This episode is sponsored by Wren, a website with a monthly subscription that helps fund projects to combat the climate crisis.

Click on the link in the description to learn more about how you can make a monthly contribution to support projects like rainforest protection programs. [♪ INTRO] With the climate crisis already causing big problems, scientists are creating new high-tech solutions that can capture and reuse carbon dioxide. Even better: these new technologies are focused on creating a circular carbon economy.

That’s where the carbon dioxide that’s emitted during a process, like manufacturing a shirt or flying a plane, is recaptured from the atmosphere and then reused as energy to fuel that process again. The goal is to create a carbon-neutral loop, where all of the CO2 that’s emitted gets captured and put back into the system! Which is, you know, a lot more sustainable than most of what we’re doing right now.

A circular carbon economy starts with capturing CO2. And for this, we can turn to an unlikely partner: algae! Scientists have been experimenting with using algae to capture carbon for decades.

That’s because it is great at removing CO2 from the atmosphere. In fact, 1 kilogram of algae can absorb about 1.8 kilograms of carbon dioxide. But using algae for carbon capture, or sequestration, has been tricky.

In the past, algae sequestration has needed lots of land and water to work, and it’s required lots of maintenance too. A study published in 2021 developed a more efficient way to use algae to capture CO2 by making biocomposites. Biocomposites are made by combining one natural and one synthetic material to produce a new, better material; in this case, literally a carbon-capturing sheet.

Researchers used the microalgae Chlorella vulgaris and coated textiles with it to make a biocomposite. Cotton and polyester, to be exact. The fabric gave the algae something to anchor to, so they grow more efficiently and take up more CO2.

These biocomposites were tested with a mixture of CO2 and air to measure how well they could absorb CO2. The researchers found that their new biocomposites absorbed 3.5 to 14.5 times more CO2 than the control algae that wasn’t grown on fabric. Even better: the researchers found that their algae-textile biocomposites used less water and were lower maintenance.

And they’re also hopeful that these biocomposites may help solve another environmental problem as well. Every year, more than 110 million tons of textiles are made… and only 15% of those are recycled. They want to turn some of that waste into biocomposites, so we can keep textiles out of landfills by transforming them into slimy carbon catchers!

But in order to have a circular carbon economy, we have to do more than just remove CO2 from the atmosphere. We have to transform it into something else, like fuel. Fuels are substances that react with something else, usually oxygen, to release energy that we can harness to power something like a jet engine.

CO2 is not a fuel, but it does contain the key element that makes up the backbone of most of the fuels we use: carbon. The problem? You have to put energy in to be able to get it back out!

One major target for reducing emissions is air travel, and the fuel that planes depend on. Jet fuel and gasoline are similar, but they’re not identical. Both are derived from petroleum, but they’re made up of differently sized molecules.

Where gasoline’s molecules typically have 7 to 11 carbon atoms, jet fuel has 12 to 15. And although jet fuel is not more polluting than gasoline, the amount of fuel that’s burned during a flight adds up. A round-trip flight from London to San Francisco emits 879 kilograms of carbon dioxide.

To put that into perspective, the CO2 generated by that flight is equal to about 22 percent of the average person’s annual CO2 emissions. That’s a big deal, especially since the Environmental and Energy Study Institute estimates that the emissions from passenger air travel could triple by 2050. So figuring out how to recycle the CO2 generated by planes can make a big dent in emissions.

In 2020, researchers developed a process that took carbon dioxide molecules and turned them directly into jet fuel. They did this using a special metal-based catalyst, a substance that lowers the energy barrier for a chemical reaction to get going and speeds everything up. Catalysts can be a huge variety of kinds of substances.

The only rule here is that they are not used up in the reaction they facilitate, so a small amount can go a long way. In this case, the catalyst was made from iron, manganese, and potassium to drive the chemical reaction. To start, scientists infused a stainless steel reactor with carbon dioxide.

From there, the researchers added the metal catalyst and 350 degrees of heat…and voila! They produced fuel with a similar number of carbon atoms as jet fuel, suitable for airplane engines. So if we can reclaim the CO2 emitted by airplanes and turn it back into airplane fuel… we could theoretically create a circular carbon economy around air travel.

And make vacations a little more guilt-free in the process. But there are things that we already make with CO2 that can become a part of a circular carbon economy. Urea is an essential component of fertilizer, providing plants the nitrogen they need to grow healthy leaves and stems.

To make urea, manufacturers use a chemical reaction of ammonia and carbon dioxide, and then they heat the resulting compound to form urea. Traditional methods of making urea consume more than two percent of the world’s energy and release a lot of harmful byproducts. It’s the energy problem once again: to make CO2 react to do much of anything, you have to give it a push.

But a study published in 2020 proposed a new way to produce urea that reuses CO2. To do this, the researchers started with a flow reactor cell, which can conduct electricity from the chemical reaction that happens inside it. From there, they loaded the flow reactor cell with a catalyst (a different one this time).

This one’s made of palladium-copper nanoparticles attached to titanium dioxide nanosheets. With the help of the catalyst, the CO2 and nitrogen reacted to produce urea in a single step using a lot less energy, equipment, and space than traditional methods. Since we’re using CO2 to make fertilizer anyway, using the same carbon dioxide that’s released from the urea to make more urea can help us close the loop and make fertilizing crops carbon neutral.

Especially if the whole process is fueled by renewable energy! And while this technology is new, the researchers want to streamline it so that small farmers around the world can manufacture urea themselves. Which would be good news for farmers… and for Mother Nature.

We know that we need to reduce our CO2 emissions to deal with the climate crisis. And one way to do that is by recycling the CO2 we’ve already released by transforming it into stuff that we are already using, like jet fuel and urea… …or taking old stuff and using it to capture CO2, like with recycled fabric biocomposites. By figuring out how to use the CO2 we’ve already made, we can start taking baby steps toward becoming truly carbon neutral.

And when it comes to climate change, every single thing we do to make it better makes it better. This SciShow video is supported by Wren, a subscription service to fight the climate crisis every month. When you’re just beginning your personal battle against climate change, it can be hard to know where to start.

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With Wren, you’re not just signing up with the hope that someone somewhere is doing something good for the planet with your money. They will send you monthly updates from the tree planting, rainforest protection, and carbon removal projects you support. Over the long term we need governments to fund these projects, but we can start by crowdfunding them.

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