We are building many, many buildings. Not only public space projects, but also housing to accommodate a population that will continue to grow until at least 2080. That will be when we reach the peak of 10 billion people and, of course, when we think of “construction”, the word “concrete” goes hand in hand. The problem is that, to get concrete, we have to make cement, a process that is not only very polluting, but is also depleting sand reserves worldwide.
That is why alternatives are needed and there are those who are making them. For example, we have masonry bricks and plastic fasteners to secure the structure. Also, cement made from shells. But the solution may be the old reliable: wood. This material that we have been using for millennia has become fashionable again, but the truth is that it is not the same wood that our ancestors used to build the great cities that, in many cases, ended up being consumed by the flames.
Thanks to different experiments and techniques, we are greatly improving wood and its properties. So much so that the latest trend is a wood developed at the University of Maryland that has two properties: it pollutes less than concrete and helps trap atmospheric CO₂.
Its secret? It is transgenic.
Back with the wood
The truth is that wood began to become a viable alternative to concrete a few years ago. In 2022, the United States had completed a nearly 90-meter building that was built with wooden pillars. It was cross-laminated timber – or CTL – combined with laminated timber beams – or glulam – and the advantages were several. On the one hand, the construction time was reduced by approximately 25%. In addition, there is no need to ‘dress’ that wood and approximately half of the structure is exposed, which serves as a façade and interior decoration.
Wood also has advantages when it comes to insulating against both cold and heat, but the most interesting thing is that it is much more sustainable than concrete. Other cities are going to follow this example and, at that time, Switzerland set out to break the height record with a 100-metre wooden skyscraper.
And, among the factors already mentioned, this ‘revival’ of wood has to do with its new properties. We are investigating how to make it as strong as steel alloys and we are even experimenting with transparent woods that would not only reduce costs when creating buildings with large windows, but would also be a natural insulator. But it seems that there are those who think that wood could do even more for us.
One example is researchers at Cambridge University, who recently discovered that there were trees that were incredibly effective at trapping atmospheric carbon. Thanks to their internal structure, the ‘tulip tree’ – Chinese Liriodendron and Liriodendron tulip- They were shown to be ideal for sequestering carbon. Of course, the research focused on the importance of this type of tree for, for example, replanting forests or areas in cities that would become real CO₂ traps.
But what if “dead” wood could serve the same purpose and be used to build houses while capturing carbon? A team of researchers from the University of Maryland have managed to produce a wood that is 1.5 times stronger than untreated natural woodBy genetically modifying poplar, they have been able to produce high-performance wood that does not require chemicals or energy-intensive processing to be denser and have better properties than standard poplar wood.
The key is held by Yiping Qi and Liangbing Hu, the professors who have directed the project. Thanks to A technique for modifying the 4CL1 gene of poplarsthe resulting wood had 12.8% less lignin, a compound that must be removed using chemicals if we want the wood to be optimal for construction. It fulfills its function in nature, as it is a polymer that helps stabilize the structure of plant cell walls to improve the transport of water and nutrients.
That is, in the process of obtaining optimal wood for construction, by eliminating lignin during the growth of the tree, we already avoid contamination due to the chemicals used in the wood conditioning phases, but this is not the only advantage. As we said, the analyses showed that this wood was denser and more resistant to traction than aluminium (specifically, to the 6061 alloy, which is widely used in construction).
And interestingly, the transgenic poplars matured next to other non-genetically modified poplars for six months in the greenhouse. At no point did they show any differences in structure or growth rates. Therefore, the new transgenic poplar wood It is not only better than the natural variantbut by not having to treat it with chemicals to eliminate lignin, we pollute less in the process.
A next step, Professor Qi says, is to study whether similar results can be obtained in other types of trees.
The truth is that more and more people support the idea of building cities of the future out of wood. With the knowledge we have, it is a very interesting material to help with decarbonisation objectives. Another thing will be if the wood used is not… well, like the wood used in ancient times.
Images | Nina Rundsveen, Juan Emilio Prades Bel
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