crude oil from algae

[Borgholio]

A high enough concentration of CO2 is definitely hazardous. When looking at the deadly smogs in China for example, would the concentration of CO2 there be high enough to cause a problem?

[energiewende]

CO2 can be dangerous in very high concentrations, of order 100-1000x average atmospheric concentration. Generally though carbon monoxide is the limiting factor because it is dangerous in much lower concentrations and produced by many of the same sources as CO2. It's also much less stable in the atmosphere. Deaths due to CO2 pretty much only happen in confined spaces.

[Grumman]

A high enough concentration of CO2 is definitely hazardous. When looking at the deadly smogs in China for example, would the concentration of CO2 there be high enough to cause a problem?

No, because it's not the CO2 that makes smog dangerous. It's everything else in the smog that might kill you - ozone, carbon monoxide, sulphur dioxide and so on.

[Beowulf]

CO2 can be dangerous in very high concentrations, of order 100-1000x average atmospheric concentration. Generally though carbon monoxide is the limiting factor because it is dangerous in much lower concentrations and produced by many of the same sources as CO2. It's also much less stable in the atmosphere. Deaths due to CO2 pretty much only happen in confined spaces.

Even with confined spaces, it's unlikely, as carbon monoxide is usually the killer. Most likely death from CO2 is due to volcanic activity. There's a lake that holds a massive reservoir of CO2, and burps occasionally, resulting in mass deaths as the CO2 displaces air, and asphyxiates people. The only other situation is if you have a bag over someone's head, or lock them in a room with a CO2 source, like tank of compressed CO2 or dry ice.

[Zeropoint]

You wouldn't claim water is toxic to humans even though it doesn't take much of it to kill a human being.

You wouldn't claim that bullets are toxic to humans even though it doesn't take many of them to kill a human being.

Toxicity isn't just about whether something is dangerous to human health and life, it's also about how it harms people. Inhaling water can kill by depriving the lungs of oxygen to absorb--that isn't toxicity any more than killing by blunt trauma or blood loss. Carbon dioxide can cause unconsciousness and death in concentrations around 10%, even if there's still plenty of oxygen in the air, and it does so by chemical effects at a cellular level.

[energiewende]

Water can actually have toxic effects in humans, aside from being an asphyxiant. So can carbon dioxide. But in common speaking it's still not correct to call water a 'toxic chemical', because the required doses are impractically high to be relevant in all but a handful of weird cases.

[Zeropoint]

Sir, I will fight TO THE DEATH over this seemingly minor issue of terminology, because this! Is! THE INTERNET!

Well, I would, but it's about dinner time.

[aussiemuscle308]

That's pretty neat. I recall experiments with algae where they have huge tubes of the stuff in the desert producing hydrogen gas that can be collected and used for fuel.

There was one pilot plant on tv yesterday, that produces ethanol from algae and it's set up in the desert to take advantage of the sunlight. the algae has been genetically modified to produce ethanol as a by-product.