The paper is incredibly helpful in the way it outlines the enormous opportunities for carbon storage in building materials.

Australia has a high scope 3 emissions exposure through its importation of the world's single largest source of carbon emissions, being Portland Cement clinker from Japan, Malaysia, and Indonesia for use in buildings and road construction. Yet Australia disposes of enormous volumes of mine tailings from iron ore, lithium and bauxite processing and many other minerals that could be used, as the paper describes, for new building materials without the need for Portland cement. In turn, this aids the transition to Circular Economy, something that the paper has not mentioned. 

My teams work in the development of a new low-carbon geopolymer concrete to replace Portland cement, which we called Colliecrete after the town from which it sourced its coal fly ash. This Colliecrete is now being commercialised by Suvo Strategic Minerals and production trials are underway in WA at the state’s largest precast concrete factory, Permacast. In this industry-partnered environment we are also developing new technologies for new low-carbon concrete production that also reduce our dependency on imported high-carbon building materials like Portland cement from the first Industrial Revolution 200 years ago. 

We are also developing new low-carbon concrete products with our partners in Indonesia from the enormous volumes of nickel slag waste being generated there and abandoned in enormous stockpiles that threaten local environments and communities. 

Meanwhile in our nearby SE Asian countries like Sri Lanka, from where I have just toured and met with local researchers and cement industries, there are enormous volumes of ash disposed of from biomass boilers that can be harnessed and used in low-carbon concrete production and bricks as the paper describes. New partnerships are being created here and in Vietnam to enable this work to start. 

This paper is critically important for the next stages in the construction industry being able to play their part in the net zero economy. We have solved the solar, batteries and EV’s in urban development and we just need simple ways to add decarbonized materials into the buildings, roads, pathways of our cities, to begin truly having a full net zero approach. The data collected and analysed on each of the materials are very helpful and the analysis shows that this is a high potential opportunity that we must take.

Clearly there are significant steps that need to be taken with certification and safety issues needing to be resolved. The idea of starting with non-load bearing materials to help establish the industries as the R&D is conducted on all the engineering standards, is a commonsense approach. I think the opportunity for Australian builders and construction material providers to start down the net zero journey using these new materials, is one that should not be missed. It has all the character of a major breakthrough in delivering net zero cities.

The construction industry is a conservative industry and therefore requires certainty before it will invest in new materials. Certification of products usually provides this certainty. However, the industry tends to make choices for material options mainly using criteria of cost, time, and quality, with safety as paramount, and environmental considerations important. So, even if carbon sequestration using new materials is desired, there are obstacles which would prevent use. For instance, would the material cost more to procure? Does it require new training for staff? If so, it is unlikely to be preferred over traditional materials. Would it take more time to install or have a longer supply chain? Again, it would be hard to see a preference over traditional materials. Would quality be compromised? If there is a negative change in quality, then this impacts decision making.

"Other than satisfying choice criteria, there are ways to achieve change, some of which (and these are not all) include educate clients to ask for new certified materials, legislate for their use, or use tax or trade agreements to reduce costs."

This article concludes that by changing the types of materials we build with, we can help large amounts of carbon dioxide to be drawn out of the atmosphere. This process is 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.

"Other removals described in the article 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.

"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.

The premise of the paper is promising: given the massive volume of infrastructure materials produced annually and their long lifespan in service or landfill, construction materials indeed offer substantial potential for carbon storage.

"However, the paper’s assumptions about carbon storage capacity in various building materials appear to favour masonry materials at the expense of wood-based alternatives. The comparison between existing (wood-based) materials and those that do not exist at scale yet is unrealistic. To be accurate, a comparison would need to consider wood-based materials at the same stage of development as other future materials mentioned in the paper.

"There is no substantial evidence to confirm these proposed modified non-renewable materials will be commercially available in the future, while wood-based alternatives have long been established as renewable building materials. Timber, for example, has a long history of proven performance, and its benefits as a carbon sink are well documented.

"It is crucial to recognise trees are restored by nature, while other building materials are more likely to remain in landfills and the sites mined for minerals will not be restored. It is crucial to emphasise that the use of modified non-renewable building materials in combination with wood-based building materials that sequester carbon long term will help reduce the devastating effect of greenhouse gas emissions.

"Scion’s research ensures wood-based materials increasingly contribute to sustainable buildings. Its Rotorua innovation hub, Te Whare Nui o Tuteata, demonstrates this. The timber structure is carbon-neutral, storing 418 tonnes of CO2 – equivalent for the life of the building – equivalent to the emissions from 160 people taking return flights from Auckland to London.