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New Process Takes Energy From Coal Without Burning It
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."
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.
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combust:
Verb
1. Consume by fire.
2. Be consumed by fire.
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"New technologies that use fossil fuels should not raise the cost of electricity more than 35 percent, while still capturing more than 90 percent of the resulting carbon dioxide. Based on the current tests with the research-scale plants, Fan and his team believe that they can meet or exceed that requirement"
good luck selling that
How does the lack of pollution from the process compare against that generated from the acquisition of the coal?
Is it possible/practical to convert an existing coal power plant?
Is there an appreciable energy/pollution cost to produce the fine powder coal used in the process?
How much energy is consumed or how much pollution is produced in transporting the coal to the reactor?
Is the process itself efficient in regards to the energy output when compared against the total energy costs?
I'm sure there's a lot of other things that don't spring to mind instantly, but I'm certainly not an expert on any of this. Doubts notwithstanding, this is pretty cool.
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 (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?)
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So it captured 99% of the CO2 in a vessel. Great! Now what does it do with it? Vent it to the atmosphere for zero gain?
Or use some magic zero energy cost process to convert it to chalk or something? Guess the article was missing that.
This is like Sasha Cohen's Hoverboard invention - it's a plank that real scientists can figure out how to levitate. Can I have venture capital?
Maybe they can capture the carbon dioxide, but what are they going to do with it afterwards? Put it in a container and bury it underground? The carbon dioxide will still be there, and the only way to get rid of that is through another reaction, which most likely needs energy to happen.
Another important question is the efficiency. Are they able to produce the same amount of electrical energy from each ton of coal as traditional methods? If their efficiency is worse, then I am very unimpressed. If their efficiency is better, then that may be a more interesting story than that of capturing the carbon dioxide.
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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.
A fool throws a stone into a well and a thousand sages can not remove it.
What Virginia mountains? I don't know what you are talking about, I don't see any....
Coal is oxidized to produce CO2 and heat. That's "burning", regardless of whether you use air or iron oxides as the oxidizer.
We already burn a crap load of coal for our electricity. Wouldn't it be great if we worked to make it clean-er ( at least in terms of soot and mercury released into the air)? There isn't much on the horizon that could replace coal over night. We should try to find something will all due haste, but it wouldn't hurt to get the low hanging fruit. Its pretty much what Obama is doing now and its a sensible approach.
Well.. maybe. Or Maybe not. But Definitely not sort of.
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.
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o0t!
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.
Reading between the lines the difference is you aren't getting air into the reactor. So you don't have to heat and separate the Nitrogen. It says the iron pebbles are exposed to air in the reactor but I don't think that is entirely accurate. I think they are exposed after they give up their oxygen to the carbon and are still hot but outside of the actual reactor. This would provide an easy way to chemical way to separate the oxygen from the nitrogen. So the only gaseous byproduct is pure CO2 not CO2 mixed with Nitrogen which is harder to process.
I could be wrong.
I love Jesus, except for his foreign policy.
I think it is because when you burn in air (Mostly Nitrogen) you create NOx compounds. When you burn your exhaust gas contains lots of nitrogen which you have to remove the CO2 from to process. It seems they are using rust as a way to take the oxygen out of the air first so when it reactions with the carbon you get pure CO2 which can easily be compressed without having to deal with Nitrogen and it's oxides.
I love Jesus, except for his foreign policy.
Except that the United States has the benefit of cheap methane (CNG). Regionally, you also have cheap hydro in the NW and TV, cheap wind in the upper prairie states and cheap solar in the sun belt.
Coal is only cheap when you exclude the environmental and related health costs. The heavy and radioactive metals expelled as particulate matter are a major source of cancer. The nitrogen oxides expelled are a major contributor to acid rain. People are sorta forgetting those issues in the whole CO2 debate. Last I checked, chemotherapy wasn't cheap.
And many areas in the US have restrictions on wood burning. Unless you're talking about a pellet stove with catalytic converter which is fairly darn clean as far as burnin' wood goes as is often exempt from burn restrictions.
Normal coal burning plants could collect all their exhaust as well. It would cost part of their energy output, but not all
The problem is the other gasses after passing through the combustion chamber, which you may not want to pay for compressing and sequestring. The 78% nitrogen in the atmospheric air will still be there after burning and will contribute to the increased cost.
