CO2 Removal from Plant Stacks
CO2 Removal from Plant Stacks
(OP)
I was wondering,.....with the current emphasis on "greenhouse gases" and global warming, how practical is it to remove CO2 from the effluent of a Combustion turbine power plant ? Are there any demo or pilot plants in operation ?
How is the CO2 collected and where does it go ?
How about a gas-fired combined cycle installation ? (The kind, of course, that is now being constructed all over the USA) If the plant emitts less CO2, don't we end up with a big pile of "something" that requires disposal ?
I realize that nuclear plants really are bad in the eyes of many, and that nobody want's them on the planet.... but, after we burn through all of our natural gas and had a few more war's in the mid-east over control of oil...... what is our only real option ??
Who knows something about the practicality of CO2 removal ?
Any websites ?
Thank You !!!
MJC
How is the CO2 collected and where does it go ?
How about a gas-fired combined cycle installation ? (The kind, of course, that is now being constructed all over the USA) If the plant emitts less CO2, don't we end up with a big pile of "something" that requires disposal ?
I realize that nuclear plants really are bad in the eyes of many, and that nobody want's them on the planet.... but, after we burn through all of our natural gas and had a few more war's in the mid-east over control of oil...... what is our only real option ??
Who knows something about the practicality of CO2 removal ?
Any websites ?
Thank You !!!
MJC





RE: CO2 Removal from Plant Stacks
Chemical absorbtion is the most suitable method of removing CO2 from exhaust gases whre the CO2 concentration is typically between 5% and 15% by vol. There is a commercially available process which uses aqueous solution of amines as solvents. Using this process, a recovery factor of 90% of CO2 in feed flue gas is possible. The separation process of carbon dioxide by chemical
absorption consists of two steps:
1. the absorption of CO2 by chemical solvents at a low
temperature (40-65°C)
2. the recovery of CO2 from chemical solvents by using low
grade heat (a temperature in the range of 100-150°C),
usually extracted from power plants.
I think MHI is one vendor of these systems.
RE: CO2 Removal from Plant Stacks
Note that, while this process does strip CO2 out of the exhaust gas, the ultimate "resting place" of this CO2 is probably still in the atmosphere. The Co2 is sold into the market and used for things like carbonation of beverages, electronics manufacturing, dry ice, etc.
RE: CO2 Removal from Plant Stacks
Thank you for your comments.... you have confirmed what I have suspected - that the ultimate repository for CO2 (and all other greenhouse gasses) is the atmosphere....... if there is a brief stop in a carbonated beverage ( or beer, for that matter)what untimate difference does this make to "global warming" ?
I suspect that we will find that any permanent absorbtion and storage of CO2 will be far more expensive than any of our lawyer/lawmakers or environmentalists will lead us to believe.
Does anyone know of any studies or methods that are being evaluated currently ?
Are there any chemists out there in cyberspace that can shed light on any options available ?
MJC
RE: CO2 Removal from Plant Stacks
There as been some "scince fiction" scheem dealing with sea bootom storage (many areas of the sea have sufficient depth to ensure that the CO2 stays liquid and liquid CO2 is heavier than water) or re-injection into oil/gas reservoirs
Best Regrads
Morten Andersen
RE: CO2 Removal from Plant Stacks
Ultimately, it appears that a hydrogen based economy powered by nuclear energy will replace our oil based economies, and bio-energy (solar), like vegetable oil fuel will also help .. injecting CO2 to greenhouses sounds interesting, although perhaps expensive. Ultimately, it appears that the source of all our energy is nuclear energy...
One thing to note in a hydrogen economy, hydrogen is so light that it escapes from the atmosphere into space ... so lets not waste that. Interesting future challenges... gotta love chemical engineering...
RE: CO2 Removal from Plant Stacks
I´m making the reserch here in Venezuela but at until now we dont have much information about it, pleas if anyone can give us some information we will realy apriciate that.
