New Process Takes Energy From Coal Without Burning It 365
rtoz writes "Ohio State students have come up with a scaled-down version of a power plant combustion system with a unique experimental design--one that chemically converts coal to heat while capturing 99 percent of the carbon dioxide produced in the reaction. Typical coal-fired power plants burn coal to heat water to make steam, which turns the turbines that produce electricity. In chemical looping, the coal isn't burned with fire, but instead chemically combusted in a sealed chamber so that it doesn't pollute the air. This new technology, called coal-direct chemical looping, was pioneered by Liang-Shih Fan, professor of chemical and biomolecular engineering and director of Ohio State's Clean Coal Research Laboratory."
You keep using that word... (Score:4, Informative)
Verb
1. Consume by fire.
2. Be consumed by fire.
No emission-less (Score:5, Informative)
Its not emission-less. If you read his presentation from 2008 you'll see that the C02 is the byproduct of the reaction that is is used to transfer heat to the steam boiler. The C02 still gets generated as before, just now it can be more readily sequestered - assuming that you want to spend the money on that part of the equation.
Coal Direct Chemical Looping Retrofit for Pulverized Coal-fired Power Plants with In-Situ CO2 Capture [doe.gov] (PDF - but why the hell in this day and age do I need t tell you that? Can't you just look at the link?)
Re:Um, WHY? (Score:5, Informative)
There is no burning. Apparently that is the key innovation. The chemical reaction between the coal dust and the rust pellets releases the CO2 in a very controlled manner with the CO2 being separated cleanly rather than mixed up with smoke aka carbon molecules. That must make the CO2 capture much much easier.
Re:Um, WHY? (Score:3, Informative)
Coal is oxidized to produce CO2 and heat. That's "burning", regardless of whether you use air or iron oxides as the oxidizer.
Re:You keep using that word... (Score:5, Informative)
A better word might have been "oxidized" but the good professor probably was trying not to confuse the journalism major
who wrote the story with words too big for their tiny world view.
Lots of CO2 is produced, but it is retained in the chamber and captured, and oxygen and coal are fed in continuously.
They operated it for 9 days straight.
RTFA-ing is the Key! (Score:5, Informative)
The researchers are about to take their technology to the next level: a larger-scale pilot plant is under construction at the U.S. Department of Energy's National Carbon Capture Center in Wilsonville, AL. Set to begin operations in late 2013, that plant will produce 250 thermal kilowatts using syngas.
From 25 kw to 250kw
Sounds like they're scaling it up.
Re:Scaling is the Key! (Score:4, Informative)
Sounds nice, except for the 'combusted in a sealed chamber' bit. How is this going to scale up so they can feed 100 tons/hr through the plant cycle? That is the question.
The key to the technology is the use of tiny metal beads to carry oxygen to the fuel to spur the chemical reaction. For CDCL, the fuel is coal that’s been ground into a powder, and the metal beads are made of iron oxide composites. The coal particles are about 100 micrometers across—about the diameter of a human hair—and the iron beads are larger, about 1.5-2 millimeters across. Chung likened the two different sizes to talcum powder and ice cream sprinkles, though the mix is not nearly so colorful.
The coal and iron oxide are heated to high temperatures, where the materials react with each other. Carbon from the coal binds with the oxygen from the iron oxide and creates carbon dioxide, which rises into a chamber where it is captured.
They ran this for 9 days straight. They only stopped because they were tired. Scaling it up probably is not that much of a problem.
The bigger problem might be obtaining both the fuel and the oxidizers in quantity economically.
Coal powered that finely would be rather dangerous, because it has so much surface area. Exposure to air, any spark could set it
off. Handling it would require special care never to let it flow around or accumulate around the crushers. They might have to
make it in a slurry just for safety, then waste more heat drying it before use.
TFA shows them handling bottles of it, and even then they are wearing masks.
Re:Um, WHY? (Score:5, Informative)
Why not just burn coal and air in an oven and capture the CO2
Because only part of the air gets converted to CO2. Most of the air is nitrogen, and only ~21% is oxygen. Even if you have complete conversion of the oxygen to CO2 (not going to happen), you'd end up with exhaust gas that's mostly nitrogen with some carbon dioxide mixed in. This nitrogen/carbon dioxide mix is difficult to deal with. To do anything with the CO2 you'd have to separate it from the nitrogen and residual oxygen, which gets complicated and expensive.
The hard part is surely the CO2 capture, not the burning.
Exactly. This new method attempts solve that by separating the CO2 generation stage from the air-using stage. If you could effectively separate them, you'll get a pure CO2 stream in one half of the reactor (which if you can keep closed you can pump off into storage tanks) and you'll keep the nitrogen/depleted-oxygen mix in the other half of the reactor, away from your pure CO2.
