A similar article linked at the GRT website from several weeks ago is shown
below. Some material at the website http://www.grtaircapture.com/ has
changed from the last time I looked. The last update is June 22, the same
day as the CNN article.
I agree with a lot of what Lackner says, having investigated the potential
for capture of CO2 from transportation and non power plant residential and
commercial sources (there isn't any for the reasons he states). As for the
business model he is now promoting, it seems to have morphed from air
capture to remove the legacy CO2 to "let's see if we can keep this business
going long enough with sales of CO2 for commercial use until we can get the
government to underwrite the costs of air capture of CO2 that has no
economic value which is almost all of it." No problem with that one either,
especially in today's global economy.
I am somewhat surprised at the claim that the energy costs are now about the
same as those estimated for removal and sequestration of CO2 from pulverized
coal-fired power plants. This implies that the new resin-based system
(actually the resin used in water softeners) removes CO2 at a cost of less
than $300/ton of CO2, about 3-5 times less than previous estimates. A more
detailed side-by-side comparison is needed to convince me. $300/ton is also
too expensive and I would note that the way in which costs for technologies
decrease is not linear. That is, as the process becomes more and more
efficient, the additional efficiency becomes harder and harder to achieve
and at greater cost. Look at photovoltaic as an example.
I also think that from a practical perspective, the CO2 that can be captured
is probably less than 20% of the total, in that not only is it not possible
to capture emissions from mobile sources, homes, businesses and factories
including large industrial plants like petroleum refineries and steel mills,
it probably will not be cost effective to capture CO2 from ANY sources other
than coal-fired and natural gas fired power plants that don't produce a
nearly 100% CO2 gas stream. As none of these exist today and will not exist
in significant numbers for decades (read the latest climate change bill),
CCS cannot contribute to stopping the warming for a long, long time.
I also don't understand the comparison between the wind turbine and the air
capture collector. They are designed for different purposes.
Broecker also understates the magnitude of the scale of the number of units
and the requisite time required to lower the atmospheric CO2 level.
Remember that we are dealing with the "debt here," not the increase in the
"debt," to make an economic comparison. To stabilize the atmospheric CO2
level would require the removal of about 15 billion tons of CO2 per year,
that number increasing to 20 in a few decades if not sooner. Lowering the
level would require removal of even greater quantities, unless human
emissions are decreased from present day. But even a stabilization of
emissions over the next 20-50 years (quite an accomplishment when you
consider what we are facing) will not be enough. However, as part of a
portfolio that includes source mitigation, energy efficiency, SRM and other
other geo technologies along with policy mechanisms (taxes, cap and trade,
treaties), air capture may be able to play a significant role in this
century, but not for decades.
The final statement that Lackner makes in the NYT article that the air
emitted from the collector has the pre-industrial level of CO2 is unclear to
me also. The air emitted should have close to 0 ppmv CO2 and the air next
to the collector about that from 2009 as the air mixes very quickly close to
the ground. The real problem with this and other systems proposed for the
same purpose is not the danger of altering the atmospheric CO2 level. It's
that due to the magnitude of the problem and the time scales, it won't in
time. Still, I think this should be a MAJOR research area for DOE and other
government energy agencies. The fact that only a handful of people are
working on this now (GRT isn't hiring and I thought they closed down last
year for a time) will make the development of practical scalable systems
that much more unlikely. That's probably why there are geoengineering
groups and not air capture groups.
http://www.cnn.com/2009/TECH/science/06/22/synthetic.tree.climate.cha...
'Synthetic tree' claims to catch carbon in the air
a.. Story Highlights
b.. "Synthetic tree" would capture carbon dioxide in the air to reduce
emissions
c.. Trapped carbon would be compressed to liquid CO2 ready for
sequestration
d.. Technology is being developed by scientists at Columbia University in
the U.S.
e.. Broecker: "I think this is something that the world's going to have to
have"
updated 3:37 p.m. EDT, Mon June 22, 2009
By Hilary Whiteman
CNN
LONDON, England (CNN) -- Scientists in the United States are developing a
"synthetic tree" capable of collecting carbon around 1,000 times faster than
the real thing.