RE: CO2 Removal from Plant Stacks
You will find basic knowledge of CO2 capture.
Furthermore you will find out that CO2 capture
decreases plant efficiency by approx. 10 pct
points, and will result in much higher energy
prices.
RE: CO2 Removal from Plant Stacks
RE: CO2 Removal from Plant Stacks
Regards,
Truth: Even the hardest of the problems will have atleast one simple solution. Mine may not be one.
RE: CO2 Removal from Plant Stacks
One question you asked in passing hasn't been addressed: why do gas-fired combined cycle plants emit less carbon dioxide?
Two answers:
1. Natural gas contains a much higher percentage of hydrogen and lower percentage of carbon than the other usual fossil fuels, coal and oil. Therefor, for a given energy output, more water vapor (H2O) and less carbon dioxide (CO2) is produced. (And so do other gas fired steam electric generating plants, but then I have heard it stated that water vapor is also a greenhouse gas - presumably, however, it is more beneficial to the environment than CO2.)
2. Combined cycle gas-turbine (versus simple cycle gas turbine) plants are much more efficient than conventional steam electric generating plants. FYI: a simple cycle gas turbine is simply a jet engine using a turbine to turn a generator; a combined cycle electric generating system utilizes the power of the jet to turn a turbine wheel attached to a generator, then runs the hot gases through a steam boiler and uses the steam power to generate additional electricity.
I am in favor of combined cycle power generation (fuels other than natural gas are also used, though they are generally less friendly to the environment than the gas fired units), even though they are partially responsible for ending my 30 year career servicing the power industry.
RE: CO2 Removal from Plant Stacks
RE: CO2 Removal from Plant Stacks
I would be interested to know of any products for emissions removal from the exhaust of heavy fuel oil generating plant. - or if a similar device as discussed previously can be adapted for use with these.
I would appreciate any practical knowledge or advice, and also any other information to do with emissions and limiting greenhouse gases.
Thanks
RE: CO2 Removal from Plant Stacks
Just look at it this way. The CO2 is present because the energy in a hydrocarbon fuel was released when its carbon and some oxygen (among other contributors to the combustion process) combined. To tie up the carbon in any fashion other than natural processes like growing trees, thank you Quark, and grass, etc., the conversion of the CO2 to any form other than beer foam is going to require more energy to reverse the process than was released in the creation of the CO2.
Frankly, I am a fan of carbon storage. First grow the tree, like Quark says, but if it is allowed to grow old and die and fall over in the forest, then, it too, releases the carbon it captured as CO2 as it rots, using again the atmosphere as the final resting place of CO2.
However, when a tree is cut down and made into a piece of lumber, and put into a use that ties it up for a long time, such as a wall in a structure, or a timber in a mine, or into a piece of paper that will sit in a file cabinet for 100 years, or be put into a landfill dump, then the carbon that the tree removes from the atmosphere is stored. Anything that is burned just releases the carbon again into the atmosphere (here we are again).
Other materials store carbon in minor amounts, but wood and paper are the best, so the tree huggers are actually working against us. Hug a logger. Build a wood house.
rmw
RE: CO2 Removal from Plant Stacks
All the ideas above have been interesting. However, I would like to point out that you have ignored the largest carbon respository on our planet, the oceans. Take a look at ocean water chemistry (not deep sequestration as was mentioned above) and you'll see that the worlds oceans scavenge CO2 from the atmosphere and convert it to carbonates which eventually are incorporated into coral reefs and limestone. They will continue to do so as long as we preserve them. One of the reasons we don't really know the global warming effects of CO2 better than we do is the lack of knowledge concerning CO2 absorption by the worlds oceans. We know it occurs, just haven't defined the mechanisms well enough to use them as an accurate part of our predictive efforts.
rmw, you are right, trees eventually grow old, fall down and decay. But, if we've planted a new tree to replace it, then we'll balance that out! However, the trees we cut right now to make all that lumber and paper are the ones that were removing CO2 from the atmosphere yesterday. Real problem is that we aren't putting them back! Worldwide, deforestation is a huge problem and this is only one of the ramifications. So please be selective about the loggers you hug!
