Where would we be without concrete?
Two-thousand years after the Romans conquered the Western World, their monuments are still caressed by the sun. Ageless, they have withstood the rise and fall of their surrounding cities and generations, and inspired both to build towards an equally ageless ideal. Concrete is progress, the spine of the modern world. It is so ubiquitous, in fact, that its manufacture accounts for a significant portion of global carbon emissions.
The problem is cement. Though often used interchangeably, cement and concrete are not the same thing. Cement is one ingredient of concrete (essentially the paste that binds it together), made by heating limestone and other materials to extremely high temperatures and then grinding the resultant substance (called “clinker”) into powder. This energy intensive process produces carbon dioxide in two key areas: The chemical reaction that creates clinker and the fossil fuels burned to heat it up. Ninety percent of the carbon produced by the cement industry is emitted in this process; the remaining 10 percent of the industry’s carbon footprint derives from electricity use and transportation.
According to the United Nations Environment Programme, concrete is the second-most consumed substance on the planet, after water. Its indispensability means demand for cement is always high, and thus the industry now produces about five percent of global man-made CO2 emissions.
With the effects of global warming becoming increasingly apparent – longer dry seasons, more intense hurricanes, rising sea levels, food shortages – political and business leaders are eager to cut back on carbon wherever possible. Concrete’s chunk of the carbon footprint only exists because it’s produced in such large quantities (approximately three tons of concrete exists for every one human on Earth). So the solution is simple: Either use less concrete or find a carbon-friendly alternative to clinker.
Nobody’s keen to build fewer buildings, so how do we make better cement?
UCLA Is on the Job
Dr. Gaurav Sant doesn’t mince words. When I asked him if the cement alternative his researchers created could be scaled up to commercial size, he answered brusquely, “Of course it can. We’re not bending time and space.”
An Associate Professor and Henry Samueli Fellow at UCLA’s Department of Civil and Environmental Engineering, Sant is one of five faculty members leading the Carbon Upcycling team. Their new building material, CO2NCRETE, would use carbon emissions from power plants to produce a cement-like substance to replace clinker.
This month, Carbon Upcycling advanced to the semifinal round of the Carbon XPRIZE, a global competition to reduce greenhouse gases through scientific innovation.
Imagine a future where concrete is not only carbon neutral but also subtracts carbon from other industries. That’s the closed loop that Carbon Upcycling hopes to create with CO2NCRETE.
“I decided to get involved in this project because it could be a game-changer for climate policy,” said J.R. DeShazo, professor of public policy at the UCLA Luskin School of Public Affairs and director of the UCLA Luskin Center for Innovation, earlier this year. “This technology tackles global climate change, which is one of the biggest challenges that society faces now and will face over the next century.”
CO2NCRETE has the potential to be a very big deal. If only UCLA’s PR team could figure out how we’re supposed to pronounce it…
Is the World Ready for Carbon-Friendly Concrete?
Having no background in engineering, I considered this cement alternative just shy of miraculous. With the developing world developing faster than ever, and the international agenda finally focused on climate action, CO2NCRETE seemed to come along at just the right time. Dr. Sant, who I met with at UCLA’s campus, assured me that there’s nothing miraculous about it.
The Carbon Upcycling team began working on the project in 2014. While they’ve made great strides, Gaurav considers the team still within the infancy of its potential. “It’s a question of time and money and investment and innovation. Of course the scale up is a big challenge,” he added. “Technically, it’s not an issue. The question is, can you do it in an economical fashion?”
Planet Experts: So the mixture for concrete basically involves sand and stone and water and cement. Chemically, is this stuff a new kind of cement?
Dr. Gaurav Sant: What we’re trying to do is replace the part that is the cement and water combination. The cement and the water really give you the adhesive action. At a surface level, [CO2NCRETE] is pretty similar. At an atomic level it’s not. The fundamental building blocks are the same, but it’s a question of do you look at an elephant from 30,000 feet away or do you look at an elephant from five feet away?
PE: Using carbon to make cement seems like a great but off-the-wall idea. Has anything like this been attempted before?
GS: To my understanding, the approach that we’ve taken is completely unique. There’s nothing like it. People have attempted things of a similar fashion. In broad strokes, they came nowhere close in terms of our efficiency to sequester CO2. For one unit of reagent we can do one unit of CO2. There are very few things that can actually take up that level of CO2.
PE: That sounds good.
GS: It’s fantastic. It’s not just good, it’s great.
PE: Thus far you’ve been able to create small cones of concrete using your new process. Is the next stage to build a building with carbon emitted by factories?
GS: We still have a lot of developmental work to do, so I think we’re a long way from either of those two steps. That’s where we want to end up, scaling it up and then taking an integrated process out to a potential client and saying, ‘Well, do you want us to help take care of your carbon dioxide?’
PE: And what about cost?
GS: As I see it, the reaction is the trivial part. Converting this into material that will hold up you can do really cheaply. But, you’re trying to replace something that costs three cents a pound. It’s a great deal if you consider the absence of a penalty for the carbon dioxide. The question is, what is the penalty placed by carbon dioxide? Financially or environmentally? Both of those have different costs. Can you violate the cost structure of what we deal with today, but have something that you can produce at large scale efficiently and fulfills or exceeds the performance what we use already? It’s a pretty tall order.
PE: You’re right. Today that carbon dioxide is negligible to most companies. Externalities like greenhouse gas emissions aren’t factored into costs. But in a post-COP21 world, is there higher demand for carbon-neutral solutions?
GS: Twenty years ago, there were people sitting at tables and having this exact same conversation. What happened? What happened after Kyoto? Nothing happened. That’s my take on it.
I work in a university. That means we’re in the business of creating knowledge and creating solutions. It’s not my mandate to force market uptake. The issues of market dynamics are controlled by more than one thing. Optics is part of it, economics is a part of it, legislation and policy is another part of it. While we can educate and inform some of these directions, we can’t force them. But if you create a solution and there is a need, the market will adopt and adapt.
PE: How optimistic are you about the market recognizing the need?
GS: We’re sort of in a transition of chimpanzees turning into human beings. There were a couple different iterations we went to before we settled into the human beings that we are today. We’re at an evolutionary step and without that nothing else happens.
It seems as though the time is right, that’s what I’ll say. It seems as though this is the right condition of events that might actually make something change.