Why can we not cleanly burn things?

[Leros]

Why can we not cleanly burn things (coal, trash, etc)? Is filtering the resulting smoke and C02 really that difficult?

 

[IronWing]

The energy costs of capturing pollutants can reach the point of self defeat where the marginal energy required to capture the next unit of pollutant generates more pollution than is captured. Plus greed.

 

[zerocool84]

Why can we not cleanly burn things (coal, trash, etc)? Is filtering the resulting smoke and C02 really that difficult?

I'm guessing you have no idea how expensive a car catalytic converter is. Imagine that x1000000000000000 and you get a general idea.

 

[Hacp]

Why can we not cleanly burn things (coal, trash, etc)? Is filtering the resulting smoke and C02 really that difficult?

So CO2 is unclean now? Since when?

 

[PowerEngineer]

It's all about your definition of 'cleanly'.

Complete oxidation of the carbon in any fuel will produce CO2. In that sense at least, CO2 can't really be considered as an unexpected, avoidable result of 'burning things'.

That's what makes the CO2 problem much more difficult to deal with. One of the primary reasons that natural gas is becoming so much more popular than coal for fueling new power plants is that it has half the carbon (per MMBTU) and therefore a better bet should we start taxing carbon emissions.

IMHO, the proposals to recapture and somehow sequester the carbon after you've gasified it makes little sense over longer time frames. A gas is bound to escape confinement sooner or later. Better to leave it locked up and buried as solid/liquid 'fossil fuel' if we really want to keep it out of the ecosystem.

 

[lxskllr]

Incinerators work in the high 90s of percentages for cleanliness. They burn very cleanly. The issue is with the sheer tonnage of material burned. Even 1% of a shitload is still a shitload in the end.

 

[edro]

Doesn't high pressure and high temperature burning reduce many compounds down to lower level elements, making less byproducts?
I'm no chemist.

 

[Leros]

I was thinking along the lines of burning trash for energy. Killing two birds with one stone.

Obviously it would only work if it was clean.

 

[Nik]

I'm guessing you have no idea how expensive a car catalytic converter is. Imagine that x1000000000000000 and you get a general idea.

The only reason a cat costs so much is because it's got platinum in it...

 

[Leros]

I'm guessing you have no idea how expensive a car catalytic converter is. Imagine that x1000000000000000 and you get a general idea.

Well a car has certain properties of needing to be lightweight, mobile, and not require any maintenance.

If you could have something larger and immobile, maybe there is an easier, cheaper way to do it.

 

[silverpig]

Why can we not cleanly burn things (coal, trash, etc)? Is filtering the resulting smoke and C02 really that difficult?

Because there's no money in it. The same answer to all of those types of questions

Oh, and it's CO2, not C02.

 

[Leros]

Because there's no money in it. The same answer to all of those types of questions

Oh, and it's CO2, not C02.

I make that mistake by saying "oh" instead of "zero"

"Three" "Oh" "Two" = 302

"See" "Oh" "Two" = C02.

 

[IronWing]

Well a car has certain properties of needing to be lightweight, mobile, and not require any maintenance.

If you could have something larger and immobile, maybe there is an easier, cheaper way to do it.

We do get rid of some types of toxic organics by feeding them into cement kilns. The kilns run hot enough to destroy the nasties.

 

[Freshgeardude]

didnt top gear work on this issue?

They attached a box with these rocks (they apparently use them in caves to keep down co2) to the exaust of a car. they got 0% co2 emissions, but they said that box costed like 90 pounds and would only take you like 5 miles.

EDIT:

http://www.youtube.com/watch?v=qwdsVg99DdE

thats what I was talking about.

6 miles on a highway is 75 pounds lol. and they said like limestone oxide crystals

 

[Gibsons]

Doesn't high pressure and high temperature burning reduce many compounds down to lower level elements, making less byproducts?
I'm no chemist.

The best you can hope for is just CO2 and/or H2O as emissions. That's as clean as it gets. But if you're burning garbage or coal, you'll have sulfur and some metals and whatnot as well, no matter how hot you burn it. Filtering that out is doable, I guess, but not cheap.

 

[Leros]

Can we capture the CO2 and feed it into algae tanks or something like that?

Wikipedia also has an article on ways to store/absorb CO2. http://en.wikipedia.org/wiki/Carbon_sink

 

[dullard]

The best you can hope for is just CO2 and/or H2O as emissions. That's as clean as it gets. But if you're burning garbage or coal, you'll have sulfur and some metals and whatnot as well, no matter how hot you burn it. Filtering that out is doable, I guess, but not cheap.

Bingo. Filtering up to a point is doable, but you can't realistically get every molecule. Garbage and coal have lots and lots of different atoms in it. You can't change those atoms outside of a nuclear reaction. Thus, you will have polutants. Some are easier to get than others, but you can never get them all.

 

[Cheesemoo]

Plasmagasiffication FTW!

They use it in Japan in very small scale industrial factories to dispose of wate. They built the worlds first large scale facility in Port Saint Lucie, Florida. They said they will be able to gassify the all the garbage in the current landfill within 20 years.

Plasmagasiffication FTW!

 

[Sho'Nuff]

Why can we not cleanly burn things (coal, trash, etc)? Is filtering the resulting smoke and C02 really that difficult?

I work for an engineering firm that is presently developing a solution for removing CO2 and other pollutants from coal flue gas. So I can attest that is extremely difficult to remove CO2 on that scale in an cost-effective way.

