Freeing Hydrogen From Glucose

tarawa writes: "This story at CNN reports that researchers have developed a new and easy way to extract hydrogen from a glucose solution that could provide a clean, environmentally safe fuel for our cars in the future." Stay calm, though -- ""We are not talking about spooning glucose into your car to make it go. That is 'Back to the Future' stuff."

Comments

PEOPLE!

[Thoth Ptolemy]

Accelerant glucose is made of people!
IT'S MADE OF POOOOEEEEPLLLLEE!!!

Re:Questions for the chemists

[GMontag451]

How much heat do you get from C6H12O6 + 6O => 12H + 6CO2? And what is the molecular mass of C6H12O6?

First of all you wouldn't get 12H, you'd get 6H2. I don't know about the heat, but the molecular mass is pretty easy to figure out. 6C = 6*12. 12H = 12*1. 6O = 6*16. That makes 72+12+96=180. What I want to know is how they are keeping the H2 from combining with the O2 at those temperatures.

Two inaccuracies in the story

[GMontag451]

He says the process does not produce extra carbon dioxide, as this would have been released back into the air anyway through biodegradation of the plants.

This statement, which I suppose is technically true, is absolutely ludacris. It would be like saying that burning down the rainforest wouldn't produce any extra carbon dioxide for the same reason! If this process becomes widespread, even though it won't technically produce any more carbon dioxide than would have been produced, it will produce it a hell of a lot faster and there will be higher concentrations of it in the atmosphere.

At present in the laboratory bench process, hydrogen constitutes about half of the product from a catalyzed glucose solution. But with further refining of the sugar solution the percentage rises.

The percentage cannot rise above 50%. The reaction is C6H12O6 (glucose) + 6O2 -> 6H2 + 6CO2. And that's only 50% by volume. By mass its only 4.3% H2 and 95.7% CO2.

Re:Two inaccuracies in the story

[famebait]

This statement, which I suppose is technically true, is absolutely ludacris

Nope, nor is it ludicrous; it is common sense, as long as the fuel is produced from cultivated plants. And the article did say renewable sources.

It would be like saying that burning down the rainforest wouldn't produce any extra carbon dioxide

No, that would contribute extra CO2 until the areas grew back with an equivalent amount of biomass. After that the balance would be restored (as long as we're talking only about CO2), but it would take a long time and there's no guarantee it would happen at all. Rainforests are not generally considerd a renewable resource in practice. Normal farmland is usually renewed all the time.

it will produce it a hell of a lot faster and there will be higher concentrations of it in the atmosphere.

The speed of the carbon cycle is irrelevant, the important part is how much carbon is bound up in plants and elsewhere and thus kept out of the atmosphere at any given time. I can't see how this fuel scheme would be different from any other cultivation on the same land in that respect.

Another question is whether it is ethical or viable in the long term to use land for growing fuel in stead of food, but that is a very different matter.

Re:More efficient is more CO2

[norton_I]

Except that glucose would be made by photosynthesis, which is a C02 consuming process. So this would not release any "fixed" CO2.

Possibly an answer

[Spamalamadingdong]

What I want to know is how they are keeping the H2 from combining with the O2 at those temperatures.

They don't, because there is no O2; they start with a water solution of glucose. The reaction would appear to go something like this:

C6H12O6 + 6 H2O -> 6 CO2 + 12 H2