Introduction to Clean Coal Technology - meet the future!

[w¡n9Nµ7 §£@¥€r 123]

When coal burns, it releases carbon dioxide and other emissions in flue gas, the billowing clouds you see pouring out of smoke stacks. Some clean coal technologies purify the coal before it burns. One type of coal preparation, coal washing, removes unwanted minerals by mixing crushed coal with a liquid and allowing the impurities to separate and settle.

Other systems control the coal burn to minimize emissions of sulfur dioxide, nitrogen oxides and particulates. Wet scrubbers, or flue gas desulphurization systems, remove sulfur dioxide, a major cause of acid rain, by spraying flue gas with limestone and water. The mixture reacts with the sulfur dioxide to form synthetic gypsum, a component of sheetrock.

Low-NOx (nitrogen oxide) burners reduce the creation of nitrogen oxides, a cause of ground-level ozone, by restricting oxygen and manipulating the combustion process. Electrostatic precipitators remove particulates that aggravate asthma and cause respiratory ailments by charging particles with an electrical field and then capturing them on collection plates.

Gasification avoids burning coal altogether. With Integrated Gasification Combined Cycle (IGCC) systems, steam and hot pressurized air or oxygen combine with coal in a reaction that forces carbon molecules apart. The resulting syngas, a mixture of carbon monoxide and hydrogen, is then cleaned and burned in a gas turbine to make electricity. The heat energy from the gas turbine also powers a steam turbine. Since IGCC power plants create two forms of energy, they have the potential to reach a fuel efficiency of 50 percent. ­

Carbon capture and storage -- perhaps the most promising clean coal technology -- catches and sequesters carbon dioxide (CO2) emissions from stationary sources like power plants. Since CO2 contributes to global warming, reducing its release into the atmosphere has become a major international concern.

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After capture, secure containers sequester the collected CO2 to prevent or stall its reentry into the atmosphere. The two storage options, geologic and oceanic, must contain the CO2 until peak emissions subside hundreds of years from now. Geologic storage involves injecting CO2 into the earth. Depleted oil or gas fields and deep saline aquifers safely contain CO2 while unminable coal seams absorb it. A process called enhanced oil recovery already uses CO2 to maintain pressure and improve extraction in oil reservoirs.

Ocean storage, a technology still in its early stages, involves injecting liquid CO2 into waters 500 to 3,000 meters deep, where it dissolves under pressure. However, this method would slightly decrease pH and potentially harm marine habitats. All forms of CO2 storage require careful preparation and monitoring to avoid creating environmental problems that outweigh the benefits of CO2 containment.

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Cleaning coal and sequestering its emissions significantly raises the per-BT­U price of what would otherwise be an inexpensive fuel. While selling byproducts like gypsum or commercial CO2­ for sodas and dry ice can offset the price of clean coal technologies, a charge on carbon could make emission-reduction financially realistic.

http://science.howstuffworks.com/clean-coal.htm/printable

[Trumplestiltskin 5,791]

There's not really any such thing as "clean" coal.

[w¡n9Nµ7 §£@¥€r 123]

There's not really any such thing as "clean" coal.

Cleaner, if not clean.

I recommend you read the article, the technology behind it is very interesting!

[Trumplestiltskin 5,791]

There's not really any such thing as "clean" coal.

Cleaner, if not clean.

I get that - but people conveniently forget where it is that the coal comes from. Getting it out of the ground and transporting it cross-country is a filthy business.

[w¡n9Nµ7 §£@¥€r 123]

There's not really any such thing as "clean" coal.

Cleaner, if not clean.

I get that - but people conveniently forget where it is that the coal comes from. Getting it out of the ground and transporting it cross-country is a filthy business.

It doesn't have to be. See gasification.

[w¡n9Nµ7 §£@¥€r 123]

Here is what the organization Friends of the Earth thinks about clean coal:

What is FOE's position on clean coal?

As long as Clean Coal includes Carbon Capture and Storage (CCS) we would be like to see demonstration projects. Clean Coal without CCS is approximately 20% more efficient than existing coal technology. However, without CCS it is still nearly twice as polluting as gas fired power stations and possibly three times as much as Combined Heat and Power plants (CHP). However, Clean Coal WITH CCS can capture 85-90% of the gases emitted, but this still needs demonstrating at large scale.

FOE would like to see a few clean Clean Coal with CCS demonstration schemes, preferably on industrial sites with good CHP potential. Therefore, the benefits of CHP and carbon capture are combined - both would be capable of sharing the same CO2 pipeline and the heat from the power station. A really well designed demonstration scheme on an industrial site could share the CO2 pipeline to an oil field in the North Sea (where the CO2 would be stored) and provide heat from the power station to nearby industrial processes. Hot water from the power station could then be usefully used by local industry.

Is this a better option than renewables?

No, but it could have a supporting role for our interim energy needs. If viable, it could be complementary to renewables in achieving substantial CO2 emission reduction in the short term. It could also potentially be useful in the transition to a low carbon economy based on renewable power over the next decade. Additionally, it could certainly avoid any new nuclear programme as Clean Coal would provide base load generation.

[Trumplestiltskin 5,791]

That's the problem right there - carbon capture technology for coal-fired plants hasn't yet been implemented on a commercial scale. Its still a ways off in other words.

As to gasification - you still have to dig the stuff out of the ground don't you?

[w¡n9Nµ7 §£@¥€r 123]

What's the problem with digging it out if the pollutants can be controlled?

[Nessa 23]

u guys worry too much about the environment. the world is gonna end in 4 years, who cares?

[Trumplestiltskin 5,791]

What's the problem with digging it out if the pollutants can be controlled?

I get that its cleaner at the point of combustion - but as I said it feeds a certain misconception that the technology is environmentally friendly when it involves strip-mining of the environment and a massive network of transportation logistics. Neither of the secondary activities are particularly green.

[Hilarious Clinton 452]

Clean coal rox!

[almaty 19]

i agree...help out allot fo laid-off miners in my home area

[w¡n9Nµ7 §£@¥€r 123]

Agreed.... clean coal FTW!!!

[Saddle Bronc 124]

Since the cleanest coal in North America comes from AB--bonanza for "my" province!

[Kevin and Guitar 0]

Clean coal? I'd like to see it happen if it is actually possible. Not for our nation, but for coal burners like China it might work. Especially if it was cheap and the governments burning coal actually enforced the clean coal process. U.S. companies would do very well if that happened.

For even interim energy, clean coal is not a good road to go down for the U.S. I'd like to see a massive fund should be put together to re-train coal miners in high tech or green energy building.

Coal mining and coal burning in the U.S. is just not feasible for the future. Creating renewable green energy is.