Quark, have you tried to figure out how much beer foam we might need to generate? Seems to me that we could sit around under a tree at the seaside drinking all of that beer and consider ourselves quite the world savers!
RE: CO2 Removal from Plant Stacks
I lament the slash and burn land clearing techniques of some countries with wonderful rain forests.
Sequester some CO2, build a log house, and file away some papers.
rmw
RE: CO2 Removal from Plant Stacks
"I only hug the LAWYERS ..."
I suspect this is something of a Freudian slip - you know, where you say one thing but really mean your mother.
RE: CO2 Removal from Plant Stacks
Good catch.
It was late, way past my bedtime. What a slip!!! Somebody sabatoged my post, I'm sure. I couldn't have said that, could I???
I am still laughing!!
I gotta e mail this to my friends. They need a laugh.
Now, go out and hug a logger. I won't want to suggest what to do to a lawyer in a forum as fine as this one.
rmw
RE: CO2 Removal from Plant Stacks
Is this possible?
(in the process of contacting my University PhD professor, specializing in Nuclear & Plasmas).
RE: CO2 Removal from Plant Stacks
RE: CO2 Removal from Plant Stacks
Currently, the coal plants are based loaded and the gas fired combined cycle plants in the US have a capacity factor of about 35% ( ie, they are shut down at night).
In order to reduce the US emission of CO2, one would need to reverse this schedule, ie, base load the gas fired combined cycle plants and load cycle the coal plants. Such a scenario would require:
a) LNG terminals to incrase the available gas supplies
b)modify the coal boilers for variable pressure cycling operation
c)a carbon tax to provide a finacial incentive to switch the load schedules
For this reason, there is proposed the Carper bill in the US congress to tack on a $20/ton CO2 tax to coal fired plants.
RE: CO2 Removal from Plant Stacks
rmw
RE: CO2 Removal from Plant Stacks
Your idea and Carpers seems to be a particularly bad one now that there is a natural gas shortage.
In addition, it should be noted that base loaded plants are built differently than cycling plants. It is not as simple as turning a switch to stop and start a plant. The powerplants must be designed mechanically and thermally to be able to accept the thermally induced stresses that occur when the heat goes on and off. For that reason, there will be major consequences from the recent construction of all the turbines units. Gas turbines are not generally designed for cycling operation.
Coal gasification may be the better way to go.
rmw,
I don't know why you make the statement about people's driving and taxes. There definitely is a point when the price of fuel will cause a change in driving habits.
RE: CO2 Removal from Plant Stacks
(I know, I know, there are always the exception out there to my generality.)
When taxes as a percentage of the (formerly lower) total fuel cost were higher, it didn't slow us down much then. So, unless taxes are raised substantially, I don't see that making much difference.
I don't think our politicians have the will, nor would I have the will to permit them to raise taxes along the lines of the european model where gov'ts keep the price of fuel artificially high via the use of taxes.
I don't think americans in general want to drive european type 'wind up' cars over the vast expanses of our landscape. On the other hand, I would drive a hybrid for a commuter car in a heartbeat if I were in the market for a new auto.
Now, not to confuse that with your point, which I actually agree with. Higher prices, wherever they come from, raw material and/or operating costs or taxes, are going to drive markets to different solutions. Further, I predict that driving habits and vehicle types will soon change, as they did back in the '70's. Bye Bye SUV's as the commuter car of choice.
And, I don't mind being part of the change based on my personal choices. I just don't want politicians doing it by taking my hard earned dollars and doing with them the type of things that politicians are famous for doing with tax dollars.
rmw
RE: CO2 Removal from Plant Stacks
The CO2 that is left is pumped into oil wells. Apparently it gives a better oil recovery rate than traditional methods.
athomas236
RE: CO2 Removal from Plant Stacks
But, one has to have an available oil field fairly near to the source of CO2 in order for their to be a market for that by product.
