Worldwide, staple crops including maize, wheat and rice produce 3.3 billion metric tonnes of residue. Mostly, this is burned for energy, releasing vast amounts of CO2. A new study proposes an alternative: what if we instead use this abundant waste to make building materials?
The embedded carbon would be locked away for decades, put a dent in agricultural emissions—and even cool down the planet, its researchers find.
Crop waste like wheat straw and rice husks is already used to make bio-insulation, among other building products, but only in tiny percentages. The researchers wanted to take this niche idea and look at the global climate effects if it went mainstream. To start, they took estimates of the available global agricultural residues. Then they simulated different scenarios, where those residues were either burned for energy and made into animal feed, or not burned and used for other purposes like building materials, to varying degrees. They also looked at how demand for biomass as building materials would change the picture.
With a lifecycle approach, they were able to reveal the true climate benefits of these measures. And crucially, they looked beyond avoided emissions to explore how those would increase the radiative cooling effect that occurs with less CO2 being emitted into the atmosphere.
The findings were striking. First of all, they revealed that if we stopped burning all crop residues (and if the energy lost from burning was replaced with renewable energy instead), it would generate a radiative forcing effect large enough to reduce global temperatures by 0.35 ◦C over 100 years. In other words, not burning crop waste would actually cool the planet. “The scenario leads to a small but persistent cooling effect that builds up gradually and is still present after a century,” explains Bamdad Ayati, a materials chemist and senior research fellow at the University of London, and the study’s lead author.
Then the team looked at what could be achieved if we relied on the global residue demand to make bio-insulation. But here they found that even the most ambitious scenario reflecting real demand would only divert 40 million tonnes of dry agricultural residue at most each year—less than 1% of what’s available. In other words, the market is currently too small to significantly turn the dial on this problem. Simple stopping opening burning, meanwhile, could achieve much more, in climate terms. “Avoiding this single high-emission practice has a much larger climate effect than insulation material demand alone,” Ayati says.
The takeaway, says Ayati, is twofold. The first and most urgent step would be to eliminate carbon-intensive residue burning globally. And secondly, even though crop-waste-to-building-material is currently a niche application, it could grow significantly if governments started “reducing regulatory and market barriers,” Ayati believes.
And why stop at insulation? Crop waste can be used in the production of panelling and boards, bricks and even cement, potentially locking away tons of carbon in the buildings of the future.
Ayati et. al. “Dynamic life cycle assessment of fibrous agricultural residues for long-lived carbon storage in building materials.” Cleaner Environmental Systems. 2026.
Image: Holcim Foundation
link