In the future there will be more vertical buildings to accommodate the growing population. However, making tall buildings, or any strong structure, needs materials like steel or cement which are not only costly, but also carbon-emissions-rich. 

According to a study by Rice University, building and using construction accounts for an estimated 40% of emissions. So, the researchers explored the possibility of using sustainable alternatives to existing materials that can reduce CO2 emissions and build buildings. 

Scientist Muhammad Rahman and collaborators have found a process to incorporate molecules of a carbon dioxide-trapping crystalline porous material into wood. Basically, they’ve made amped, engineered wood. 

Rahman said, “Wood is a sustainable, renewable structural material that we already use extensively. Our engineered wood did exhibit greater strength than normal, untreated wood.” 

Making more powerful wood 

In the study, published in Cell Reports Physical Science, the scientists explained how they’ve managed to develop stronger wood. First, the wood goes to a process called delignification.   

There are three essential components that make wood what it is: cellulose, hemicellulose and lignin. Lignin is the one that gives wood color, without it, the wood is now colorless. 

“Removing the lignin is a fairly simple process that involves a two-step chemical treatment using environmentally benign substances. After removing the lignin, we use bleach or hydrogen peroxide to remove the hemicellulose,” Rahman said. 

Second, the treated wood gets soaked in a solution that contains microparticles of a metal-organic framework (MOF). MOFs are one of the many materials developed to help mitigate climate change. They’re capable of taking up and holding substances—so they’re used to absorb carbon dioxide molecules into their pores. 

Lead author Soumyabrata Roy said, “The MOF particles easily fit into the cellulose channels and get attached to them through favorable surface interactions.” 

Per Rahman, there’s no biodegradable or sustainable substrate to deploy carbon dioxide-sorbent materials as for now. “Our MOF-enhanced wood is an adaptable support platform for deploying sorbent in different carbon dioxide applications,” Rahman continued. 

Roy added that many existing MOFs are not really stable when faced with varying environmental conditions. Some MOFs are sensitive to moisture—undesirable in a structural material. Their MOF type (CALF-20), however, has stood out when it comes to performance level and versatility.  

With this development, Rahman has expressed confidence in the team’s new, enhanced material.  

“Our process is simpler and ‘greener’ in terms of both substances used and processing byproducts. The next step would be to determine sequestration processes as well as a detailed economic analysis to understand the scalability and commercial viability of this material,” Rahman said. 

 

 

Will we have wood cities in the future? 

When we think of the distant future, we may think of tall, slim, white or metallic skyscrapers—you know, like what sci-fi media has ingrained such picture into our minds. 

Now imagine: what if the future won’t actually look like that? And instead, we’ll see wooden, organic-shaped cities?  

I mean, Rahman’s study suggested that their engineered wood could be a great material for the future. More people will also think twice before building a construction, considering the environmental impacts and costs first. 

And well, another study by researchers at Aalto University and the Finnish Environment Institute suggests that shifting to wood as a main construction material will reduce the negative impact of building construction significantly. 

The Finnish study shows that if 80% of new residential buildings in Europe were made of wood, and wood were used in the structures, cladding, surfaces, and furnishings of houses, the buildings would store 55 million tons of carbon dioxide a year. 

To put it into perspective, 55 million tons of carbon is the equivalent of around 47% of the annual emissions of Europe’s cement industry. 

According to one of the authors, Ali Amiri, this study is the first one to evaluate carbon storage potential of wooden building construction on the European level. “We hope that our model could be used as roadmap to increase wooden construction in Europe,” Amiri said. 

Looking from case studies 

The Finnish study is based on an extensive analysis of 50 case studies from different literature. The researchers divided buildings into three groups according to how much wood they use, and consequently, how much CO2 stored. 

They categorized one with the least amount of wood stored 100 kg of carbon dioxide per square meter, the middle group stored 200 kg, and the group with the greatest amount of wood stored 300 kg per square meter. 

This capacity to store carbon wasn’t caused by wood type, or even its size, but rather based on the number and volume of wood used as building components, like the beams, walls, and finishings. 

 

 

According to the researchers, Europe has the potential to achieve CO2 emission cut by modelling a path for reaching the level of 55 million tons per year by 2040.  

Let’s say that in 2020, 10% of new residential buildings were made of wood, each storing 100 CO2 kg/m2. Then, wooden buildings would need to grow to 80% by 2040. 

Amiri added that there should be an awareness about the benefits of wood when people in the future want to build energy-efficient buildings. 

“Certificates for green buildings used around the world, such as LEED and BREEAM, could better take the climate benefits of wood construction into account. So far, they are strongly focused on how energy is consumed during use,” Amiri said. 

But won’t wood rot or burn? 

So far, you’re not too sold on the idea of wooden buildings, let alone wood skyscrapers, because wood is known to burn easily and is so prone to moisture, so there will be risks of deterioration.  

Such concerns are understandable. Many of the old buildings made from wood didn’t survive fire—in AD 64, the Great Fire of Rome lasted for six days. In 1674, the Great Fire of Meireki destroyed the capital city of Edo, claiming over thousands of lives. Let’s also not forget the Great Fire of London in 1666.  

All those great fires happened because the buildings were mostly wooden. And since then, to prevent fire, stone and brick were much more preferred than wood. Of course, one would frown about the idea of going back to building structures with wood. 

However, modern wood buildings won’t take straight-up wood or timber. They will use engineered wood, much like Rahman’s innovation.  

Besides, there’s a study by the Committee on Tall Wood Buildings. They tested two one-bedroom apartments made of engineered wood at the Fire Research Laboratory, Virginia. 

After the researchers set the apartments on fire, they found that the fire raged until it had burnt through the furnishings, then extinguished itself. The contents of the apartments were devastated, but the structure itself was, to put it simply, unscathed. 

As for rotting, well, treated wood (not engineered) is incredibly resilient—we just need to keep it from getting soaked wet. And maybe in the future, engineered wood will have water resistant or waterproof properties. 

To give you a picture, the Sakyamuni Pagoda of Fogong Temple in China is fully wooden. Due to skillful craftsmanship and sturdy design, it’s still standing 900 years later, surviving at least 7 serious earthquakes.  

 

Sources

https://www.sciencedaily.com/releases/2023/02/230216172203.htm   

https://www.sciencedaily.com/releases/2020/11/201102110010.htm   

https://www.bbc.com/future/article/20171026-the-rise-of-skyscrapers-made-of-wood