What if we could trap carbon dioxide before our power plants pump it into the atmosphere?

It’s a neat idea, and it can work. But current carbon capture technology is expensive and less helpful than we’d like.

So researchers have started looking for better materials to capture all that CO2. And that search has led them to the very atoms that got us into this mess in the first place: Carbon itself. [♪ INTRO] Now, really, the whole world needs to reduce our energy consumption and change where our energy comes from to slow down climate change. But we’re not doing either of those things -- at least not worldwide.

Eighty percent of the world’s energy comes from fossil fuels, and it has for decades. And we keep using more energy per person, not less. So we need to get our act together.

But carbon capture technology could be the bridge we need until we get there. Some techniques, like direct air capture, pull carbon dioxide out of the general atmosphere. But that means the gas has time to spread out.

And since it’s less concentrated, it takes more time, energy, and money to suck it all up. Meanwhile, there are also ways to remove carbon before burning your fossil fuel of choice, but incorporating this tech into a power plant pretty much means rebuilding the plant from scratch. So instead, a lot of carbon capture happens right in-between: after burning the fuel, but before carbon dioxide enters the atmosphere.

Even that can be harder and more expensive than it might sound: Electricity from a power plant with carbon capture can cost anywhere from 20 to 90 percent more than it would have otherwise. That money goes into powering and running the carbon-capture facility, which collects all the CO2, as well as the infrastructure that ships it out and shoves it somewhere underground where it won’t escape into the atmosphere. Today, one common way to trap carbon dioxide is with a type of liquid called an amine-based solvent that reacts strongly with CO2 but doesn’t react to much else in the exhaust.

Once exhaust has been treated and then passed through the liquid, eighty-five or ninety percent of the CO2 in the original exhaust has reacted with the amine solvent and become trapped. Then, the liquid gets heated up and the reaction reverses, releasing CO2 into a new container. From there, it’s pretty straightforward to collect all that gas and squeeze it down underground, and then reuse the solvent for the next batch of exhaust.

But with every round, a little solvent naturally breaks down into some pretty hazardous stuff. Heating it up to get the CO2 out also takes a ton of energy. And when you account for the production of that energy, carbon capture might only prevent about half of a power plant’s total emissions, even if the carbon capture is powered by a renewable source like wind!

Which isn’t nothing, but it’s not enough to get us over the hump from fossil fuels to renewables. So researchers are searching for alternatives: A new material that grabs carbon dioxide out of exhaust and holds it tightly, but still releases it without putting in too much work. It needs to be reactive, but not too reactive.

It needs to be cheap, but hardy. It needs a lot of space where reactions can happen without being big and bulky and hard to move around. That’s a pretty specific set of needs, and no one has a perfect alternative to amines yet.

But a lot of recent research has focused on a surprising contender: Carbon itself. One option is activated carbon, where something organic like wood or shells is heated and treated in a particular way so that its carbon atoms form many layers with lots of tiny holes. All those layers and holes give activated carbon a huge surface area: A single gram of activated carbon might have the same amount of surface as three entire basketball courts.

So there are countless little areas for carbon dioxide to bond as exhaust goes by. And just like with current solvents, the CO2 falls right out when the activated carbon is heated up. Activated carbon made from certain kinds of sawdust might capture 97% of carbon dioxide in exhaust.

That’s even better than the solvents. Plus, there are other activated carbon compounds that only require about half the energy amines need to release the carbon dioxide they’ve slurped up. If researchers could find one source of carbon that does both at the same time and comes from a sustainable source and isn’t too expensive, we’d really be in business.

But one problem with trying to find a suitable carbon compound is the same thing that makes carbon so amazing for life in the first place: There are just so many ways of organizing and bonding carbon to itself and other atoms, and little differences in structure lead to some huge differences in ability. Some researchers are studying graphene, the nearly magic material with all of the good properties, made of carbon in atom-thick sheets. Whether graphene’s string of successes will someday include carbon capture is still to be seen, though.

Others are looking at nanotubes, where graphene is wrapped into a pipe. And others are looking at nanotubes with smaller nanotubes inside them. It’s a huge arena of possibilities.

But many of these lines of research are still stuck in the same general model that we use for amines: Adsorb carbon dioxide at a low temperature and release it at a high temperature. A few, though, are trying something different. They have electric circuits with activated carbon or carbon nanotubes.

Either way, carbon dioxide can be trapped as long as a current flows. As soon as the current stops, the bonds break. Of course, that electricity has to come from somewhere.

Nothing comes for free. But running these systems doesn’t take any more energy than most of the other leading carbon capture candidates. And they might come out even better once you account for all the processing that has to happen with other kinds of carbon capture.

For now, no form of carbon capture is perfect. But we have to start somewhere. Because we’re not just looking to decarbonize energy production.

Plenty of industries can release carbon into the environment whether their machines are powered by coal or wind. So if we can’t jump straight to a sustainably green future, capturing the carbon we emit with the carbon we don’t is a pretty good place to start. Thanks for watching this episode of SciShow.

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