Pouring concrete for the floor of a house extension, Ambleside, UK. (Photo by Ashley ... [+]
Every sector has its own set of challenges when it comes to reducing carbon emissions and going net zero.
But the construction sector has an even tougher mountain to climb than most, particularly as it consumes materials on an industrial scale.
For some people, the answer lies in moving to more sustainable materials like wood, but that might not be suitable for large-scale building projects or developing new infrastructure, like roads.
So, the question is can we make materials like cement and concrete in a more environmentally friendly manner? Would that help the construction move to net zero?
Iva Munro, senior manager at the international non-profit Climate Group, said in an email there can be no net zero without tackling concrete emissions.
Munro said concrete production accounts for around 8% of global carbon emissions, and that is only set to rise further over the next couple of decades.
“We’re already building a new Paris every week,” she told me.
“We need to improve data transparency to unmask the problem and accelerate innovation across the sector. We must also ensure that concrete is specified and used efficiently with sustainability at the forefront of the decision making.”
The international non-profit Climate Group, in partnership with World GBC, is currently urging businesses to join its ConcreteZero campaign and commit to using 100% net zero concrete by 2050.
“The good news is that many of the world’s most influential companies, including large construction firms, are already members of ConcreteZero, with new businesses joining constantly,” she added.
One company looking to spearhead the green concrete revolution is the Nordic/Dutch startup Paebbl, which has developed a process to take the carbon in CO2 and turn it into construction materials.
The co-founder of Paebbl, Marta Sjögren said in an interview the process involves adding an additional oxygen atom to the CO2 molecule, turning it to CO3, which in turn binds to a magnesium ion to form a solid carbonate mineral.
Paebbl adds water and ground silicate rocks to the carbon, and in a low-energy process producing a powder, which Sjögren added can then be used for a “portfolio of products and applications”.
The company is already producing small scale ultra low-CO2 SCMS, and by 2025, it expects to launch its first carbon-negative production unit.
The startup has chosen green supplementary cementitious materials as its beachhead product and she believes it could drastically reduce the carbon footprint of the construction sector.
“For every one tonne of CO2 we store through this process, we can generate roughly three tonnes of material,” she told me.
“There are so many use cases for concrete that the scale of this is quite significant.”
The company has already developed six generations of concrete that include its materials, with strong early performance results and is expected to go through the regulatory process for commercial use by 2025.
Fortera, a materials technology company based in California, has successfully devised a process capable of mineralizing carbon emissions from existing cement facilities providing the potential to reduce emissions by 100% - if combined with renewable energy sources.
Fortera co-founder and chief executive officer Dr. Ryan Gilliam said in an interview, “cement is the glue” that binds concrete together, and while cement typically only represents 15% of concrete materials, it makes up 80% of the CO2 emissions associated with concrete.
Dr. Gilliam said cement is made of limestone, which is heated in a kiln at very high temperatures.
Transforming limestone into calcium oxide in the kiln is energy-intensive, and it's where most of the CO2 emissions are emitted, he added.
“The work in the kiln is responsible for the majority of the carbon emissions in the full concrete production process,” Dr. Gilliam told me.
“That is why Fortera has developed a bolt-on solution that works with existing cement-making facilities to absorb those emissions, mineralize them and produce more cement. We are helping cement makers cut emissions by taking that industrial CO2 and turning it back into a usable product.”
Dr. Gilliam added that Fortera is near completion in building its first commercial plant that works in conjunction with CalPortland’s Redding, CA facility.
When that plant is fully operational, he added, it should produce 15,000 tonnes of green cement per year, which can be blended into traditional cement mixes at a rate of 15% for general use and up to 100% for preformed applications.
“From our experience in the construction world, there is a sincere desire to change and become more sustainable,” he told me.
“Everyone is looking for solutions and things that can be done, but those solutions have to be economically viable, and they need to work in the real world.”
“Our focus is not about trying to compete with the cement industry. We are here to support them and integrate seamlessly into their existing ecosystems. They want to make that change to go green, and we are here to help make that happen.”
