Switching up our building materials could store more than 16 billion tonnes of CO2 annually, according to a new study in Science
A team of US researchers calculated that fully replacing conventional building materials in new infrastructure with CO2-storing alternatives could store as much as 16.6 billion tonnes of CO2 each year—roughly half of human-caused CO2 emissions in 2021. These alternatives include mixing carbon aggregates in concrete or using bio-based materials in bricks.
University of Canterbury Associate Professor David Dempsey says this will help draw large amounts of carbon dioxide out of the atmosphere – a process called carbon removal.
“The largest removal by far comes from a new kind of concrete that includes a special CO2-capturing aggregate like dunite rock, of which New Zealand has bountiful natural deposits in Nelson and Southland. But this concrete capture would need to be paired with high purity atmospheric CO2, for which the best options in New Zealand would be the flue gas coming from a biomass boiler (we have a lot of these too). We’d also need to carefully check that the new concrete was just as strong and durable as existing uses.
He says other removals described in the study come through clever substitution of forestry-derived materials.
“Again, New Zealand has natural advantages with our large forestry sector and the widespread use of timber in construction materials.”
Dempsey says a few things would need to change for New Zealand to capitalise on this research.
“First, the government would need to change the rules to recognise carbon embodied in building materials, for instance by issuing NZUs under the emissions trading scheme.
“Second, we’d need to think carefully about just how long the CO2 is actually stored for and what happens to it once the building is torn down. If the CO2 is later released from the landfill, then this is kind of storage is limited.
“The amount of CO2 storage needed worldwide is daunting and so storage in building materials deserves to be on the table alongside approaches like geological storage, further forestry planting, and other nature-based solutions,” Dempsey says.
See the full report on the study: Building materials could store more than 16 billion tonnes of CO2 annually | Science