Ammonia plants produce CO2 as a by product (they want the H from CH4) and I heard of one plant, Enid OK, as I remember, that sold its CO2 for that purpose. I knew of others located closer to oil fields that couldn't give the stuff away, and just vented it to the greenhouse.
Not many operating ammonia plants in the USA today due to the price of CH4.
rmw
RE: CO2 Removal from Plant Stacks
True, a cycling plant is built differently than a base loaded plant. True, few US coal fired units are designed for cycling; in fact to date, ASME section I does not even recognize cyclic fatigue damage.
Most US gas fired combined cycle power plants are operated in a 2-shift mode of operation ( ie, shut down at night) , due to the high cost of fuel, yet their HRSG's were not designed to handle this mode of operation well,and these units are experiencing accelerated fatigue damage to their components. This is partly due to the fact that design code used ( ASME I ) does not recognize fatigue damage, partly due to the conventional use of a horizontal gas flow/ vertical tube orientation yields a thermo-mechanical design that does not tolerate the high , transient ,tube-to tube temperature unabalances which occur during frequent startups, but mostly due to fact that the extremely competitive market conditions cause the designers to cut too many corners . So the comment about cycling damage is actually universally applicable to nearly all US power plants, not just coal fired units.
Two shift cycling ( ie shut down at night) is far more dmaging than load cycling ( drop load to 30% MCR at night), and for that reason one would only contemplate cycling a base load desinged coal fired plant to 30% load at night . This is due not only to limt fatigue damage to pressure parts, but also becuase many units have been retrofit with SCR's and scrubbers in a manner that indicates they cannot operate this equipment at lower loads.
Load cycling can be successfully applied at many coal fired units, with (minor) modfications in many cases . First, to limit the heat rate penalty associated with constant throttle pressure operation, the boiler would need to be modified to variable pressure operation. The minimum cost change to effect this would be to use the older B+W patent of "dual pressure " operation, that is , a pressure reducing valve PRV is placed at the primary superheater outlet; the drum , waterwall, and economizer are operated at constant pressure, while the final superheater operates at sliding pressure. Other physical changes would likely include adding relief valves upstream of the PRV and upgrades to control logic, spray attemporator, and pressure part fatigue monitoring as per TRD 301 annex 1. If this method is not used, then the more costly change of upgrading the superheater tube materials and supports would be required.
For those that need to frame everything in dollars, the Carper solution ( ie adding a $20/Ton CO2 tax) could only be rationalized if the long term "externality" associated with emitting CO2 was proven to be at least as large as $20/ Ton . But in any event, a political solution is a political solution, which means, logic and rational thinking is purely optional.
RE: CO2 Removal from Plant Stacks
RE: CO2 Removal from Plant Stacks
The company I work for, just finished a CO2 saving project in Holland.
The company usses an old, unused pipeline that goes right through a large greenhouse area in the country. They buy the CO2 from a refinery, (the CO2 is pure enough to use) then we compress it to about 50bar and distribute it through the pipeline. The greenhouses are connected to the large pipeline. At the greenhouse the CO2 is reduced in pressure.
The greenhouse farmers were first using tanks with liquied CO2 and an evaporator to supply extra CO2 to their greenhouse, others are heating extra during the summer time, not that they need the heat, but they use the CO2 that is produced in the burningproces of natural gas.
In this case, they save on natural gas.
Totaly a lot of CO2 is saved every year.
I also know of other projects where they pump CO2 into old gaswells or old saltwells and store the CO2 in there.
Cryotechnic.
"Math is the ruler of your potential succes...."
RE: CO2 Removal from Plant Stacks
Here is what the feds plan to do....
http:/
-MJC