I came across an interesting article at physorg.com today. The actual Scientific Paper can be found at the Journal of Physical Chemistry Letters.

The article describes a new reactor that uses solar heat + photovoltaics to drive a reaction in a molten salt reactor that splits carbon dioxide (C02) into raw carbon (C), or carbon monoxide (CO) depending on the conditions (temp etc.). They claim solar efficiencies of 34-50%.

The paper's lead author is Stuart Licht, a respected electrochemist and Professor of Chemistry at George Washington University along with his students/postdocs and a collaborator from Howard University.

The method uses solar light both as a heat source and as a source of electricity (via photovoltaics) to drive electrochemical reactions in a molten lithium carbonate flow reactor.

from the Physorg.com article:

"The significance of the study is twofold," Stuart Licht, a chemistry professor at George Washington University, told PhysOrg.com. "Carbon dioxide, a non-reactive and normally difficult-to-remove compound, can be easily captured with solar energy using our new low-energy, lithium carbonate electrolysis STEP process, and with scale-up, sufficient resources exist for STEP to decrease carbon dioxide levels in the atmosphere to pre-industrial levels within 10 years."

Well I probably would not be that enthusiastic, but I really think this approach may have potential to be adopted for large scale applications as it is relatively simple in principle. As usual, the challenge would lie in the scale up engineering.

What got me excited at first was the ability to convert CO2 to Carbon which could be safely buried or used as a biochar like material to enhance soil quality and thereby sequester carbon.

Now the first caveat I thought of was....'man this is going to be expensive'

You would need one of those solar thermal collectors that use a lot of mirrors to focus sunlight onto a reactor that also has some solar photovoltaics to provide electricity to power the reaction. The heat component facilitates the reaction (~850 C for carbon production & ~950 C for CO production).

CO is a feedstock for fuel production when reacted with other compounds like hydrogen gas (H2) which can also be produced from water with solar generated electricity.

Thus this is also a process that can create fuel from thin air

and that my friends is how you can pay for this.

Damn, I'm getting even more excited.

update: having now read the full original article from the journal. I am even more enthusiastic.

In theory both sodium and potassium can be used instead of lithium (with lower efficiencies).

I'll add that the efficiencies are remarkably high....better than photovoltaics.

The electrodes do not need to be expensive metals (carbon, nickel and nickel alloys work).

at temperatures of 750 C you get about 20:1 C:CO at 950 C you get 100% CO with their experimental system.

in all, my assessment is that this needs to put to pilot scale testing asap!

I'd give it 10 years before they have investigated it enough to know if it can be of use for fuel production and/or climate restoration.