..........................................................................................................................................................................................................................................................................................................
Tailpipes That
Capture CO2
Can we make
tailpipes that capture CO2?
If we're dependent on oil but concerned about
carbon dioxide emissions, why don't we just capture the CO2 we emit? Researchers
are looking into this right now. The result is aminosilica, a powdery substance
that looks like white sand. Within the substance, a number of branches that
resemble trees are born from the bonding, hence the name: hyperbranched. At the
branches' tips are amino sites that capture CO2. When HAS was combined with
sand, the chemists found that the resulting compound was capable of trapping
carbon dioxide when flue gasses -- emissions found in smokestacks -- passed
through it. The HAS compound not only captures CO2, it hangs onto it. To release
the carbon dioxide, the material must be heated, and the CO2 that's released
can be captured and stored (either as a gas or cooled into liquid form) in a
process called carbon sequestration.
BY JOSH CLARK
Environmental Issues Smog over Beijing, China, in May 2008. The nation is the largest emitter of carbon dioxide; the United States is a close second. |
Around
the world, people are growing increasingly concerned about carbon dioxide (CO2)
emissions.
Certainly,
climate change skeptics pose reasonable hypotheses that suggest changes in
climate are merely a natural, global cycle -- and we humans are just going to
have to ride out.
But
the idea that humans are contributing to climate change is becoming more
accepted.
In
response, scientists are thinking of ways to reduce humans' greenhouse gas
(GHG) emissions.
One
way is to create fuels that don't produce carbon dioxide as a byproduct, like
fossil fuels do.
Biofuels
like cellulosic ethanol made from corn or switchgrass still emit CO2 when
burned for energy, but in far smaller amounts -- as much as 85 percent less.
Burning
hydrogen to power a car produces no carbon dioxide; the only byproduct is
water.
And
electricity produced from renewable resources like wind or solar power doesn't
produce any emissions at all.
The
problem with these technologies is that they're still being developed.
Researchers
are facing obstacles like cost and net energy ratio -- input of energy versus
energy output -- that make oil more attractive than alternative fuel sources.
This
is significant, because our world is powered by oil.
From
the airplanes that make travel possible, to the trucks that transport food and
the power plants that produce our electricity, oil dominates the global
economy.
It's
a pretty good question: If we're dependent on oil but concerned about carbon
dioxide emissions, why don't we just capture the CO2 we emit?
Actually,
researchers are looking into this right now.
Professor Chris Jones at the Georgia Institute of Technology (Georgia Tech) and his team have come up with a material called hyperbranched aminosilica (HAS) that captures and stores carbon dioxide emissions.
So,
will we soon find tailpipes on cars made of HAS, and what exactly is this
material anyway? Find out on the next page.
Hyperbranched Aminosilica
Georgia Tech graduate student Jeffrey Drese displays a tubular reactor filled with the HAS adsorbent dispersed in sand. |
So,
will our cars' tailpipes be made of this stuff called hyperbranched aminosilica
(HAS) in the near future?
Dr.
Chris Jones says he doesn't think so; storing captured carbon from all those
tailpipes would be too costly.
Instead,
Jones and his team at the Georgia Institute of Technology (Georgia Tech) are
focused on an even bigger source of carbon dioxide emissions -- power plants.
You
may think of electricity as clean energy. But have you ever considered where
electricity comes from?
Since
it's an energy carrier, electricity gets its energy from another source.
In
the United States the majority of that energy -- 50 percent -- comes from coal.
Electrical
power plants worldwide use enough fossil fuels for energy production to account
for 26 percent of global CO2 emissions; transportation (including planes,
trains and automobiles) account for 13 percent worldwide.
Jones
has his sights set on cleaning up smokestacks. HAS can help by adsorbing CO2.
The
Georgia Tech researchers used covalent bonding (combining two molecules by
joining their electrons) to bind amines -- nitrogen-based organic compounds --
with silica (quartz).
The
result is aminosilica, a powdery substance that looks like white sand.
Within
the substance, a number of branches that resemble trees are born from the
bonding, hence the name: hyperbranched.
At
the branches' tips are amino sites that capture CO2.
When
HAS was combined with sand, the chemists found that the resulting compound was
capable of trapping carbon dioxide when flue gasses -- emissions found in
smokestacks -- passed through it.
The
HAS compound not only captures CO2, it hangs onto it.
To
release the carbon dioxide, the material must be heated, and the CO2 that's
released can be captured and stored (either as a gas or cooled into liquid
form) in a process called carbon sequestration.
This
is actually more exciting than it sounds. Not only will it reduce CO2
emissions, it makes it possible to reuse the captured CO2 to feed biofuel
stock.
One
company grows algae in Louisiana for use as a biofuel. The algae are fed with
captured CO2.
Hyperbranched
aminosilica has some advantages over other methods of carbon sequestration.
For
one, it's recyclable. HAS can be used over and over again; the Georgia Tech
researchers tested one batch 12 times and found that there was no noticeable
decrease in adsorption.
And
the material also isn't affected by moisture, which is a plus since water vapor
is present in flue gases.
It's
also low on required energy input; the only energy needed comes from the
generation of the heat that releases the CO2.
But
there are some challenges that face the project. For one, the CO2/amine
reaction that binds the carbon dioxide to the branches generates heat.
The
researchers found that the aminosilica captures CO2 best at cool temperatures,
so they must figure out how to get rid of the heat that's produced quickly, so
the CO2 binds.
Another
problem is exactly how to apply the compound. Can it be packed into smoke
stacks?
Can
the material be produced into removable discs that cover smoke stack openings?
Although HAS may never be found in tailpipes, if the Georgia Tech researchers can lower carbon dioxide emissions from energy production alone, they will have offered one new way to solve our greenhouse gas troubles.
Josh Clark wanted to be a professional writer
since his third-grade teacher told him a short story he wrote was kind of good.
He's written ever since. He's a former senior writer for HowStuffWorks and
current co-host of the Stuff
You Should Know podcast. Josh lives with his wife, Umi. The pair really,
really enjoys traveling, solving mysteries, having pizza parties and visiting
museums (both renowned and obscure). Josh has been to the real-life house that
served as the Robin's Nest on "Magnum, P.I." and is on an indefinite
hiatus from being a jerk.
https://auto.howstuffworks.com/tailpipe-capture-co2.htm
You might also like:
Biogas
CLICK HERE . . . to view . . .
https://puricare.blogspot.com/2020/03/biogas-biogas-is-mostly-methane-ch4-and.html
.............................................................................................................................................................................................................................................................................................pie
No comments:
Post a Comment