×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

(OP)
Hello all,

This thread is not intended to re-ignite any debates or arguments about the validity or otherwise of speculations about anthropogenic global warming, please don't turn it into one. I only want to learn the state of advancement of investigation into the subject topic, since, in my view, whether the ability to do something ends up being needed or not, learning how to do something well is never wasted.

MIT posted the following http://pubs.rsc.org/en/content/articlehtml/2013/ee... in regards to this topic, but I'm not sure how to find out what else they or others have done in furtherance of research...

I'd appreciate if anyone could advise me whether a pilot or small-scale prototype project is under development or construction to determine the real-world feasibility of EMAR. If there isn't, I may ask around as to whether perhaps a rehabilitated steamship-based combined cycle power plant of ~ 4 MVA and fuelled with natural gas and/or distillate oil might not prove to be a viable platform for such experimentation.

Thanks.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

The question should be is if the input products have a higher carbon cost to manufacture than the carbon removed.

In one of the proposed process (from somewhere else) to remove carbon in flue gas, the input material must have the existing carbon driven off by heat in order to produce it.

Using CNG or LNG for powering a combined cycle plant is possible, but the storage of the NG is a big concern.

Existing combined cycle, both gas turban/steam, and IC/steam can both use NG as a fuel, but most existing plants use fuel directly from the pipe.

Another type of combined cycle using IC/hot water in buildings has been proposed, but I have not seen much of this. The hot water in this case would not be used to power anything, but would be used for heating.

RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

(I'm not sure what EMAR is...) edit: ah, in the post title, LOL.

Google: saskpower carbon capture

You should find the 'Boundary Dam' project. The project has had issues, but still seems to hold promise.

A few months ago, there was a news item that mentioned that with CO2 in some form injected deep underground, some significant fraction reacted and was converted to a solid. Thus eliminating the risk of it ever bubbling back to the surface. I can't find the link, sorry.

Happy New Year.


RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

I've looked at several ways to source CO2 for tertiary recovery projects in gas fields (same carbon result as sequestration, but with a different economic result). The one that had by far the best economics was to convert a powerplant to oxy-fuel (instead of air-fuel). That gets just CO2 and water in the stack and I could use it directly. Building an air-plant to provide the oxygen (either venting the nitrogen or compressing it for sale depending on local markets did not make a huge difference in the economics since no one is willing to pay much for these small volumes of nitrogen) was a very large expense, but much smaller than trying to get NOx/SOx/CO/BTEX out of the stack gas. Gas separation technologies keep turning out to be really expensive.

I've also looked at pulling the stack gas from an amine reboiler, but the quality is way worse than expected on large-scale units (15% methane in the stack is common, advertised quality is closer to 0.1% methane but I've never seen that on any of the projects I was looking at).

It looks like the big selling point in the linked article was less reboiler energy needed. This is a big deal for overall plant efficiency. Not so much for stack gas quality.

David Simpson, PE
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

(OP)
Hi zdas04, actually no reboiler used at all in EMAR, hence no steam, hence technology reported to be usable in non-steam environments like cement kilns, etc.

Thanks, VE1Bll, for the link to Boundary Dam; one of my co-volunteers aboard the Kee was superintendent of construction for all piping at that site. Thermal re-boiling is clearly used for amine regeneration, something the EMAR referenced in the OP is intended to improve upon.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

After reading the abstract only, I would not be at all surprised if the authors of the MIT paper conflated thermal energy with electrical energy. I have a very tough time believing that on a truly equal energetic basis, it is energetically sensible to use work (electricity) to displace a thermal desorption cycle in an amine absorption system.

RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

(OP)
From what I'm gathering after reading through the whole paper and others like it, the regeneration technique in EMAR is to first replace the CO2 molecules in the loaded amine with a copper molecule, supplying the necessary input energy for this step electrically. Next, using still more electricity, the copper is stripped from the amine so the amine can be re-used; the copper goes back into the regen cycle. I may not be completely precise in this description, but hey, I ain't no Chemistry PhD.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

Exactly- and by so doing, they're using an electrochemical reaction (one driven by electricity, i.e. by something which can be readily and with high efficiency converted to thermodynamic work) to replace a thermally driven cycle- the CO2 is usually driven off the amine by temperature swing, requiring relatively low grade heat. If you compare thermal Joules and electrical Joules as if they're the same, many electrochemical processes can look quite appealing. Not so in reality, where work can be used to pump heat, and conversely, heat can only be partially converted to work.

RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

(OP)
What is your "exactly" referring to - the fact that I ain't no Chemistry PhD? bigsmilenoevil

The one factor not necessarily addressed in what I've seen on EMAR is the possibility, especially here in Ontario, Canada where electricity prices vary on a time-of-use basis, of using amine storage to defer its [electrical] regeneration to off-peak periods. The paper at http://www.geos.ed.ac.uk/ccs/Publications/Chalmers... mentions using amine storage to improve conventional amine regeneration plant flexibility, but I've not been able to find any instances of where this has been attempted - and yes, I've Googled, although maybe I just used the wrong search terms. Of course designing such a scheme would involve lots of investigation as to which amine or amine derivative [?] would hold the most CO2 per unit volume, cost of a tank farm, pumping costs, etc., etc., but it might be interesting to look into.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

It is political, but in many places electric prices don't vary with time of day. This whole fact increases peak demand, which drives less efficient energy production for the peak hours, and thus tends to increase electric prices.

