Coal has a long history as a dirty fuel, which from the outset of it’s heavy use at the outset of the Industrial Revolution has exacted a heavy cost on human health. Gradually, as coal furnaces became more and more effective, toxic gases and other products were efficiently trapped, and the heavier ashes were routinely separated into several usable sub-fractions. Some of these are now being processed to obtain specific products for sale. Currently the trapping of ashes and their partial conversion into usable products for resale has had the effect of reducing the amount of ash that goes into storage by about 40 percent. Total storage needs can be considerably decreased if the conversion of ashes into usable products for resale is undertaken at all sites where power plants generate ash, and further if strategies are undertaken to remove and use both toxic metals and strategic rare earth metals from some ashes. Overall, the use of coal ash in the manufacture of alumina, silicates, cements, numerous toxic metals as well as rare earth elements is key to the continued use of coal. Rare earth elements have many strategic uses. As a result of their rare occurrence, these elements garner increasing prices in world markets. It is likely that rare earth elements can be as effectively mined from coal ash as they can be from natural sources. By processing nearly all of the ashes produced at coal fired plants the amount of ash by-producets that will need to be disposed of may be reduced to perhaps 20 percent of the amount of ash we currently have to deal with.
To put this in perspective, if in fact we currently process as much as 40 percent of coal ash, then by advancing to 80 percent, but importantly with removal of all toxic metals and rare earth elements, then we could gradually reduce the amount of ash that has to be buried or stored by a substantial amount. More importantly, all, or nearly all, of the toxic metals will have been reduced to trace amounts. If we assume the use of coal as an energy generating fuel remains at its current level, that would mean that the 140 million tons of ash generated from the burning of coal per year would be reduced to about 30 tons. More importantly, it will have been stripped of almost all of it’s highly toxic components. Thus, the threat to the environment going forward is highly reduced. Indeed, it is like going from a highly difficult threat to one which is like no threat at all. Once these measures in handling coal ashes are routinely in place we can go back and recapture the coal ash stored in the most dangerous of the 1100 sites in the country where it is placed currently. We would start with 100 or more of the the most toxic sites first and then deal with the others subsequently and in due course.
In my mind, the above strategy represents a reasonable plan going forward to deal with the toxic ash waste coming from coal fired power plants. Without implementing something like this the future of coal is doomed. People are not going to tolerate even “accidental” spills and the costs associated with clean up. As the costs of generating energies from renewable sources continues to decline it is likely that within a decade or two, most nations will convert to alternative and less costly renewable strategies for power generation. As things are at present, the toxic ash problems associated with coal fired power generation will accelerate it’s demise as a form of energy generation. While carbon dioxide release into the environment as well as toxic gases are still released at some plants not yet modernized, these problems still dim in comparison to the problems of mountains of toxic ash. Further, these problems are magnified, and the urgency of doing something about ash toxicity and storage are increased, by the serious ash spills from storage sites that occurred in Tennessee in 2008 and in North Carolina only recently in 2014.
The remaining problem is the enormous amounts of carbon dioxide that are released into the atmosphere if we continue to burn coal at the current rate. Indeed, the carbon dioxide can be routinely sequestered (liquified) and and stored. Although carbon dioxide is a terminal oxidation product for carbon the carbon dioxide still has a number of uses. It can be also be incorporated into stable carbonates that can be used as components of building materials. Some of it can also be used to stimulate and accelerate the growth of plants, especially to stimulate small trees in enclosed environments to provide starter shoots to be used in more extensive reforestation projects. Liquified carbon dioxide can also be used as a solvent in industrial scale chemistry, which may become a stimulated field in the event that liquified carbon dioxide were to become available free of charge. Nevertheless, with all these uses some of the liquified carbon dioxide would likely evaporate more rapidly than if it were simply stored as a liquid in side by side tanks or in enclosed pressurized locations underground.
There are other issues to consider, but these seem minor. Some coal is partially combusted to drive out gases and produce incompletely oxidized carbon products that are then used in the pharmaceutical and other chemically based industries. Some of the same or similar products are generated from petroleum. Also, some coals are used to make liquified natural gas which is used as cleaner fuel. Such uses would likely be balanced out as we go forward if the major issues of dealing with the substantial amounts of toxic coal ash is considered, and if most of the carbon dioxide and toxic effluents currently released into the air are reduced to near zero.
Proceeding in the manner considered here it is possible the coal industry can help move us forward in a useful way, but without change it is likely doomed to obsolescence within a few decades. Such a fate is accelerated by the continued release of toxic and environmentally damaging effluents into the atmosphere and by the potentially extreme difficulties associated with the accidental released of toxic coal ash into rivers and streams.