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  • The Earth's climate is shifting, and it's our fault.

  • Not Seeker, specifically, I mean humans in general.

  • We're digging up and burning sources of carbon that otherwise would have been locked

  • away within the Earth, adding it to our atmosphere and driving average global temperatures up.

  • So why don't we take the carbon from the air, and push it somewhere else?

  • That's the idea behind Negative Emission Technologies, or NETs.

  • They're one possible tool to stop climate change, but they aren't the silver bullet.

  • It's tempting to think that if we develop a way to scrub the air of CO2 we won't have to cut down our emissions so much.

  • No lifestyle change, no big shift in energy infrastructure, just some quick fix that keeps this climate change thing from getting out of hand.

  • Unfortunately while that's theoretically possible it's very far from practical.

  • At the start of 2018 the European Academies Science Advisory Council released a report

  • on how feasible NETs are for slowing or reversing the effects of atmospheric carbon dioxide and their conclusion isnot good.

  • First it helps to understand why plucking CO2 from thin air isn't as easy as it sounds.

  • As of 2013 we were adding an estimated 40 billion tons of CO2 to the air annually.

  • While that's a lot of CO2, it's not very concentrated; there are only about 400 CO2 molecules per million molecules that make up our air.

  • So if you want to just neutralize the stuff we're putting out each year, you're going to have to churn through a lot of air.

  • Jennifer Wilcox, an assistant professor at Stanford University, imagines what she calls a synthetic forest.

  • Sounds like cool funky neon trees but really it's more a 200 meter wall of fans pushing air through liquid with chemicals that capture carbon dioxide.

  • The chemical is then separated from the CO2 using high heat, allowing it to go back and capture more carbon.

  • What's left behind is high-purity CO2 that's easier to liquify or repurpose.

  • Now you may have noticed this process isn't passive, you need to put energy into it.

  • Wilcox estimates that to remove a million tons of CO2 a year,

  • you'd need a dedicated power plant putting out anywhere from 300 to 500 megawatts.

  • So to balance out that 40 billion tons we're emitting annually, that works out to 40,000 additional power plants.

  • And that's assuming you use carbon neutral power.

  • If you use a coal plant, you emit more than you extract.

  • A synthetic forest isn't the only possible negative emission technology.

  • We could go au naturale and plant more forests.

  • Let the trees do the work.

  • Except planting new forests is hard and we're already deforesting what currently exists.

  • Really it'd be better to get that under control first.

  • Another alternative is sprinkling iron into the ocean, stimulating photosynthetic plankton to absorb more CO2.

  • But that process is kind of like unleashing a tiger and hoping it takes care of your gorilla problem.

  • We could try making a carbon capturing mineral like magnesite in a lab.

  • The mineral forms when magnesium is introduced to carbonic acid, a molecule that results when CO2 and water react.

  • In August of 2018 scientists discovered how to make it artificially in just 72 days,

  • as opposed to the hundreds of thousands of years it takes to form naturally.

  • Now we just need to make 80 billion tons of the stuff every year and we're set.

  • All of these issues led the European Academies Science Advisory Council to conclude that betting on NETs alone is not the answer.

  • We can't keep emitting at the rate we are now and hope some future carbon capture wonder tech will turn the tide.

  • The goal is still to cut current emissions as drastically as possible.

  • In the meantime we can still develop negative emission technologies.

  • Just because they can't stop climate change alone doesn't mean they can't help.

  • But humans need to scale back our carbon emission so NETs don't have to counter 40 billion tons of CO2 every year.

  • While you're here subscribe for more videos, and check out Marens video about new solar technology powered by bacteria.

  • While CO2 levels are at 400 parts per million today, until 1950 CO2 hadn't risen above 300 parts per million for over 400 thousand years.

  • Thanks for watching and I'll see you next time on Seeker!

The Earth's climate is shifting, and it's our fault.


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B1 中級

大気中からCO2を回収するのが難しい理由 (Why It's So Hard to Capture CO2 From the Air)

  • 161 7
    Jerry Liu に公開 2021 年 01 月 14 日