I am a fan of Ted Talks; I have listened to a lot of them and about very diverse topics. Recently I found one that really caught my eye: How we could make carbon-negative concrete, by Tom Schuler. In this six-minute podcast, the president and CEO of Solidia, explains what he and his team have been working into since 2007.
Everything starts with cement, the main ingredient in concrete. Concrete is the second most used material in the world, just after water. For every metric ton of cement produced, there’s an equal amount of CO2 that’s released into the atmosphere. Every year, more than 4 billion metric tons of cement are produced, that is the 8% of global carbon dioxide emissions.
Since 2007, people at Solidia have been trying to cut down that CO2 emission. the most used cement nowadays is the Portland cement. In order to make it, limestone and sand are mixed in a relation of 2/3 and 1/3 and they are heated at 1500ºC so they can react. At Solidia, they have changed the formula to a relationship of 50/50 and this mixture reacts at a lower temperature, around 1200ºC. This means that for every ton of cement, 40% less of CO2 is emitted and 30% of energy is saved compared to the traditional way. So not only do we pollute less, but also more cement is produced with the same amount of energy. In addition to that, they also save CO2 in the curing process. They inject it in the machines where cement hardens, and it is trapped in the cement blocks. This adds up to a 50/70% of CO2 saved in the whole process depending on the formula. Furthermore, in this process less water is required, thus making it suitable for areas that are struggling with drought problems. It seems to me that green cement is a really smart choice, so it shocked me that less than 5% of the cement used in the world is green.
One of the main obstacles of this green cement is its format, right now, the most used right now is ready-mix cement and the Solidia one is only available in blocks. Another big drawback is the fact that cement has been produced for over 2000 years and the formula has changed very little, so the industry is quite reluctant to change. For this reason, they have their products tested by third parties.
This reminded me of José Polo, whom I met during the field practice, he said that the main problem of architects was that they are not willing to incorporate new methods to their projects, that they are really attached to the techniques that have been used for years. I would really like it if the construction industry proved him wrong (in the good sense of course), I want to believe that the companies are seeking for alternatives that pollute less and that we are all willing to get out of our comfort zone and give a chance to new products.
I found this company extremely interesting because they are not planning on producing cement, they just want to help companies make their own eco-friendlier because. As they say, there is already a lot of companies that make concrete, but there are very little that make green concrete and if only they started changing to green on eventually, the carbon emissions would go down drastically.
I watched a short video where they explained everything: https://www.cnbc.com/video/2019/09/28/solidias-cement-locks-in-co2-instead-of-releasing-it-into-the-air.html
And here’s the link to the podcast where I first heard of this: https://open.spotify.com/episode/6BrORNsAVHDDBPdZv9xi14?si=m_mfb0KyRHWjVp8jolw9Iw