Here is the full text of David Trujillo’s talk titled “Bamboo: 21st century steel” at TEDxCoventryUniversity conference. In this talk, he explores the potential bamboo creates and how well it can be a wonderful and strong tool.
David Trujillo – TEDx Talk TRANSCRIPT
Thank you very much.
Imagine a material. That is beautifully engineered. That to produce it, it will consume minimal energy. That actually sinks carbon dioxide. And it simply grows.
We don’t have to manufacture it. And we can harvest it in 3 to 5 years. And in the process, it will employ millions of people in rural communities in the developing world. And it is very cheap.
There is a material. It’s bamboo.
Bamboo has thousands of applications which range from paper, kitchen utensils, floor boards, clothing, and even allegedly, the bristles in this toothbrush contain bamboo derived charcoal.
However, speaking as a structural engineer, what fascinates me about bamboo is just in its natural shape. As I said, it’s beautifully engineered. Take its shape. The fact it’s hollow, instead of solid, makes it four times more efficient. Its nodes conceal diaphragms. They stiffen the walls of the elements.
So, it buckles less. So, it’s less likely to buckle. And they are closer together where they’re most needed. Its fibers are three times stronger than structural steel. And they are very cleverly distributed.
For example, in the wall, they are concentrated towards the perimeter making the section 10% more efficient than if they were just randomly distributed.
You might be asking, “Well, yeah that sounds interesting. But how does that compare against man-made materials?”
So, let’s do like a thought experiment. How much would this piece of bamboo take? What would be the maximum safe working load of a 3 meter beam made out of bamboo? That would be roughly around 290 kilograms.
So now, how would that compare to say steel? Well, if we limited ourselves to commercial sizes of steel, a steel section that would achieve the same safe working load would be about that size, which is smaller.
You’ll say, “So, it’s not very fair comparison you’ve going up to do, David. Let’s do something a bit more comparable.”
So, I’ve dreamed up a size that you can’t buy, you’d have to have specially made, but there is no reason why we can’t assume it, which would be this size: 84 mm diameter.
So how do they compare? How do these materials compare?
So, in terms of mass, the hypothetical steel section would weight around 7 kg. The commercial one, the one that we really can buy, would weigh around 10 kg.
Whereas the bamboo one would weigh just short of 6 kg. So, in terms of strength to weight ratio, bamboo is as good or if not better than steel, which is pretty impressive.
However, what really matters is cost. And the currency I’m going to tell you about is carbon dioxide.
So, the carbon emissions associated with making these sections would be, around 10 kg for the hypothetical steel section. Around 15 kg for the commercial size section.
And if this bamboo is used within 500 km of where it was sourced, it would be just 1 kg. So that’s really, a substantial difference in terms of efficiency.
However, there’s more. This piece of bamboo stores within it, around 10 kg of carbon dioxide with equivalent of. That means, considering the 1 kg we use to process it that we’re storing, we’re capturing from the atmosphere 9 kg of carbon dioxide.
Which means that if I choose to make this beam out of bamboo, instead of steel, we would be making a saving of around 19 kg of carbon dioxide. That equates to the emissions produced by an average European car over 150 km.
Now, this carbon storage only remains for as long as that piece of bamboo is in a permanent structure. But say, if 50 years down the line, we demolish this structure and then we burn the bamboo, we go back to this situation.
Because the 10 kg will return to the atmosphere. Still better than steel, but not as good as this.
So, however, if we burned it and generated electricity, for example and in the process avoided burning a fossil fuel, which will introduce new carbon dioxide to the atmosphere, it would be sort of equivalent of making this storage permanent.
Now, if there were someone from the timber industry here, they would say, “Hang on, that’s true also for timber.” And it is.
However, bamboo has one key difference with respect to timber… is that it takes 3 to 5 years to be harvested. It only takes 6 months from the moment it emerges to reach its full height up to 20 or 25 m.
So, in the war against carbon emissions, bamboo is a weapon that we can deploy sooner. And bamboo has other environmental qualities. For example, its forests have a complex root network that control erosion and regulate the water cycle.
And by the way we harvest it, in which we only extract some of the mature columns, in the forest wild life can find sanctuary.