Methods for scrubbing CO2 from gas streams have been known for a long time. Indeed, scrubbing of CO2 in the gas phase using aqua ammonia has been around since the 1930's or 40's. In that process, most of the CO2 is removed from the gas phase by contacting the gas with chilled aqueous ammonia. The ammonia absorbs CO2 from the gas, producing a CO2 "rich" liquid. The rich liquid is then pumped to a regenerator tower, where it is heated to evolve the absorbed CO2 (for sequestration) and regenerate the ammonia for reuse in absorption.

From a functional standpoint, the ammonia base thermal swing absorption process works well. However, it is incredibly inefficient. How inefficient, you ask? Well, between the cooling and regenerating load, the need for makeup solvent, and the fact that ammonia has a tendency to vaporize, about 30-50% of the net energy of the plant may be required to run such a system. That equates to at least a 50% bump up in energy cost, simply to remove CO2.

Several companies (including my own) and at least one University are researching new ways of absorbing CO2 in the gas phase, with the emphasis being on improving efficiency. New solvents, new regenerators, and energy recovery (well, reusing) solutions are being developed as I type this post. While there has been signifciant improvement relative to ammonia (or even more recently developed solvents such a MEA or MDEA), the concensus in the market is that we might not "quite be there yet."

Also, to put things in perspective, a typical 250 MW coal fire power plant emits 1.1-1.4 million tons of CO2 per year. And that is just one (of thousands) of plants! Now, while I am not a global warming fear monger, I do think it is plain stupid of us to think that we can emit that much of a substance into the atmosphere, and not expect any consequences.

 

[Sho'Nuff]

Can we capture the CO2 and feed it into algae tanks or something like that?

Wikipedia also has an article on ways to store/absorb CO2. http://en.wikipedia.org/wiki/Carbon_sink

Yes, Algae is an option. BUt current algae technology is no more efficient than other options, and it has its own set of issues.

 

[Sho'Nuff]

didnt top gear work on this issue?

They attached a box with these rocks (they apparently use them in caves to keep down co2) to the exaust of a car. they got 0% co2 emissions, but they said that box costed like 90 pounds and would only take you like 5 miles.

EDIT:

http://www.youtube.com/watch?v=qwdsVg99DdE

thats what I was talking about.

6 miles on a highway is 75 pounds lol. and they said like limestone oxide crystals

If they used limestone all they are really doing is converting calcium carbonate to calcium bicarbonate. Because the carbonate is limited to the sample size, you can only get so much conversion.

 

[Sho'Nuff]

Because there's no money in it. The same answer to all of those types of questions

Oh, and it's CO2, not C02.

There is at least some money in certain forms of CO2 sequestration. Sequestered CO2 is useful, for example, in enhancing oil recovery (obtain more oil from old wells). And in some technologies, a portion of the CO2 can be converted into a saleable fertilizer product. Its not enough to be profitable (yet), but a market could develop.

 

[Zenmervolt]

I was thinking along the lines of burning trash for energy. Killing two birds with one stone.

Obviously it would only work if it was clean.

Lots of landfills capture the methane released during natural decomposition and use that for power generation.

ZV

 

[IGBT]

doesn't matter how clean or efficient you get. The eco-KOOKS will always nit pick and find something they can use to incite alarmist dogma. Watch what happens when they catch on to the the EMF fields generated by EV cars and hybrids.

 

[calvinbiss]

I work for an engineering firm that is presently developing a solution for removing CO2 and other pollutants from coal flue gas. So I can attest that is extremely difficult to remove CO2 on that scale in an cost-effective way.

Methods for scrubbing CO2 from gas streams have been known for a long time. Indeed, scrubbing of CO2 in the gas phase using aqua ammonia has been around since the 1930's or 40's. In that process, most of the CO2 is removed from the gas phase by contacting the gas with chilled aqueous ammonia. The ammonia absorbs CO2 from the gas, producing a CO2 "rich" liquid. The rich liquid is then pumped to a regenerator tower, where it is heated to evolve the absorbed CO2 (for sequestration) and regenerate the ammonia for reuse in absorption.

From a functional standpoint, the ammonia base thermal swing absorption process works well. However, it is incredibly inefficient. How inefficient, you ask? Well, between the cooling and regenerating load, the need for makeup solvent, and the fact that ammonia has a tendency to vaporize, about 30-50% of the net energy of the plant may be required to run such a system. That equates to at least a 50% bump up in energy cost, simply to remove CO2.

Several companies (including my own) and at least one University are researching new ways of absorbing CO2 in the gas phase, with the emphasis being on improving efficiency. New solvents, new regenerators, and energy recovery (well, reusing) solutions are being developed as I type this post. While there has been signifciant improvement relative to ammonia (or even more recently developed solvents such a MEA or MDEA), the concensus in the market is that we might not "quite be there yet."

Also, to put things in perspective, a typical 250 MW coal fire power plant emits 1.1-1.4 million tons of CO2 per year. And that is just one (of thousands) of plants! Now, while I am not a global warming fear monger, I do think it is plain stupid of us to think that we can emit that much of a substance into the atmosphere, and not expect any consequences.

Where you at this year's MEGA?

Currently costs of removing CO2 from a coal-fired plant is about $1300/kW-hr which is ridiculous. Plus, the largest scale test facilities out there are about 5 MW and the CO2 scrubber is HUGE! I can't imagine what the size of the scrubber would have to be for my 800 MW plant!!