So having off peak electric prices is actually a gift.

Storing materials for off-peak regeneration then becomes an energy storage technology. And for what, to capture energy production carbon.

RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

(OP)
Then again, from a system operator's point of view in a significant-proportion-of-not-readily-maneuverable-nuclear-generation world, it's good to have additional non-nuke generation on-peak that does a one eighty and becomes a load off peak.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

I rather suspect the tankage required would rapidly become prohibitive. It would be a very, very low energy density means of storage.

RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

(OP)
Which is why I was wondering about which CO2 solvent would provide the biggest bang for the buck.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

Then again the more generation assets that can come on-line, the more would need to be spent to obtain the same carbon capture. And what I am saying as assets, is the number of generation units, and not by size (and assuming carbon capture is scalable to all size of assets).

If one believes carbon capture is required, then the cost of FF generation will increase making nuclear generation more affordable, and the same with hydro power.

But as it stands, the hold up on both new nuclear and hydro is the governments magic hand.



RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

Trying to respect the OP's wish to discuss the technology rather than the underlying issues. Cranky's comment prompts me to say that although I am definitely convinced that we need to do something about AGW, I am not at all convinced that CCS is the right way to do it. To me it's merely an opportunity to p*ss through our non-renewable fossil feedstocks even faster, assuming reservoirs sufficient to permanently sequester all that CO2 again for us actually exist (which I'm not convinced of). Frittering around the edges of the problem by optimizing the process by which CCS is attempted (this one or others) is not going to give big gains- ultimately you're fighting the lowest cost (in dollar and energetic terms) method of CO2 disposal that is possible- dumping it untreated to the atmosphere. If I were made benevolent dictator, I wouldn't give full carbon tax credit for CCS schemes.

I'd prefer to see us move to a world where the only fossil-origin materials being burned for energy are those which have already served out a life in another use, i.e. as plastics. Assuming we one day get there, hydrocarbons of non-fossil origin (generated from renewables using renewable energy) would also be fair game, for uses such as aircraft where energy density will always be king. Assuming the toxic emissions are handled during the combustion, I'd be OK with the CO2 from those materials going back to the atmosphere without CCS.

RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

(OP)
Hi moltenmetal, thanks for trying to hew to the original intent; I appreciate it.

Strangely enough, launching this thread prompted me to re-consider our residential home heating set-up, so I'll run just a little with your divertimento...

Presently we heat with oil, but we have a Pacific Energy wood-fueled fireplace insert that burns amazingly cleanly [some of this isn't strictly true, as we have some construction deficiencies to correct since our renovation before we can get back to this state; but I'll ignore that for the purposes of this thread]. We have heated mainly with wood for several consecutive winters, and have been very happy both financially and from a stretch-those-non-renewable-fossil-fuel-resources point of view.

Nevertheless, I think we can do even better...

I'm thinking of adding a ground source heat pump to our mix; since the lion's share of the electricity generation in our province is either nuclear or hydraulic, we would be able to essentially heat our house with next to no fossil fuel consumption at all. There'd be a couple of issues, though, the first being that due to using existing ducts with cross-sectional area originally designed for use with an oil/wood furnace there would be a limit to the heat pump's BTU rating so as to to not provide more capacity than can be transferred into the house due to the delta T limit across the plenum coil. [We had previously looked into using a heat pump as a main heat source, but were told we'd have to enlarge all the house ducting to accommodate the requirement to move enough air to make it feasible; we decided that even if we were willing to gut the house to do this, the end result of so much boxed-in ducting would have looked extremely unsightly, so we rejected the proposal.]

As a result, I'm wondering if anyone knows of different versions of heat pump systems that operate on a different refrigerant, or perhaps using different compression ratios, that would yield a higher compressor discharge temperature, thus enabling us to use the system down to a lower ambient temperature before having to begin supplementing its output with wood heat.

Another issue would be that if we weren't around to stoke the fireplace, the supplementary heat source would be oil, which I'm guessing would mean we'd want to place the plenum coil in the return ducting to the furnace and not in its outlet, since otherwise the air inlet to the plenum coil would have such a high inlet temp that the heat pump compressor discharge pressure would go way up, maybe even high enough to trip it out. I'm thus trying to figure out whether placing the plenum coil on the suction side of the furnace fan would have an adverse effect on its ability to move air...

Thoughts?

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

Raising the condenser temperature to get hotter air will raise the delta T across the heat pump and significantly reduce its thermodynamic efficiency. It has the same effect as lower outside air temp. on a heat pump.

RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

(OP)
...which I should have realized; greater proportion of heat of compression/total heat transferred means a lower coefficient of performance. Duh! So I'd have to stick with one of the well-established cycles, using reputable equipment.

