Saturday, November 2, 2013

Energy Dept. Seeks Company to Turn Sunshine Into Gasoline

I'm not sure why we would want to take food - that being the carbon dioxide - away from the plants.  But, ok.  Let's go with it.

Researchers have been working on this idea for some time, according to a 2007 press release from the Sandia lab. At that time, one of the researchers speculated that although a prototype of a device to carry out the chemical process was already under development, it was "a good 15 to 20 years away from being on the market."

You can follow the link to the 2007 press release here.


Using concentrated solar energy to reverse combustion, a research team from Sandia National Laboratories is building a prototype device intended to chemically “reenergize” carbon dioxide into carbon monoxide using concentrated solar power. The carbon monoxide could then be used to make hydrogen or serve as a building block to synthesize a liquid combustible fuel, such as methanol or even gasoline, diesel and jet fuel.

...

“Our overall objective with this prototype is to demonstrate the practicality of the CR5 concept and to determine how test results from small-scale testing can be expanded to work in real devices,” Miller says. “The design is conservative compared to what might eventually be developed.”

Diver says the prototype should be completed by early next year. He hand-built the precision device in a shop at Sandia’s National Solar Thermal Test Facility and is now waiting on a few parts to finalize it. Initial tests will break down water into hydrogen and oxygen. That will be followed by tests that similarly break down carbon dioxide to carbon monoxide and oxygen.
The idea is interesting, and looking on the web it looks like others have come up with the idea (follow this link)....but.  And there are two buts.

The first kicker is the conversion of water to hydrogen and oxygen. The oxygen is for the most part, thrown away and the hydrogen is used with a Fischer-Tropsch reactor to convert the hydrogen and carbon monoxide to usable fuel.

At the present, there is no cheap or efficient way to convert the water to oxygen and hydrogen.  The near term solution - which is not a GREAT solution but relies on conventional technology - is to perform what is called a Shift Reaction.

You take some of your CO (carbon monoxide) combine it with water and  create hydrogen...and CO2 - carbon dioxide.  In essence, you put all that effort in converting the CO2 to CO, only to have to take half of your CO to convert it BACK to CO2 in order to get the amount of hydrogen you need to make the fuel.  That's the second but.

Just like for conventional refineries, the technology bumps into the scarcity of hydrogen.



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