[The U.S. Department of Energy has an ambitious goal to scale up
direct air capture, a technology that uses chemical reactions to
capture CO2 from air. We asked a pioneer about the state of the
technology and where it’s headed.] [[link removed]]

THESE 'TREES' SCRUB GREENHOUSE GASES FROM THE AIR  
[[link removed]]


 

Klaus Lackner
January 18, 2022
The Conversation
[[link removed]]


*
[[link removed]]
*
[[link removed]]
*
* [[link removed]]

_ The U.S. Department of Energy has an ambitious goal to scale up
direct air capture, a technology that uses chemical reactions to
capture CO2 from air. We asked a pioneer about the state of the
technology and where it’s headed. _

One ‘mechanical tree’ is about 1,000 times faster at removing
carbon dioxide from air than a natural tree. The first is to start
operating in Arizona in 2022, Credit: Arizona State University

 

_Two centuries of burning fossil fuels has put more carbon dioxide, a
powerful greenhouse gas, into the atmosphere than nature can remove.
As that CO2 builds up, it traps excess heat
[[link removed]]
near Earth’s surface, causing global warming. There is so much CO2
in the atmosphere now that most scenarios show ending emissions alone
won’t be enough [[link removed]] to stabilize
the climate – humanity will also have to remove CO2 from the air._

_The U.S. Department of Energy has a new goal
[[link removed]]
to scale up direct air capture
[[link removed]], a technology that
uses chemical reactions to capture CO2 from air
[[link removed]]. While federal funding for
carbon capture often draws criticism because some people see it as an
excuse for fossil fuel use to continue, carbon removal in some form
will likely still be necessary
[[link removed]], IPCC reports show. Technology
to remove carbon mechanically is in development and operating at a
very small scale [[link removed]], in
part because current methods are prohibitively expensive and energy
intensive. But new techniques
[[link removed]]
are being tested this year that could help lower the energy demand and
cost._

_We asked Arizona State University Professor Klaus Lackner
[[link removed]],
a pioneer in direct air capture and carbon storage, about the state of
the technology and where it’s headed._

What is direct carbon removal and why is it considered necessary?

When I got interested in carbon management in the early 1990s, what
drove me was the observation that carbon piles up in the environment.
It takes nature thousands of years to remove that CO2
[[link removed]], and we’re on a
trajectory toward much higher CO2
[[link removed]] concentrations,
well beyond anything humans have experienced.

Humanity can’t afford to have increasing amounts of excess carbon
floating around in the environment, so we have to get it back out.

Not all emissions are from large sources, like power plants or
factories
[[link removed]],
where we can capture CO2 as it comes out. So we need to deal with the
other half of emissions – from cars, planes, taking a hot shower
while your gas furnace is putting out CO2. That means pulling CO2 out
of the air.

[[link removed]]

How direct air capture works.

Since CO2 mixes quickly in the air, it doesn’t matter where in the
world the CO2 is removed – the removal has the same impact. So we
can place direct air capture technology right where we plan to use or
store the CO2.

The method of storage is also important. Storing CO2 for just 60 years
or 100 years isn’t good enough. If 100 years from now all that
carbon is back in the environment, all we did was take care of
ourselves, and our grandkids have to figure it out again. In the
meantime, the world’s energy consumption is growing at about 2% per
year
[[link removed]].

One of the complaints about direct air capture, in addition to the
cost, is that it’s energy intensive. Can that energy use be reduced?

Two large energy uses in direct air capture are running fans to draw
in air and then heating to extract the CO2. There are ways to reduce
energy demand for both.

For example, we stumbled into a material that attracts CO2 when it’s
dry and releases it when wet. We realized we could expose that
material to wind and it would load up with CO2. Then we could make it
wet and it would release the CO2
[[link removed]] in
a way that requires far less energy than other systems. Adding heat
created from renewable energy raises the CO2 pressure even higher, so
we have a CO2 gas mixed with water vapor from which we can collect
pure CO2.

[Two men stand beneath a large structure with fans]

Climeworks, a Swiss company, has 15 plants removing carbon dioxide
from the air. Climeworks [[link removed]]

We can save even more energy if the capture is passive – it isn’t
necessary to have fans blowing the air around; the air moves on its
own.

My lab is creating a method to do this, called mechanical trees
[[link removed]].
They’re tall vertical columns of discs coated with a chemical resin,
about 5 feet in diameter, with the discs about 2 inches apart, like a
stack of records. As the air blows through, the surfaces of the discs
absorb CO2. After 20 minutes or so, the discs are full, and they sink
into a barrel below. We send in water and steam to release the CO2
into a closed environment, and now we have a low-pressure mixture of
water vapor and CO2. We can recover most of the heat that went into
heating up the box, so the amount of energy needed for heating is
quite small.

By using moisture, we can avoid about half the energy consumption and
use renewable energy for the rest. This does require water and dry
air, so it won’t be ideal everywhere, but there are also other
methods.

