Most methods being studied to "clean" coal fall under the loose heading of "carbon capture and storage," or CCS, which involves stripping the CO2 out of the coal-burning or gasifying process and piping it deep underground. Studies have concluded that CCS is the critical technology needed to reduce CO2 emissions by greater amounts while continuing to allow coal to meet the world's energy needs.

Carbon capture occurs at three points. Pre-combustion: When coal is gasified before it's burned, an almost pure stream of carbon dioxide is created, mixed in and pumped out. The best-known method in this category is Integrated Gasification Combined Cycle, or IGCC, in which gasified coal is used to run a turbine to produce power. This increases efficiency – because it takes more energy to fuel this operation, where heat from this process is captured as steam and used to create more power.

IGCC is used in industrial processes today, but the problem is - CO2 is not contained. Why? There are no penalties for releasing CO2 into the atmosphere in the U.S. However, some companies say they have plans to try and change that.

Other research has focused on trying to strip the CO2 from the gas that remains after coal is burned.
One other technology, called oxy-fuel, can be deployed during the actual combustion process. That involves burning coal in a mix of carbon dioxide, water vapor, and pure oxygen, and eliminates difficult processes for separating the end CO2 from other substances. As of last year one plant in Germany was the first to begin operating using this process. It provides power for roughly 1,000 homes. Waste CO2 is compressed, transported and buried two miles below a depleted gas field.

Putting CO2 underground helps force remaining liquids, like oil, to the surface. Selling captured CO2 to oil and gas field operators, can help recoup some of the companies' investment in CCS technology. One plant in Norway, and one in North Dakota, are using this method.

Under the Department of Energy's cover, seven regional partnerships have been working on the storage issue in the U.S., locating where the geology is favorable for holding massive amounts of CO2. According to DOE, it would take hundreds of years to fill up all the underground space it considers suitable for permanent CO2 storage.

CO2 storage will never be geologically fail proof, the regulatory and legal structure in dealing with liability matters must be secured prior to any proposal that might sway public acceptance. The Environmental Protection Agency is in the process of finalizing rules that cover underground injection of CO2 that would regulate site selection, monitoring procedures, well construction, insurance requirements, and other steps in the process. Transporting CO2 to storage sites could require, as one observer put it, the underground equivalent of "the highway system on steroids."

Storage sites for carbon dioxide draw as much ire as the Yucca Mountain, a proposed nuclear waste site in Nevada continually blocked by lawsuits, since CO2 is less hazardous. However, in 1986, 1,746 Cameroon villagers suffocated in their sleep when a large cloud of naturally-occurring carbon dioxide that was at the bottom of a lake erupted and covered the countryside.

It's clear that some CCS technology is far enough along to place into practice at a commercial level, and a few companies are giving it a go. The major drawback though? The practice would cost billions today.
One of coal's greatest selling points is it creates power at much less cost than fossil fuels.

A 2008 study estimated that adding "clean coal" technology would increase capital cost of a power plant by 50 percent – not including added costs for transporting and storing the captured CO2 or other operating costs.

The study showed, compared to a "normal" power plant, CCS adds four additional costs. Included are capturing equipment would need to be installed, creating more cost, the capture process needs to be powered, a transport system needs to be built and, CO2 needs to be stored. All these steps would require additional capital investment and operating cost. Say billions, and in a poor economy.
The cap-and-trade system that President Obama favored during his campaign would impose limits on emissions that tighten over time and would further require companies to buy and sell allowances to meet the target goals.

Obama has committed to pushing for "cap-and-trade programs to reduce greenhouse gas emissions 80 percent by 2050." Also, his web-site promoted investment in "clean coal." "Obama’s Department of Energy will enter into public private partnerships to develop five “first-of-a-kind” commercial scale coal-fired plants with clean carbon capture and sequestration technology."

Chairman of the House Energy and Natural Resources committee Rep. Henry Waxman has vowed to pass a cap-and-trade bill out of his committee by Memorial Day. Some in the industry are tossing in ideas along similar lines. The detailed plan of the U.S. Climate Action Partnership (USCAP), the entity of two years of research and negotiations, also contains financial incentives for the first commercial coal plants to use CCS, would requiring any coal plant allowed after 2014 to emit a maximum of half the CO2 today. This idea helps to subsidize CCS until caps are strict enough, companies can no longer afford to emit CO2.

The idea being, electric utilities and coal-burners may find it less costly to invest in "clean coal" plants rather than pay costly penalties for emitting CO2.

Many environmental activists believe that removing carbon dioxide out of coal doesn't do enough to address remaining problems like mountaintop removal from blasting, just to retrieve coal, and huge amounts of debris being dumped into valleys and streams.

A major blow to “clean” was dealt just before Christmas when 5.4 million cubic yards of toxic coal ash from a coal-burning plant crashed through a retaining wall, flooding a residential area in the Tennessee Valley. The ash which was contaminated with heavy metals and other toxic substances, forced residents to evacuate, destroyed homes and left toxins that will take months to clean up.

Critics believe, coal will never be "clean," and pursuing that fantasy will take precious time, technology and money away from developing renewable sources of "cleaner" energy. I believe they make a very valid point. Oh, and let us not forget the massive number of jobs realistically created, and the many other beneficial factors that will come from “clean” energy.