I wonder if the extra cost of pulverizing the carbon to 0.1mm particle size is a proper offset for the CO2 separation cost from air based combustion.
Also, since the oxygen is delivered bound to iron, the total energy generated but this process will be smaller... unless (or "even if"?) you decide to reoxidize the reduced iron by burning it again
Questions raise, answers kill. Raise questions to stay alive.
Not only does the system cost a lot of money, it also produces less power per unit of coal.\
There's also the cost of dealing with the captured CO2 as well. If you don't want to spend even more money storing it somewhere you'll have to let it go. There's also more CO2 to get rid of, because it's a less efficient system.
The iron is not a consumable. It is just used to carry oxygen and is re-used.
The problem I see is its much more expensive and reduces the amount of usable energy in the coal. More coal is consumed. You've captured all the CO2 but you still also need to spend more money to deal with it long term.
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.
Old process (burning):
Inputs: coal, air
Outputs: heat, CO2, N2, N2O
FTFY.
Last I checked, burning is combustion.
Nor do I understand what the hell is advantageous about it. They admit to oxidiation of the hydrocarbons (ie, burning), heating it to high temperature, and the release of CO2 gas. So exactly what is so great about it?
Coal isn't clean though. This would clean up the side of the equation where you're burning it. But, it would do absolutely nothing for the mining aspect of it. Which is a huge mess as it stands. If you want to burn things for energy, you're better off starting with something like trees which are mostly carbon neutral as it is.
Sure, it's technically clean if you ignore the incredible damage that it reeks on the landscape, but it's definitely not clean in a practical sense.
Maybe it will. I haven't read the article but there have already been trials where coal is burnt in-situ via using horizontal drilling and air injection. Apparently that works so long as you have full control of all the air getting in.
Also, (as I keep telling the fanboys here of 1970's nuclear who don't have the merest clue about developments since), there is not really such a thing as a "clean" industrial process - that's just stupid PR. All you can do is aim for less impact so you get a net benefit.
This is nice, we have the opportunity to capture all produced CO2. But what are we going to do with it?
"Conversion of chemical species" is just another term for "reaction", and "production of heat" through a reaction is the same thing as "exothermic", and a shorter term for "chemical reactions between a fuel and an oxidant" is "oxidation". Thus to put it even shorter: combustion is exothermic oxidation.
Chill mate.
My point in reply to PP: "combustion does not require fire"
(as I'm growing old, I don't feel the same geekish urge to be absolutely exact - sometime I don't feel the need of being right)
.
Questions raise, answers kill. Raise questions to stay alive.
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 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...
From TFA:
No other lab has continuously operated a coal-direct chemical looping unit as long as the Ohio State lab did last September. But as doctoral student Elena Chung explained, the experiment could have continued.
“We voluntarily chose to stop the unit. We actually could have run longer, but honestly, it was a mutual decision by Dr. Fan and the students. It was a long and tiring week where we all shared shifts,” she said.
Fan agreed that the nine-day experiment was a success. “In the two years we’ve been running the sub-pilot plants, our CDCL and SCL units have achieved a combined 830 operating hours, which clearly demonstrates the reliability and operability of our design,” he said.
His entire staff of grad students manned the thing and kept feeding it coal for a week and it ran nonstop the whole time, and could have kept going. So this appears to be a solved problem.
Weaselmancer
rediculous.
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.
I love Jesus, except for his foreign policy.
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
It only cleans up the burning side if we have something to do with all that CO2 that this process produces.