Can CO2 be safely stored long term, and is there enough of that type
of storage?

I started working on the concept of mineral sequestration in the
1990s, leading a group at Los Alamos. The world can actually put CO2
away permanently by taking advantage of the fact that it’s an acid
and certain rocks are base. When CO2 reacts with minerals that are
rich in calcium, it forms solid carbonates
[[link removed]]. By mineralizing the
CO2 [[link removed]] like this, we can
store [[link removed]] a nearly unlimited amount
of carbon permanently.

For example, there’s lots of basalt – volcanic rock – in Iceland
that reacts with CO2 [[link removed]] and
turns it into solid carbonates within a few months. Iceland could sell
certificates of carbon sequestration to the rest of the world because
it puts CO2 away for the rest of the world.

There are also huge underground reservoirs from oil production in the
Permian Basin in Texas. There are large saline aquifers. In the North
Sea, a kilometer below the ocean floor, the energy company Equinor has
been capturing CO2 from a gas processing plant and storing a million
tons of CO2 a year
[[link removed]]
since 1996, avoiding Norway’s tax on CO2 releases
[[link removed]]. The
amount of underground storage where we can do mineral sequestration is
far larger than we will ever need for CO2. The question is how much
can be converted into proven reserve.

[Lackner is shown behind a device with a leafy plant being used for
testing.]

Klaus Lackner tests direct air capture technologies in his lab.
Arizona State University
[[link removed]]

We can also use direct air capture to close the carbon loop
[[link removed]]
– meaning CO2 is reused, captured and reused again to avoid
producing more. Right now, people use carbon from fossil fuels to
extract energy. You can convert CO2 to synthetic fuels – gasoline,
diesel or kerosene – that have no new carbon in them by mixing the
captured CO2 with green hydrogen
[[link removed]]
created with renewable energy. That fuel can easily ship through
existing pipelines and be stored for years, so you can produce heat
and electricity in Boston on a winter night using energy that was
collected as sunshine in West Texas last summer. A tankful of
“synfuel” doesn’t cost much, and it’s more cost-effective than
a battery.

The Department of Energy set a new goal to slash the costs of carbon
dioxide removal to US$100 per ton and quickly scale it up within a
decade. What has to happen to make that a reality?

DOE is scaring me because they make it sound like the technology is
already ready. After neglecting the technology for 30 years, we
can’t just say there are companies who know how to do it and all we
have to do is push it along. We have to assume this is a nascent
technology.

Climeworks is the largest company doing direct capture commercially,
and it sells CO2 at around $500 to $1,000 per ton
[[link removed]].
That’s too expensive. On the other hand, at $50 per ton, the world
could do it. I think we can get there.

The U.S. consumes about 7 million tons of CO2 a year in merchant CO2
[[link removed]] – think fizzy
drinks, fire extinguishers, grain silos use it to control grain
powder, which is an explosion hazard. The average price is $60-$150.
So below $100 you have a market.

What you really need is a regulatory framework that says we demand CO2
is put away, and then the market will move from capturing kilotons of
CO2 today to capturing gigatons of CO2.

Where do you see this technology going in 10 years?

I see a world that abandons fossil fuels, probably gradually, but has
a mandate to capture and store all the CO2 long term.

Our recommendation is when carbon comes out of the ground, it should
be matched with an equal removal. If you produce 1 ton of carbon
associated with coal, oil or gas, you need to put 1 ton away. It
doesn’t have to be the same ton, but there has to be a certificate
of sequestration
[[link removed]]
that assures it has been put away, and it has to last more than 100
years. If all carbon is certified from the moment it comes out of the
ground, it’s harder to cheat the system.

[_Get the best of The Conversation._ Sign up for our weekly newsletter
[[link removed]].]

A big unknown is how hard industry and society will push to become
carbon neutral. It’s encouraging to see companies like Microsoft
[[link removed]]
and Stripe buying carbon credits
[[link removed]]
and certificates to remove CO2 and willing to pay fairly high prices.

New technology can take a decade or two to penetrate, but if the
economic pull is there, things can go fast. The first commercial jet
was available in 1951. By 1965 they were ubiquitous.[The Conversation]

Klaus Lackner
[[link removed]],
Professor of Engineering and Director of the Center for Negative
Carbon Emissions, _Arizona State University
[[link removed]]_

This article is republished from The Conversation
[[link removed]] under a Creative Commons license. Read
the original article
[[link removed]].

*
[[link removed]]
*
[[link removed]]
*
* [[link removed]]

 

 

 

INTERPRET THE WORLD AND CHANGE IT

 

 

Submit via web [[link removed]]
Submit via email
Frequently asked questions [[link removed]]
Manage subscription [[link removed]]
Visit xxxxxx.org [[link removed]]

Twitter [[link removed]]

Facebook [[link removed]]

 




[link removed]

To unsubscribe, click the following link:
[link removed]