Can Our Streets Absorb Greenhouse Gases?

I wrote about driving to work before, wondering if we could cut emissions with sustainable fuels. Now I’m wondering – what about the roads we drive on?

From streets to buildings, concrete is the most widely used material in the world. Concrete is made from sand, crushed rocks, and water and is glued together with cement. Unfortunately, cement factories are some of the largest emitters of greenhouse gases. The emissions come from decarbonizing limestone and the very high temperatures needed to manufacture cement.

Manufacturing a single ton of cement requires the equivalent energy of burning four hundred pounds of coal

Paul Hawken https://www.drawdown.org/solutions/materials/alternative-cement

So, how can we design a more sustainable version of concrete? Imagine a high-tech skyline with remarkable towers and shopping centers. And heat, a lot of heat. This week we are covering an invention from Abu Dhabi in the United Arab Emirates.

Kemal Celik, an assistant professor at NYU Abu Dhabi, researches how to make sustainable cement. He explores using by-products from other industries. Basically, making cement from recycled materials.

There are a lot of desalination plants in the United Arab Emirates to produce drinking water from seawater. A by-product of the desalination process is residual brine. Kemal figured out a way to make cement with the leftover brine. This is how it works:

His invention, reactive magnesium oxide cement, is produced at much lower temperatures than traditional cement. And the best thing? It actually absorbs carbon dioxide during the hardening process and long after it has been mixed into the concrete, making it carbon negative.

Roads and buildings made with it could actually absorb carbon dioxide from the atmosphere over the years and help combat climate change

Kemal Celik, https://nyuad.nyu.edu/en/research/impact/our-research/2018/just-add-salt.html

Another inspiring innovation. Let’s hope we can all drive on roads made from sustainable concrete sometime soon.

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Can I Drive to Work on Recycled Fuel?

How cool would it be if cars and airplanes could run on gas that has been made from carbon dioxide?

Part 1 of my story about Carbon Engineering covered how they capture carbon dioxide out of the air and turn it into calcium carbonate pellets. This is part two, it covers how they turn the carbon dioxide that they extract into fuel that could be used by cars or airplanes.

Turning air to fuel
Turning Air to Fuel

So, here is how it works. Carbon dioxide from the air is turned into calcium carbonate pellets. These are heated up to reach a much more concentrated form of carbon dioxide. This reacts with hydrogen and energy and is turned into hydro carbon fuels, such as gasoline, diesel or jet fuel.

This technology enables the production of synthetic transportation fuels using only atmospheric CO₂ and hydrogen split from water, and powered by clean electricity

https://carbonengineering.com/about-a2f/

Carbon Engineering designed a closed cycle of turning carbon dioxide from the atmosphere into concentrated carbon dioxide and then into fuel. By utilizing as little water as possible and renewable energy for the process, they are creating a green fuel.

This technology forms an important complement to electric vehicles in the quest to deliver carbon-neutral 21st century transportation.

https://carbonengineering.com/about-a2f/

The BBC has an interesting article about Carbon Engineering’s technology. It also covers concerns from environmentalists that carbon capture could be used as an excuse to prolong the fossil fuel era or prevent us from reducing emissions in the first place.

I think we need to work on reduction emissions as well as capturing carbon. I would love to rely on natural ways such as restoring forests and wetlands only, but it looks like that might not be enough. Carbon Engineering’s technology certainly looks promising.

What I like most about it is the idea of tuning the extracted carbon dioxide into a valuable product. If there is monetary incentive for carbon capture this technology might get adopted more broadly.

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