Bamboo is a fast-growing crop that thrives almost anywhere in the world. Because it grows rapidly, it absorbs a lot of CO2 from the atmosphere, which is an attractive option for CO2 compensation. But bamboo also has a number of other applications. One of them is fibre-pressed bamboo. This is a composite material that resembles ordinary wood, but is harder and more durable than tropical hardwood. In modern residential construction, we almost exclusively use concrete. A lot of CO2 is released during its production. With bio-based construction, concrete can be replaced by wood, or even better: by bamboo!
Bamboo in the Netherlands
Bamboo grows almost everywhere in the world, but thrives best in warm climates. There, this crop can reach a height of up to 20 meters. But bamboo cultivation is also possible in a temperate climate, such as in the Netherlands.
Fibre-pressed bamboo
Bamboo is widely known for the characteristic rings on its trunks. But the most valuable part of a bamboo stem is inside. These are the fibres that run from the ground to the top of the plant. When a bamboo stem is split open from top to bottom, one is left with flat, long slats in which all the fibres are arranged parallel to each other. By placing these slats next to each other, impregnating them with glue and pressing them together under high pressure, we obtain a composite material that looks like ordinary wood, but is substantially stronger. This is called ‘fibre-pressed bamboo’ [2]
(https://www.inbar.int/wp-content/uploads/2020/05/1541657603.pdf) [3]
Fibres are found in many crops. Anyone who has ever removed nettles in his garden knows that you can’t just break the stem of this prickly plant in half. That’s because of the fibres. Flax and hemp also have similar fibres, but the trunks and branches of trees do not. By the way, ‘fibres’ is a somewhat confusing name, because there are so many types of fibres. Another word for fibres in plants is ‘strands’. That is why fibre-pressed bamboo is also referred to as ‘strand-woven bamboo’, abbreviated as SWB.
On Dutch TV
Last October, the Dutch TV program ‘Tegenlicht’ had a broadcast about biobased construction with ample attention to fibre-pressed bamboo [4]. They also published a podcast on this subject with a clear explanation of the essence of this composite material [5]. The TV program Focus also broadcast a report on biobased construction last October, but it did not discuss fibre-pressed bamboo [6].
Biobased construction is clearly on the rise in the Netherlands!
(https://www.change.inc/infra/biobased-bouwen-zit-in-de-lift-maar-houten-wolkenkrabbers-kosten-te-veel-bomen-41204) [8]
Bio-based construction
In the US and Scandinavia, a lot of construction is done with wood, but concrete is the norm worldwide. Houses have been built of wood since time immemorial, but they are rarely higher than two to three storeys. Due to the growing world population, more and more people live in apartment buildings of four floors or higher. Almost all these buildings are made of concrete.
However, that can also be done with wood. An innovation that has proven to be extremely helpful in this development is the introduction of cross-laminated timber (CLT) [7]. But perhaps the biggest innovation is fibre-pressed bamboo, because it seems to surpass all other types of wood in strength properties. This makes lighter building constructions possible, and also lower building costs. And it increases, where applicable, earthquake resistance.
Obviously, bio-based construction is nothing else than building with materials that come from the land, such as wood or bamboo. In my view though, this term indicates that it does not refer to a traditional timber construction, but to a development that makes use of all kinds of innovations. These focus not only on the construction of residential houses, but also of larger residential units, such as apartment buildings.
What biobased builders are concerned about is the question of whether there will be enough wood available for this approach [8]. The answer to this question could very well be bamboo, because this crop grows quickly and can be harvested after 5 years, whereas a tree needs at least 30 years to do so.
CO2 emissions
Concrete is prepared by mixing cement with gravel, sand and water in a weight ratio of around 1:7 [9]. One ton of cement contains 60% or 0.6 tons of lime (CaO) [10]. This consists of 0.45 tons of calcium (Ca). Limestone is mined in limestone quarries and has chemical formula CaCO3. After excavation, it is converted into lime (CaO) and CO2 at a high temperature.
- CaCO3 => CaO + CO2
Together with a number of other components, the lime formed is mixed into cement. With a molar mass of 44 g/mol for CO2 and 40 for Ca, in total 1.1 tons of CO2 are released for every ton of calcium. This corresponds to 0.5 tons of CO2 for every ton of cement. Up to 60% of the CO2 emissions of the cement industry come from the chemical process, i.e. the conversion of limestone into lime and CO2, and 40% from the burning of fossil fuels [11]. This means that in addition to 0.5 tons of CO2 for the chemical process, another 0.3 tons of CO2 are released by the fuel, which is needed for the high process temperature. This amounts to 0.8 tons of CO2 per ton of cement. Hence, per ton of concrete, which consists for 1/7th part out of cement, 0.15 tons of CO2 are emitted.
Because the global production of cement totals more than 4 billion tons per year (Gt/y) [10, 12], this amounts to over 3.2 Gt/y CO2. We, humans, emit 40 Gt/y CO2. This means that about 8% of this amount is accounted for by the production of concrete. This is in line with the 6 to 10% mentioned by Wikipedia [10, 11]. An EU-funded website on concrete starts with: ‘Worldwide, it is estimated that more than 25 billion tons of concrete are used annually’ [13]. Because 4 times 7 equals 28, this estimate of ‘more than 25 Gt/y concrete’ is well in line with ‘more than 4 Gt/y cement’.
CO2 absorption
Fibre-pressed bamboo consists of about 40% the element carbon (C). That equals 0.4 tons per ton of biomass. With a molar mass of 44 g/mol for CO2 and 12 for C, a tree or plant sequesters a total of 3.67 tons of CO2 in the form of biomass for every ton of carbon. For 1 m3 of fibre-pressed bamboo, which corresponds to 1 ton of this composite material, 1.5 tons of CO2 are thus removed from the atmosphere.