The way it works is to use iron oxide as an oxygen shuttle. The iron oxide pellets grab oxygen from the air half of the reactor, and are then transferred as a relatively gas-free solid to the coal half of the reactor, where they give up their oxygen to produce a relatively pure stream of CO2. The pellets are then separated from the coal ash and transferred as a relatively gas-free solid back to the air half of the reactor, where they are recharged with oxygen. If you engineer it right, you could conceivably make it a continuous feed operation, where you shuttle the iron oxide beads back and forth through airlocks, keeping most of the CO2 in the sealed reactor where it can be pumped off as a comparatively pure gas.
Comment removed (Score:4, Informative)
Re:Scaling is the Key! (Score:5, Informative)
You are forgetting the other part of the reaction. Air is 78% Nitrogen and 21% Oxygen. In this reaction the Iron removes the Oxygen from the air before it gets into the reactor. So no Nitrogen in the reactor means NOx and no Nitrogen gas to remove from the waste stream.
Re:Scaling is the Key! (Score:4, Informative)
Sequestering CO2 is easy. You just don't have a clue how it works. The CO2 is pumped into abandon oil fields at VERY high pressures. This actually results in a return of the field to oil production, as the CO2 forces out more oil. The hydrostatic pressure at that depth is so great that it forces the CO2 into its liquid form. It's not going to suddenly escape to the surfaces, it's miles down and under unfathomable pressure. If we had an earthquake strong enough to crack that, we'd have far more to worry about. Like the really nasty gasses getting released from natural fissures or the earth splitting asunder.
Re:Efficiency is the key flaw (Score:5, Informative)
It's 2.5% less efficient than a normal coat power station.
Normal plant: 36.43%
This thing: 33.93%
It actually produces 10% more power from the turbine, but the supporting pumps, fans and compressors need to be powered.
Re:RTFA-ing is the Key! (Score:5, Informative)
Re:Scaling is the Key! (Score:5, Informative)
Coal powered that finely would be rather dangerous, because it has so much surface area. Exposure to air, any spark could set it off.
Uh, yoohoo, over here! [wikipedia.org] They already use coal dust in existing coal burning power plants. I think they have the processing handling issues down for that bit. And, there hasn't been a major coal dust accident since 1962.
BTW, for those that trashed my 'we need to stop burning stuff' [slashdot.org] comments regarding how we generate energy. THIS is exactly what I meant. Applause for the researchers. If this does scale and proves out, they should get a Nobel for it!
'Nuf said.
Re:Um, WHY? (Score:5, Informative)
Coal is oxidized to produce CO2 and heat. That's "burning", regardless of whether you use air or iron oxides as the oxidizer.
Ummm, sorry, I'm gonna have to go with the Ph.D. in Chemistry [ohio-state.edu] on this one buddy, and he says it's NOT burning. I would not call your comment, Informative. Uninformed, but not informative. Ooo, that's a t-shirt right there...
Re:Pure oxygen.. (Score:5, Informative)
I emailed the authors after I wrote that and they emailed me back quickly. They said the only NOx comes from the Nitrogen in the Coal. None is produced in the combustion of Iron.
This would significantly lower the scrubbing requirements and cost.
Actually capturing is the key (Score:5, Informative)
Actually capturing is the key. A carbon capturing plant is always going to be less efficient than a non-capturing plant. Try looking at it this way:
36.43% Non-capturing plant
29.14% Post-combustion capturing plant (36.43/1.25)
33.93% This thing
Re:Scaling is the Key! (Score:3, Informative)
Better to put the CO2 into a stable form rather than just 'another place'.
Re:Scaling is the Key! (Score:5, Informative)
It's not going to suddenly escape to the surfaces, it's miles down and under unfathomable pressure. If we had an earthquake strong enough to crack that, we'd have far more to worry about.
If you think that nothing could happen, read about Lake Nyos disaster [wikipedia.org].
Re:Scaling is the Key! (Score:4, Informative)
As this is chemical, and not combustion, (yes yes, sealed chamber...) it should not take up as nearly as much land as required by current plants. Also, just think of all the job creation all those small power plants will require!!!
Any chemist will tell you that combustion is a chemical reaction. What's interesting about this process is that oxidized iron is used to provide oxygen to "burn" the coal instead of injecting air into the combustion chamber. Not using air lowers the overall gaseous output you need to deal with and the output is a bit cleaner as you don't have to scrub some of the crap like NOX out. You still get sulfur compounds and the heavy metals you'd see with traditional burning.