Friday, July 19, 2019

A (Very) Close Look at Carbon Capture and Storage

I too have heard the siren song of carbon capture and storage.
There are two ways to use carbon once it is captured (still theoretical because of price but the cost is dropping, see below), either sequester it and remove it from the carbon cycle or reuse it in a closed loop hydrocarbon fuel infrastructure.
From 2007: "Can baking soda curb global warming?":
I have a fascination with calcium carbonate. But, being flexible, I am willing to consider the bicarbonate of various metals.
Some scientists have proposed compressing carbon dioxide and sticking it in underground caves as a way to cut down on greenhouse gases. Joe David Jones wants to make baking soda out of it.
Jones, the founder and CEO of Skyonic, has come up with an industrial process called SkyMine that captures 90 percent of the carbon dioxide coming out of smoke stacks and mixes it with sodium hydroxide to make sodium bicarbonate, or baking soda. The energy required for the reaction to turn the chemicals into baking soda comes from the waste heat from the factory.
"It is cleaner than food-grade (baking soda)," he said.
The system also removes 97 percent of the heavy metals, as well as most of the sulfur and nitrogen compounds, Jones said.
And a few months earlier:
... Right now I'm looking at calcium carbonate. Literally. Got a hunk of limestone. CaCO3. That's sequestered carbon, right?. Hmmm.
Make a green pitch, wrap it in recycled fiberboard; et voila! Return of the Pet Rock, eco-version! And seashells, same stuff, calcite. There's the hook! Mom, you're going to Miami Beach.
And many, many more. Use the 'search blog' box if interested.

Here's another approach to capture, from IEEE Spectrum:

A material called ZIF-8 swells up when carbon dioxide molecules are trapped inside, new images reveal
A new kind of molecular-scale microscope has been trained for the first time on a promising wonder material for carbon capture and storage. The results, researchers say, suggest a few tweaks to this material could further enhance its ability to scrub greenhouse gases from emissions produced by traditional power plants.

The announcement comes in the wake of a separate study concerning carbon capture published in the journal Nature. The researchers involved in that study found that keeping the average global temperature change to below 1.5 degrees C (the goal of the Paris climate accords) may require more aggressive action than previously anticipated. It will not be enough, they calculated, to stop building new greenhouse-gas-emitting power stations and allow existing plants to age out of existence. Some existing plants will also need to be shuttered or retrofitted with carbon capture and sequestration technology.

The wonder material that could potentially help is a cage-like lattice inside which individual carbon dioxide (CO2) molecules can be trapped. Called a metal-organic framework (MOF), the material (consisting of metal ions attached like K’NEX hubs to rods made of organic molecules) also holds promise as a medium for drug therapies, desalination filters, nuclear waste containers, and photovoltaics.

Researchers are exploring MOFs because the materials can envelop many carbon dioxide molecules at once. The reason has to do with their remarkable sponge-like quality of containing holes and hollows nearly anywhere in the molecule one cares to look. Unfold all the caverns contained within an MOF into a single sheet, and just one gram of the stuff contains enough molecular surface area to occupy two football fields. Which can translate to a lot of holding space for CO2—or many other types of molecules.

However, a CO2 molecule venturing into a MOF is like a mouse entering a Rube Goldberg mousetrap. It’s a complex and delicate process—so much so that the interaction had previously only been the subject of educated guesswork, and never directly observed.

Now, a new bio-imaging technology (itself the subject of a 2017 Nobel Prize) has captured the world’s first images of CO2 molecules caged inside a MOF. The images, the researchers say, provide the first glimpse into the ways carbon dioxide wanders into the cage and how that same trap can be made bigger and more absorbent. Further imaging and study, they say, would enable researchers to engineer, as it were, a better and more effective CO2 “mousetrap.”...MUCH MORE