At present, bio-based construction could replace about half of the required concrete with fibre-pressed bamboo [14]. An average new-build house in the Netherlands contains between 100 and 300 tons of concrete, let’s assume 200 tons. When replacement is possible, an average of 1 ton of concrete can be replaced by 0.3 tons of bio-based material [14]. For the production of 1 ton of concrete, 0.15 tons of CO2 is emitted, while 0.3 tons of bio-based material store 0.45 tons of CO2. This means that replacing 200 tons of concrete with 100 tons of concrete and 30 tons of fibre-pressed bamboo avoids the emission of 60 tons of CO2 in total. Given current developments, it is expected that this biobased share will increase further in the future [14]. With an annual production in the Netherlands of 50,000 to 100,000 new-build homes, this can save 3 to 6 million tons of CO2 per year.
In the hypothetical case in which the above-mentioned amount of 25 billion tons of concrete per year worldwide could be completely replaced by bio-based material with the same replacement factor of 1 in 0.3, 7.5 billion tons of biobased material would be needed. It is mind-boggling to consider that this would lead to a reduction in global CO2 emissions by 15 Gt/y, equating more than one third of current total global CO2 emissions of 40 Gt/y. Building with fibre-pressed bamboo is not only beneficial for our wallet, but it also is highly advantageous for our climate.
Price comparison
Finally, costs. The price of 1 m3 of concrete is around € 150 [15]. At a density of 2.4 tons/m3 [10], this equals € 60 per ton. It is not unreasonable to assume that 1 m3 of fibre-pressed bamboo will be at the same price level as maize, which costs € 100 to 200 per m3 [16, 17]. But only 0.3 tons of this biobased material is needed to replace 1 ton of concrete, costing € 30 to 60. This means that on the average bio-based construction is cheaper than building with concrete.
In addition, the lighter weight results in a further decrease in costs. For example, lifting work of the prefab parts requires less energy, making electric hoisting possible. In this way the emission of harmful nitrogen-derivates can be prevented (this is a regulatory issue in the Netherlands).
Is there enough biomass?
Above, I describe that the annual global production of 25 billion tons of concrete could be replaced by 7.5 billion tons of biomass in the form of bio-based materials such as fibre-pressed bamboo.
The next question is: Can our planet produce this gigantic amount of biomass?
It is useful to remember that food is also biomass. Every person needs at least 100 kg per year of basic food, in the form of grain, maize or rice, to survive. For 8 billion people, this amounts up to 800 million tons per year. On top of that comes animal feed, for which maize and other crops are grown and which involves even larger quantities [18].
I find it very difficult to answer my question from the above. Nevertheless, I think it is plausible, that Nature could produce at least a considerable part of it. This assumption is confirmed by a 2019 study by the University of Zurich (ETHZ) on the gigantic potential of reforestation on a global scale [19].
Conclusions
Building with fibre-pressed bamboo is certainly not more expensive, and probably even cheaper than building with concrete. When it comes to our climate and CO2 emissions, there is a lot to be gained from bio-based construction. Fibre-pressed bamboo can play a major role in this development.
Acknowledgements: I would like to thank Klaas Dijksta, owner of the Dutch construction company Green Wood International, for data on the use of concrete and fibre-pressed bamboo in residential construction.
References
[1] https://www.degroeneprins.nl/botanische-tuin/
[2] Pablo van der Lugt, Booming Bamboo (2017), ISBN 978 90 827552 2 0
[3] Pablo van der Lugt et al. (2018), Carbon sequestration and carbon emissions reduction through bamboo forests and products (INBAR working paper), https://www.inbar.int/wp-content/uploads/2020/05/1541657603.pdf
[4] https://www.vpro.nl/programmas/tegenlicht/kijk/afleveringen/2024-2025/bouwen-met-de-boer.html
[5] https://www.vpro.nl/programmas/tegenlicht/lees/artikelen/2024/bouwen-met-de-boer/het-bijzondere-van-bouwbamboe.html
[6] https://npo.nl/start/serie/focus/seizoen-7_1/focus_43/afspelen
[7] https://www.change.inc/infra/houtbouw-van-nu-is-niet-te-vergelijken-met-de-middeleeuwen-39736
[8] https://www.change.inc/infra/biobased-bouwen-zit-in-de-lift-maar-houten-wolkenkrabbers-kosten-te-veel-bomen-41204
[9] https://www.vtwonen.nl/verbouwen/zelf-beton-maken-zo-krijg-je-een-bikkelhard-eindresultaat~4205a14
[10] https://de.wikipedia.org/wiki/Beton
[11] https://nl.wikipedia.org/wiki/Cement_(bouwmateriaal)
[12] https://cementenbeton.nl/co2-roadmap-cement-en-beton-in-nederland/
[13] https://interregvlaned.eu/beton-naar-hoogwaardig-beton/over-ons
[14] Personal communication by Klaas Dijksta, owner of the Dutch construction company Green Wood International
[15] https://www.checkatrade.com/blog/cost-guides/ready-mix-concrete-cost/
[16] https://www.bloomberg.com/markets/commodities/futures/agriculture
[17] https://www.macrotrends.net/2532/corn-prices-historical-chart-data
18] Rolf Heynen, Het kan dus wel (2022), ISBN 978 90 213 4023 4
[19] Jean-Francois Bastin et al., The global tree restoration potential, Science 365, 76–79 (2019), https://www.science.org/doi/10.1126/science.aax0848