Carbon dioxide turned into hydrocarbon fuel

New Scientist ^ | July 31, 2002 | Eugenie Samuel

[Paradox]

A note to the Luddites, (maybe, just maybe), technology may have gotten us into this mess, but technology can get us out of it.

[monocle]

Hydrogen chloride and the potential byproduct chlorine are both highly toxic and corrosive and could be factors limiting commercialization. Also, the cost of producing hydrogen chloride must be factored in.

[boris]

Yawn. See: sabatier process. The hitch is probably that making hydrocarbon fuel from CO2 requires more energy than buring the fuel will supply! "Sabatier Process

The CO2 in the Martian Atmosphere will be used to produce methane by the so-called Sabatier process (discovered by the French chemist Paul Sabatier in the nineteenth century). The reaction converts carbon dioxide with hydrogen at elevated temperatures into methane and water (Stephen J. Hoffman, David I. Kaplan,1997):

4H2 + CO2 ---> CH4 + 2H2O

Since no hydrogen is found in the Martian atmosphere, the hydrogen has to be imported from Earth or from the Moon and NEOs. CH4/O2 rocket propellant only consists of 16% hydrogen by mass. Therefore, the reduction in mass that has to be brought from Earth to Mars is still substantial. A quick calculation shows that about 0.222 kg of H2 and 1.222 kg of CO2 are needed to produce 1 kg of water and 0.444 kg of CH4."

[madvlad]

A process involving the production of longer chain
hydrocarbons, including octane, from carbon dioxide and methanol was discovered in the 70s by Mobil I think.
It involved zeolite catalysts which produced long
chain hydrocarbons with each pass of carbon dioxide.

This technology is not new.

I will post the reference next week if anybody is interested.

Mad Vlad

[capt. norm]

"A way to turn carbon dioxide into hydrocarbons has caused a big stir "

Most of us remember from our biology courses that green plants (through photosynthesis) have been doing this for eons.

[sasquatch]

The heat and pressure are low enough, says Yamasaki, to make it feasible to scale up the reaction so it can run on a power station's waste heat

Global warming goes direct or are the first few laws suspended?

[Steely Tom]

There is a class of perpetual motion machines that violates the second law of thermodynamics, instead of the first. Is this an example?

If so, this professor will never live it down.

(steely)

[steve in DC]

Talk to the folks at Dow Chemical in Freeport Texas.

See, they take seawater, and using copious amounts of electricity, turn it into HCl and NaSO4.

Now this nice gentleman thinks he can take CO2 and combine it with the HCl, to create the light petroleum products like butane.

Isn't this a bit like making a perpetual motion machine?

[Doug Loss]

The hitch is probably that making hydrocarbon fuel from CO2 requires more energy than buring the fuel will supply!

Of course it does. If it didn't the 2nd Law of Thermodynamics would have been broken. You do know that the making of gasoline, diesel fuel, etc., also all require more energy than the fuel supplies, don't you?

[boris]

"Of course it does. If it didn't the 2nd Law of Thermodynamics would have been broken. You do know that the making of gasoline, diesel fuel, etc., also all require more energy than the fuel supplies, don't you?"

They do not. The energy in gasoline and other fossil fuels is concentrated sunlight. It was stored over millions of years. Thus we are able to obtain large quantities of energy which have been stored for our use. The total energy pumping the crude out of the ground and refining it cannot exceed what is obtained by burning it. This would be (a) silly, (b) impractical, and (c) useless.

How is the machinery used to make refined fuels to be powered? If making the fuel took more energy than combusting it, one could never make any refined fuel--you'd simply run out of power, unless the entire economy were based on nuclear, hydro, or solar power.

THINK about it before posting such nonsense!

--Boris

[Doug Loss]

You really don't know anything about science, do you?

[OHelix]

I have never heard of sunlight playing any significant role in the formation of fossil fuels... Please provide documentation...

[Paradox]

I have never heard of sunlight playing any significant role in the formation of fossil fuels... Please provide documentation...

Sunlight powers the machinery of the Plants, which grow, then die, then get squishied , heated, and turn into fossil fuels.

[OHelix]

...and BTW, I think you misunderstood the statement you refuted. His statement is correct. He is not referring to the amount of energy it takes to remove the crude from the ground, but the amount of energy that went into producing it in the first place, whether sunlight, as you say, or heat and pressure generated by the earth's gravity.

[OHelix]

I now understand your reference to the sunlight... Thank you...

[Eric in the Ozarks]

You are correct. To say gasoline is stored sunlight is a simplification, but still good science.

[eniapmot]

Do that please. I am not familiar with the one you mention.
I do know of one which mixes CO and H2 in the presence of zeolites.

[Fabozz]

"Isn't this a bit like making a perpetual motion machine?"

It would be, if he were suggesting to then run the power plant off the results of the process and use the plant's electricity to produce the HCl. However, since the system has two energy inputs, the fuel burned by this plant and the fuel burned by the plant powering the HCl factory, it's okay for the end result to contain more energy than one of the two inputs. Essentially, if this process were very efficient, it'd be like running a power plant off HCl rather than hydrocarbons.

Of course, the process won't be even remotely that efficient. Instead, the point is to combine the plant's waste products—heat and CO₂—with HCl to create a product that, one hopes, has more economic value than the original HCl did. Actually, even if the petroleum products have less value than the HCl, this can still make financial sense. It transfers the pollution from this generator to the one that powered the HCl plant; varying regulations may make that worthwhile. And if the HCl plant is run off nuclear power or some other "free" electricity, then the process reduces CO₂ emissions as a whole. Not that there's any objective value to that, but again, regulations may make it worthwhile.

[Eric in the Ozarks]

Its like burning coal to make ethanol. More BTUs of a lower rank fuel are used to make a higher rank fuel that's more convenient to use. And, if you're using a fluidized bed combustor, more low-value high sulfur coal can be put to use.