A conceptual design of how the "synthetic tree" might look should they ever
reach the stage of production.
As the wind blows though plastic "leaves," the carbon is trapped in a
chamber, compressed and stored as liquid carbon dioxide.
The technology is similar to that used to capture carbon from flue stacks at
coal-fired power plants, but the difference is that the "synthetic tree" can
catch carbon anytime, anywhere.
"Half of your emissions come from small, distributed sources where
collection at the site is either impossible or impractical," said Professor
Klaus Lackner, Ewing-Worzel Professor of Geophysics in the Department of
Earth and Environmental Engineering at Columbia University.
"We aim for applications like gasoline in cars or jet fuel in airplanes. We
are going after CO2 that otherwise is nearly impossible to collect," he told
CNN.
While the idea of carbon-catchers may sound far-fetched, an early model has
been built and Lackner is in the process of writing a proposal for
consideration by the U.S. Department of Energy.
He personally explained the concept in a 45-minute meeting with U.S. Energy
Secretary Steven Chu last month at a three-day symposium on climate change
in London.
"He was there and I was there and he showed interest," Lackner told CNN.
"That's exciting, but I don't particularly want to discuss this in a public
forum because I think this gives me a little bit of an opportunity to tailor
my proposals to the Department of Energy in a way that makes them more
palatable."
Lackner started working on the concept of an ambient carbon catcher in 1998.
"I argued back then and I still argue that the reason this can be done, from
a theoretical point of view, is that the CO2 in the air is actually
surprisingly concentrated, therefore the device you need to collect CO2 is
quite small."
The "synthetic tree" looks more like a public convenience block than a
hi-tech method of reducing carbon emissions, but Lackner told CNN it is
highly efficient for its size when compared, for example, to a modern
power-generating wind turbine.
"If you give me one of those big windmills which have those big areas
through which the rotor moves -- how much CO2 can I avoid? And if I had an
equally sized CO2 collector -- how much CO2 can I collect? It turns out the
collector is several hundred times better than the windmill."
Is the "synthetic tree" an interesting alternative, or a scientific flight
of fancy that's unlikely to happen? Sound Off below.
Lackner told CNN that initial concerns over the cost of the technology were
focused on the "front-end" carbon collector, including the sorbent used to
catch the carbon dioxide in the air.
But after years of research, Lackner told CNN he and his colleagues have
developed a sorbent that is "close to the ideal," in that it uses a
relatively small amount of energy to release the CO2 and is not
prohibitively expensive.
"By the time we make liquid CO2 we have spent approximately 50 kilojoules
[of electricity] per mole of CO2." Compare that, Lackner said, to the
average power plant in the U.S. which produces one mole of CO2 with every
230 kilojoules of electricity.
"In other words, if we simply plugged our device in to the power grid to
satisfy its energy needs, for every roughly 1000 kilograms [of carbon
dioxide] we collected we would re-emit 200, so 800 we can chalk up as having
been successful," he said.
Lackner told CNN the biggest cost was at the "back-end" of the collector,
primarily the technology used to release the CO2 from the sorbent.
He said for that reason, on a cost-basis, the "synthetic tree" could not
compete with modern coal-fired power plants that are designed to release
fewer carbon emissions than their older predecessors. But he said when
compared to the cost of retro-fitting an existing coal plant, the "synthetic
tree" becomes more viable.
"The bottom line is we have in this way the ability to deal with the problem
at a cost which is somewhat higher than on a coal-fired power plant
retro-fit, but not much higher."
Besides, he said, the technology is not being developed as an alternative to
the carbon capture and storage methods currently being tested for
large-scale use on coal-fired power stations. He's targeting carbon that's
already in the air.
The concept of the "synethic tree" has caught the imagination of one of the
first scientists to warn the world about global warming, Lackner's colleague
at Columbia University, Newberry Professor of Earth and Environmental
Sciences, Professor Wally Broecker.
"I'm extremely excited about this. I think this is something that the
world's going to have to have, unfortunately," Broecker told CNN from Madrid
where he received a BBVA Foundation Frontiers of Knowledge Award for his
work on the issue of climate change.
Broecker
...
read more »
|
