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Archive for the tag “CO2 Visualization”

Imaging CO2: An interview with laser imager Vic Miller

laser car imaging

No one has yet captured an image of the CO2 spewing from car tailpipes.  As discussed in my last post, such video images could revolutionize how we think about the copious carbon pollution (20 lbs. of CO2/gallon) we emit when we drive.

To better understand how and when we might expect to get images of CO2 tailpipe emissions, I interviewed Vic Miller, an engineering post-doc at Stanford University, and an expert in laser imaging of gases. Vic is working on a technique to image CO2 from a tailpipe (among other projects).  His team’s laser-enhanced video of a match strike was recently featured in the New York Times.

Vic Miller

Vic Miller

Q. Why has CO2 imaging been so elusive?  What are the principal technical obstacles?

A.   CO2 is an infrared active molecule, meaning it absorbs (and emits) light in the infrared (IR).  And so I’m pretty sure qualitative measurements or images of CO2 emissions can be made with currently available off-the-shelf infrared cameras that are sensitive in the mid-infrared.  The tricky part is being quantitative – or getting an actual measurement of CO2 concentration with well-characterized uncertainty bounds.  This is what the NASA OCO-2 satellite does – it’s a quantitate instrument for measuring CO2 concentration.  The challenges lie in CO2 spectroscopy (i.e., understanding how CO2 absorbs light in the infrared, and what other species also absorb in the infrared and how they could interfere with CO2 spectroscopy) – and there are engineering challenges with making good measurements (is the signal on your detector actually what you think it is?).

Q.  What are the promising new techniques/technology for imaging?

A.  New infrared light sources (e.g., lasers) and infrared detectors are constantly being improved – these new pieces will provide access to better wavelengths (i.e., wavelengths that provide a more sensitive measurement with less interference) for CO2 detection.

Q.  Is it possible to measure it with non-visual means to model how CO2 would move out of a tailpipe?

A.  CO2 measurements can be made relatively cheaply with a capnograph.  CO2 measurements are readily made in medicine to monitor patients’ respiratory health (and other conditions) – the same thing could be done near a tailpipe. Computational fluid dynamics (CFD) could be used to model and observe tailpipe emissions.

Q. When do you think the new imaging techniques might be ready for providing car tailpipe images?

A.  We might be able to have a short little paper out in maybe a year – would like to do it in 6 months, but we probably won’t finish it that quickly.

CO2 Imaging Key to Changing Consciousness

CO2 Black Bag behind car croppedIf CO2 came out of the tailpipe dark and smelly, strict controls on emitting it would probably have been in effect long ago.  Instead, CO2 is invisible and odorless.  We exhale it with every breath.   Most of us are unaware that our cars spew vast quantities of it.

In a society in which visual image is paramount, how can we show people the vast quantities of CO2 comes out of their tailpipe?  How can the invisible be made visible?

Much of the effort to visualize carbon has been at the macro scale, showing computer models of CO2 emissions at the planetary and state level.  NASA recently released a video modeling CO2 as it swirls through the planetary atmosphere.

NASA Carbon Planet Cropped

Red on map shows high concentration of CO2

Blue Carbon Balls Cropped

Carbon visual’s image of one metric ton of CO2.

Others have also created simple, powerful visual models of CO2 pollution.Carbon visuals, a UK company specializing in producing images and videos of CO2 emissions, uses giant blue balls to show the actual volumes of CO2 being emitted by  automobiles.  The blue ball in the photo represents 1 metric  ton of CO2, or the volume produced by the average US driver in about 2 months of driving.   New York City produces 54,000,000 balls in a year.

All of the above images are models, not actual visual images of CO2.   Imaging CO2 has been extremely difficult because of the properties of CO2’s  electronic transitions.  Researchers are presently working on using lasers in the infrared spectrum to excite CO2 molecules so that they can be imaged.

The successful imaging of CO2 spewing from a tailpipe could lead to an important breakthrough in human understanding and consciousness, similar to the breakthroughs resulting from the first film of a horse running or the first images of Earth from the moon.

The representation of CO2 need not be left only to scientists.   Visual artists, actors, and poets can make the invisible visible, the unreal real, and the unimportant urgent.

Our ability to reduce CO2 emissions rests largely on our grasp of our personal role in the CO2 crisis, and our resolve to minimize our contribution to the problem.  Our grasp and our resolve depend in large part upon our ability to see and communicate visually the CO2 we and others emit.

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