Next I'm wondering if non-reciprocating [read: centrifugal] refrigeration compressors are made in such relatively small capacities, and how efficient they are; I have my suspicions that centrifugal compressors don't scale down well, since the mechanical clearances between parts can't be scaled down along with the sizes of the parts themselves...or are there non-wearing designs of rotary compressor I should be looking at?

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

Decent refrigeration compressors these days are scroll type units, which are positive displacement. I don't know whether or not giant multistage centrifugals are used for giant refrigeration units- not really sure what the required compression ratio is actually.

If you don't have the ducting required to distribute the heat, you can presumably go with a fan coil sized for the ducting you have, plus one or more separate ductless wall mount fan coils. "Mini-split" units like this are commonly used for air conditioning in homes with radiant heating. If you go with groundsource heat pumping, you'd ditch the oil system entirely.

I regret that when I installed ducted air conditioning for the top floor of my radiant-heated house, I didn't design the sysetm for air source heat pump operation. It would have been useful for heating in the spring and fall. However, natural gas is so cheap and our boiler and associated system is so efficient that it wasn't worth the bother at the time. Heating and cooling the whole house with groundsource heat pumping wasn't a financially viable option for us- our addition was expensive enough at the time. Since our preference is for radiant heating (both for comfort and because forced air aggravates my wife's allergies), it would have been a very expensive system.

Ground source heat pumping is of course a great thing from a greenhouse gas emission perspective assuming you have access to a clean grid (Ontario, Canada like me?). However, if the groundsource wells or trenches are not designed properly such that they have sufficient independent heat transfer capacity, their COPs can be poorer than expected. And power here is not cheap, particularly on peak. Even before I started charging an electric vehicle in the evenings, I was still paying more for electricity than for natural gas. That would of course change if we had a substantial carbon tax...



RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

Of the newer ductless type of units, I don't know of any that would work with a ground source. But if they existed,that might be a solution to enlarging the duct work.

So how do you presently move the air for your wood fueled fireplace?

RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

A ductless unit is just a fan coil without ducting, is it not? I haven't personally looked to see if these coils can be used as both condensers and evaporators, but it appears that the Mitsubishi units can do so as they are used as both air conditioners and heat pumps:

http://cozycomfortplus.com/mitsubishi-ductless-spl...

For use with ground source, you'd pair one or more of these ductless fan coils not with the usual compressor unit with air exchanger, but rather with a heat pump compressor unit fitted with a glycol or ethanol pumped groundsource exchanger (i.e. with the ethanol or glycol/water pumped through the tubing in the wells or trenches on one side of the exchanger, and refrigerant condensing or evaporating on the other depending on the mode (A/C or heat pump).

In my situation, because I had no forced air furnace and didn't need one for heating, I used an ADP air handler (coil and fan in a duct box) and installed insulated ducting in the attic. But I cheaped out and went with A/C only, with an ordinary Keeprite compressor/condenser unit rejecting to air.

If you use more energy for heating than for cooling (I suspect that'd be your case), then you'd want the compressor indoors so you get the benefit of any heat rejected by the motor and compressor in winter. Cooling with such a system is nearly free in energy terms- the COPs can be very high indeed, as you don't really even need the compressor. The glycol/water or ethanol coming out of the ground is cold enough to do the cooling directly, although going that route would likely do a poor job of dehumidification. Here in Ontario, proper dehumidification is more important than bulk cooling for summer comfort.

I see no reason off the top of my head that such a system would have difficulty handling split refrigerant to/from a couple different fan coils in a mini-split system configuration, but this isn't my area of expertise for sure.

It would take a clever HVAC guy to design this system for you properly as it's a bit out of the ordinary. You'd need someone who can actually engineer it for you rather than just looking things up in manufacturer's catalogs, but such people can be had if you can find and pay them properly. It wouldn't be cheap though- the ground source system work alone is a big expense. Payback against gas heating is going to be very long indeed- unless there is no gas available in your area.

RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

(OP)
Hi moltenmetal, unfortunately no natural gas lines run in front of our place at the moment; the closest location from which it could be run is ~2 km away, and a bunch of neighbours would have to get together and agree to extended closed contracts before Enbridge would even consider putting in a radial spur down our way.

As to cranky108's question, the fireplace insert has its own jacket circulating fan, and if the living room gets too warm we run the furnace circ fan to distribute the heat around the rest of the house.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

I suspect you'd install one fan coil in your existing ductwork- as big a unit as that ductwork and fan could properly support- and one or more ductless units in any large rooms which get cold (or hot in summer) because your existing ducting is undersized. You could supplement/unload the groundsource heating system any time by burning your woodstove. Sure, you'd take a minor efficiency hit on your ducted fan coil due to increased air temperature while you're burning your woodstove, but that would be more than offset by the heat provided by the stove.

RE: Post-Combustion Carbon Capture - Electrochemically Mediated Amine Regeneration

(OP)
Thanks for the suggestions, all. As to the OP topic, I'll let y'all know what I find out. Stay tuned...

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources