Comments

1. #1 _Arthur

   2008/01/21

   Why try sequester gazeous or frozen Carbon Dioxide ?

   Why not turn it into pure carbon in solid form, and store it in, say, an empty coal mine ?

2. #2 Benjamin Franz

   2008/01/21

   Why not turn it into pure carbon in solid form, and store it in, say, an empty coal mine ?

   Because it would take more energy to ‘uncombust’ CO2 back to solid carbon than you get from having burned the solid carbon in the first place to generate power.

   Otherwise you would have a perpetual motion machine.

   ;)

3. #3 Hank Roberts

   2008/01/21

   > Why not turn it into pure carbon….?

   Well, then turn it into a different form of pure carbon, like diamonds, and sell them for more than the coal cost before burning it. Our financial system does that sort of thing all the time. Buy a cheap house, get it inspected and valued at three times what you paid for it, get a mortgage on the assessed value, take the 2x overage of cash, buy two more cheap houses …. simple.

   There may be some energy cost for each transaction, but you make up your profit by increasing the total volume and charging fees for each step in advance.

   I’m sure there’s a physical equivalent of this.

   Otherwise our financial system would eventually collapse.

   Oh, wait …..

4. #4 David B. Benson

   2008/01/21

   There is a way to turn CO2 back into ‘pure’ carbon. Begin by growing plants. Take the biomass and, via hydrothermal carbonization, exothermically produce biocoal. There is a demonstration plant producing 75,000 tonnes of biocoal per year, from forestry wastes, in The Netherlands.

5. #5 Adam

   2008/01/22

   “new plants will need to have a big empty space in case they want to fit CCS at some point in the future.”

   I bet this a UK pushed initiative. Next time you travel on the ECML have a look at the power stations (they start just N or Newark). They already have large empty spaces in them, and those that don’t are surrounded by mainly large, empty spaces.

6. #6 bigTom

   2008/01/22

   Interestingly Abu Dubai claims to be building a future carbonfree future. The key is to extract hydrogen from methane and capture and sequester the carbon in the form of CO2. They claim to $15B committed to the overall project!

   http://news.bbc.co.uk/2/hi/science/nature/7200052.stm

   Having to formally leave space for possible future sequestration equipment, I would think would give energy investors some pause. The excuse that it can’t be done will no longer be available, and the potential for an expensive retrofit looms.

7. #7 Dave Briggs

   2008/01/22

   Why try sequester gazeous or frozen Carbon Dioxide ?

   Why not turn it into pure carbon in solid form, and store it in, say, an empty coal mine ?

   Posted by: _Arthur | January 21, 2008 5:41 PM

   I’ve wondered the same thing for years. I think it comes down to expense. I heard on the sequestration that they are talking like 10 years before they think they will have it under control from the power plants.
   Dave Briggs :~)

   [Errm, for the obvious reason: you've just burn the carbon to generate energy. If you unburn it back into carbon it takes all the energy back (plus a bit more) -W]

8. #8 Brian Schmidt

   2008/01/22

   While it’s more plausible to just be leaving space for CCS, it’s far from a huge step forward.

   It’s pretty close to what the Democratic candidates for president are arguing for right now – by itself, not overly impressive.

9. #9 mz

   2008/01/22

   William, do you know anything about the Actual Science and technology of CO2 sequestration? It’s hard to find anything reasonable on the internet…

   For example the expected temperatures and pressures, the availability of large enough underground cavities, leak rates…

   It’s mind boggling how industry just says “ok, we just do it”. How? I see huge show stoppers! It’s happened over here just this week. It’s totally crazy. They’re going to ship it some hundreds of kilometers away, yes, with ships!

10. #10 bigTom

    2008/01/22

    The little bit of stuff I’ve seen:

    IIRC:
    The idea is to get a more or less pure stream of CO2, and compress it into liquid form. Then it can be pumped send via pipeline to a disposal site. I don’t have any reason to beleive geologica disposal won’t work, the biggest problem is the economics of getting separating the CO2 from the other flue gases -mainly N2 and H2O. For InGroundCoalGassification, supposedly the flue gases are mostly CO2, so compression only is allegedly feasable -problem is IGCC always seems to have serious cost overruns. Otherwise chemical absorption with either an amine (or perhaps an ammonia) process removes the CO2. It then must be freed from the chemical absorber, and compressed -supposedly this costs 25-30% of plant output. And of course the recyling of the absorber chemistry must have pretty low losses, otherwise the economics would go to heck.

    Maybe someone knows where a decent review article can be found?

11. #11 John L. McCormick

    2008/01/23

    bigTom, the 25-30% of plant output required to absorb and compress the CO2 is just the opening bid. Add the 9% plant output required to operate the entire plant and its SOx, NOx and ROx capture equipment. Then, throw in a bit more power to pipe the CO2 to its eternal grave.

    So, we are banking on a CO2 disposal technology that requires 1.4 units of power output for each one unit of power demand.

    What will they think of next?

    John L. McCormick

12. #12 bigTom

    2008/01/23

    John:
    Perhaps thats why they have been balking about doing more than tinyscale demonstration projects. And then usually when there is a market (enhanced oil recovery) for the CO2. The proponents of the amonia based method said it would be less expensive -but gave no numbers.

13. #13 John L. McCormick

    2008/01/23

    bigTom,

    Realists agree CCS is a pipe dream. And, there is absolutely no Plan “B”.

    John L. McCormick

14. #14 bigTom

    2008/01/23

    You may be right. The latest word from the Dubai conference -they plan to sequester 20MT/year in 2020. Uhh, (OK its world versus a small nation), but to avoid serious climate change we gotta sequester something like 20GT/year!

15. #15 John L. McCormick

    2008/01/24

    bigTom,

    Another pipe dream (mine)

    Using exit heat from a high temp reactor (pebble bed)to thermochemically split water provides the oxygen for oxycombustion in an ultrasuper critical coal furnace. The predominently CO2 exhaust gas is reacted with the hydrogen in a reverse-water gas shift:

    CO2 +H2 = CO + H20

    The CO is fed into a Fischer-Tropsch unit to produce diesel and other petroleum products such as JP8.

    Jules Verne would have thought of this but he ran out of time.

    As we run out of time, some clever person will figure out to use CO2 as a resource.

    I have some General Atomics, Inc. and other papers on the particulars if anyone is interested.

    John L. McCormick

16. #16 Bocco

    2008/01/28

    It doesn’t cost more energy to sequestrate CO2 than can be produced by burning the fuel in the first place. Take for instance a fully integrated gas fired combined cycle power station. You can get a 55-58% efficiciency from gas to electricity (depending who you ask). This is without sequestration. If you want to do capture and prepare the CO2 for sequestration (which means making it rather concentrated and high pressure 100-200 bar) then it going to hit your efficiency, dropping to 40-47% depending on what kind of technology you use to do the capture. So yes you have to use more fuel to capture the CO2, you emit much less CO2 than if you burned this extra fuel too, but no it isn’t a negative energy balance. I may have misinterpretted your post, and if I have I apologise.

    As for the SOx and NOx removal – that’s something that already has to be done now (at least in Europe) so that’s all priced in. If we all were prepared to pay twice as much for our energy then WE can buy our way out of this mess. That requires that governments put a price on CO2 emissions and set standards for CO2 sequestration credits. Apparently the EU will be presenting such plans within a week.

    If you are looking for details of the CO2 capture technologies then here are some keywords for you: pre-combustion decarbonisation, post-combustion decarbonisation and oxyfuel combustion. Post combustion is the technology most likely to be used in the near future. The same technology is used for purifying H2 for ammonia production, and removing CO2 for natural gas deposits – but beware power production is a larger energy endeavor than refining, so there needs to be some scaling up done.

    Just last week there was a big meeting of four large european projects in Lyon to talk about the different technologies. Look up the projects: CASTOR, ENCAP, CACHET and DYNAMIS for some more information – they all have easily findable websites. The wiki pages are OK, but most seem to have been written by an oxyfuel enthousiast.

    If you want to know about some sequestering projects that are working at the moment then your keyword are: Weyburn (enhanced oil recovery), In Salah (CO2 sequestration from natural gas), Sleipner (CO2 seuqestration in the North Sea) and K12B (CO2 sequestration in a gas field that is still producing). That should get you started.

    The only way to use CO2 as a chemical resource in to put in energy, so it ain’t going to happen. CO2 needs to be put in the ground, and that’s even if we do our best to improve efficiency and ramp up renewable energy.

    Bocco.

17. #17 John McCormick

    2008/01/28

    Bocco, you said,

    [As for the SOx and NOx removal - that's something that already has to be done now (at least in Europe) so that's all priced in.]

    I am not as interested removal cost as I am the increased power required to accomplish pollution control, CCS and plant operation. It still looks like 1.4 units of generator output to feed one unit of electricity into the grid. MORE FUEL. MORE CO2.

18. #18 Bocco

    2008/01/28

    OK, I get what you are saying. Yes more fuel for the same amount of power. And yes more CO2 per unit of power produced, but the CO2 will be sequestrated – all the technologies mentioned above are looking at 80-99% capture and sequestration. Sequestrated CO2 will not add to CO2 in the atmosphere (sorry to be so simple). Whether sequestration will work in the long term remains to be seen, but what I’ve read about the CASTOR project, things look good, although each location will require the same kind of study as now goes into discovering new gas and oil fields. The good thing is that all (or most) the technology, equipment and methods for this exist. It would also seem that the best places are deep aquifers covered by salt layers, as these salt layers are self healing.

    The technologies that are being explored now are second generation technolgies, where the idea is too decrease this energy penalty and the costs, both roughly by half. The current generation of technologies require scaling up from the 50-100MW to the GW scale. And in the future a third generation of technologies will address even more saving, and possibly even coupling of SOx and CO2 removal. I think the problem is lead time – getting post combustion working on an IGCC is still going to take a few years (look at the DYNAMIS time line). The 2 yrs mentioned above is very optimistic. I can’t see any second generation demos getting of the ground at least for 10 or so years. It’s not that we couldn’t do it today, it’s just that without any “financial stick” no donkey’s going to go for a 40 year lifetime 1st generation tech if after 15 years they get priced out of the market by 2nd generation tech. Remember power stations are put up for a long long time.

    If all the current coal fired plant in Europe were replaced by IGCC, then we’d easily reach our Kyoto targets. I’m not saying that Kyoto is anything worth writing home about, it’s just the first few % of the step in the right direction – if we can’t even achieve that….

    Bocco.