the lignin in an alkaline solution and replacing it with epoxy proved the greenest from start to finish.

Transparent wood is exponentially cleaner than polyethylene.

Tanja Ivanova/Moment/Getty Images

Why it matters — Not only did this path produce the least pollution, but the chemicals involved are cheap, according to Dhar. This means that transparent wood production should be relatively inexpensive to scale up, according to his team’s review.

Finally, the researchers evaluated the environmental toll of this particular transparent wood compared with the conventional plastic that makes up commonly used items like single-use trash bags. They found that it was exponentially cleaner than polyethylene, marking it as a promising candidate for the green revolution.

It’s important to note that transparent wood requires, well, wood, and massive production could potentially contribute to deforestation — yet Dhar and his team did not factor in this possibility to their overall environmental impact ranking

What’s next — Despite its promise, transparent wood isn’t currently churned out outside of the lab. “[The] technology is still in the research and development stage,” Dhar said.

But scientists have used it to make all sorts of proof-of-concept products, from flexible electronics, walls, energy storage devices, and packing material. It even has the potential to make shatter-proof windows.

Of course, to make transparent wood truly eco-friendly at a large scale, the manufacturing process should be powered by renewable energy, like solar or wind power.

Scientists will also need to make sure they aren’t simply replacing lignin with a petroleum-based material. “The key here, obviously, is to use plastic that is also bio-based,” Olsén explains.

But as more and more researchers dig into transparent wood’s potential, “it will only be a matter of time till we see real-life applications,” he says.

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