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posted by martyb on Tuesday September 18 2018, @06:02AM   Printer-friendly
from the insert-sappy-comment-here dept.

Climate change is killing our planet. The excess production of carbon dioxide and other greenhouse gasses are filling the atmosphere and warming the Earth faster than natural processes can effectively negate them. Since 1951, the surface temperature has risen by 0.8 degrees C, with no sign of slowing. So now it's time for humans to step in and rectify the problem they created -- by using technology to suck excess CO2 straight from the air.

Direct Air Capture (DAC), is one of a number of (still largely theoretical) methods of collecting and sequestering atmospheric carbon currently being looked at. Despite their varied methods, all of these techniques seek to accomplish the same goal: pull carbon dioxide from the atmosphere and sequester it in a form that will not contribute to the effects of global warming.

[...] Unlike current flue gas capture systems, which can only effectively collect CO2 directly from a factory smokestack where the carbon dioxide is more concentrated, DACs can capture carbon at more diverse and distributed sources. And given that roughly half of annual CO2 emissions come from distributed sources (such as vehicle tailpipes), DACs could have a huge impact on climate change.

DACs generally operate by pushing air past a sorbent chemical which binds with carbon dioxide but allows other molecules to pass unimpeded. For example, one of the earliest sorbents employed was a calcium hydroxide solution, which strongly binds with CO2 to create calcium carbonate. The captured CO2 is then unbound from the sorbent, purified and concentrated for use in industrial applications. Of course this is often easier said than done. With the calcium carbonate method (which is derived from the Kraft process), the material must be separated from the solution, dried, and then carbonized at 700 degrees C.

This however reveals the Achilles heel of DACs: their cost. A 2015 study from the National Academies estimated costs of around $400 to $1,000 per ton of CO2 extracted at that time. With nations needed to collectively pull 5 billion tons of carbon out of the atmosphere, every year until 2050, to remain within the bounds of the Paris Climate Accord, doing so with just DACs would prove economically infeasible. The associated energy costs needed to carry out these chemical processes (estimated at 12 gigajoules of electricity per ton of CO2 captured) would be equally staggering.

"Direct air capture could become a major industry if the technology matures and prices drop dramatically," Professor Chris Field, former co-chair of the Intergovernmental Panel on Climate Change's (IPCC), and Dr Katharine Mach, director of the Stanford Environment Facility, wrote in a 2017 Science article. "Direct air capture might require much less land but entail much higher costs and consumption of a large fraction of global energy production."

-- submitted from IRC


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  • (Score: 2) by Aegis on Tuesday September 18 2018, @10:52PM (1 child)

    by Aegis (6714) on Tuesday September 18 2018, @10:52PM (#736795)

    or roughly 25 trees for every man, woman and child currently living on the earth.

    And that's per year!

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  • (Score: 2) by The Mighty Buzzard on Wednesday September 19 2018, @11:11AM

    by The Mighty Buzzard (18) Subscriber Badge <themightybuzzard@proton.me> on Wednesday September 19 2018, @11:11AM (#736980) Homepage Journal

    Dunno if you're aware of this but trees grow every year.

    --
    My rights don't end where your fear begins.