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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."
I love reasons! Care to share?
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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just build it bigger!
Or if that can't be done economically, just build millions of little ones!
Oh that's not economically feasible either because each one requires a lot of labor to build? Hmm.... *thinks*
Ok let's just forget about the whole thing and go nuclear.
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.
Maybe we should start burning C-level executives instead of coal.
Sequestering CO2 is not simple, and is currently done mostly by pumping it into used oil fields. It's not certain whether these costs were factored in.
Sequestering it is a lot simpler if you can simply draw if off the top of the CLOSED chamber rather than trying to scrub it out of the stack.
You've got half the battle won already.
What to do with it long term is another problem. But its a problem you would have anyway, so having the CO2 handed to you all
contained is better than where we are today.
Besides coal ash, it appears CO2 is the only by-produce that is not recycled back into the feed-stock.
But, hey, Clean Coal stories have to be knocked down immediately. We can't have it prove even partially successful under any /rollseyes.
circumstance.
Sig Battery depleted. Reverting to safe mode.
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.
RTFA, the process is designed to work with two of the already commonly available forms of fuel to power companies, crushed coal and coal derived syngas.
Two of my imaginary friends reproduced once
It wouldn't work, anyways. Bullshit has a lower energy density than coal.
"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety."
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! 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' 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.