For a fuel that requires little or no processing it's extremely energy dense. Ultimately the problem wouldn't be with the process but the budget minded power companies. There's a reason "clean coal" is like bigfoot, largely a myth. Clean coal would cost more money reducing profits. It's the reason the industry doesn't remove mercury and coal dust from the exhaust, reduced profits. They even had a government mandate and the still waited until the deadline and are now saying it's too hard. The process can trap 99% of the CO2, the trick is keeping the power companies from not releasing it into the atmosphere to save money. White Diesel is a great source of fuel and second only to natural gas for being a clean fossil fuel but it involves stripping of the CO2 and you are faced with the same problem. Sequestration isn't as simple as it sounds. Compressing huge amounts of CO2 gas takes energy and the underground storage areas don't tend to be near power plants. When you start burning more coal just to store the CO2 from the last batch the efficiency goes way down. If the existing plants had been positioned and built with all this in mind we wouldn't have all these problems. Now there are no cheap and easy solutions. Personally I prefer using algae or greenhouses to store the CO2. Try this approach, pump the CO2 into large cheap greenhouses that grow Kenaf, it's related to hemp but totally legal and interchangeable with industrial hemp. Use as much as industry needs for fiber and seed oil then turn the rest into biochar, a good one to read up on if you aren't familiar. The char can be mixed with farmland improving the soil and it'll absorb the excess fertilizer reducing run off and reducing the amount needed to grow food. The carbon is stored for thousands of years, if not millions. The power companies get to make extra money off the Kenaf and they greatly reduce the CO2 and mercury released. The Mercury will get trapped in the char and the CO2 will be stored as solid carbon. These days they try to solve everything with technology when mother nature has been doing it for billions of years.
Clean depends on the definition. There is a waste product associated with every kind of industrial process and every kind of energy production. But the forms of the waste are not all the same nor are they equivalent. Many time people equate the term clean to the quantity of carbon produced during the energy production. If this new technology is viable and it actually contains 99% of the carbon that is a HUGE development. The mining process could be improved and much of the eye sore can be avoided if you don't strip mine. I think there is a town in Pennsylvania that has been "on-fire" since the 50s or 60s because an underground coal fire was not contained.
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Hence PR bullshit and a barrier to communication instead of normal language. Just treat such statements as a red flag to indicate that you cannot take the speaker at their word and need a second opinion - the word "clean" is only ever in there to mislead, if it wasn't you'd see "less pollution than X" instead of misleading bullshit.
Of course things can be improved but whenever you see "clean" the objective is to improve the perception instead of the reality. One of the places I visited for work was a power station where water was injected into the exhaust to give it a nice fluffy white "clean" look to impress the people in a nearby town, but the place was no less polluting than more remote power stations that didn't bother. In a truly comical stuffup that trick combined with a scrubber failure one night produced nitric acid fog that condensed on hundreds of cars in the town and cost the power authority a fortune in costs to get them all repainted.
The problem is that the system has changed since the carbon was taken out of the system. Reintroducing it in such massive quantities over such a short period of time changes things too rapidly for species to adapt to.
Methane emissions are a very serious problem as well, but that has fuck all to do with power generation. You can use methane to produce power, but that's got nothing to do with being carbon neutral.
I've always been confused by "Carbon Neutral" propaganda. For example, we have always had the same amount of carbon in the environment. Just over the years it's been sequestered into oil/coal/etc. However, now if it's been out of commission for thousands of years and it's somehow out of the equation. So burning oil/coal/etc is just normalizing the balance.
No, no, no! You missed the biggest sink for carbon. The one that is orders of magnitude greater than all the others put together: limestone (60 million gigatons vs the 720 gigatons in the atmosphere and the 38,000 gigatons in the oceans). If you think that normalizing the balance with all of the carbon that has been taken out of the environment is a good thing, then you must be from Venus.
They just burn it with pure oxygen instead of with air. The innovation, and it is an innovation IMHO, is that they used iron to capture and transfer the oxygen. This prevents the forming of NOx, which is a good thing. ...
This means they can burn the coal hotter without emitting dangerous amounts of NOx.
1. They let iron pellets rust. Or they buy rust in the first place.
2. They put the rust pellets into the chamber with coal dust.
3. They ignite the mixture (this requires a bit more heat than usual burning. At least 1566 ÂC or 2850.8 F)
4. The coal dust pulls the oxygen out of the rust and binds it with the carbon into quite pure CO2.
5. Heat (a lot of it)
6. Use the heat in a default thermoelectric power plant.
7. The pellets can rust again, to capture oxygen.
8.
9. Profit.
If they would combine it with an iron smelting plant then the energy required in step 4 to pull the oxygen out of the rust would not be wasted. Then the iron pellets are one of the end results. Of course, then you'd have to emit step 7.
To me this seems familiar. If I am correct this is the way Thermite works, just with aluminium powder instead of coal dust.
Well, I might have a way, but it only works on a semi spherical planet in a vacuum.