Cement Kiln Mercury Emissions Regulated - In Time For Earth Day!
Rotary Portland cement kiln. Image credit:Wikimedia.
I doubt if any other nation regulates mercury emissions from cement kilns the way USA is about to. USEPA's just-announced progress on this front took a decade of work, several lawsuits by activists, a new EPA Administrator willing to obey the law, and a new Congress that doesn't (yet) bow to lobbyists and interfere with EPA. With all that build-up, the new, final USEPA cement kiln mercury control regulation is indeed a "sea change." More about that down page.Essence of the new regulation.From the EPA press release:-
EPA is proposing to significantly reduce mercury emissions from Portland cement kilns, the fourth-largest source of mercury air emissions in the U.S. The proposal would set the nation’s first limits on mercury emissions from existing Portland cement kilns and would strengthen the limits for new kilns.The final proposed rule, Portland Cement Manufacturing: Proposed Amendments to National Air Toxics Emission Standards is down-loadable from here as a pdf file.
The proposed standards also would set emission limits for total hydrocarbons, particulate matter, and sulfur dioxide from cement kilns of all sizes, and would reduce hydrochloric acid emissions from kilns that are large emitters.
Where does the kiln-emitted mercury come from?Most of the estimated 81% reduction in kiln mercury emissions which will be accomplished by the new rule - a 11,600 pounds or 5,262 Kg/year estimated cutback from kilns - represents a control of inert mercury being distilled from coal combusted to run the cement kilns.
Other sources of mercury in kiln emissions.Industrially-burned natural gas emits a small amount mercury. (Domestically used natural gas has had the mercury scrubbed out.) Mercury may originate from the limestone being processed and also from fly ash, if that is being added.
AnalysisWhen I said this regulation is a "sea change" I meant it figuratively and literally.
Economically and otherwise nutritionally-valuable fish bio-accumulate especially toxic forms of mercury which originate from polluting activities on land: mainly coal burning. This impacts especially apex predators in the sea - the ones that eat the smaller fish that ate the little fish that ate plankton and crustaceans, as dry-fall, direct precipitation, and runoff carry mercury to the seas that surround us.
As time passes, the new EPA regulation will help make both freshwater and coastal marine fish safe to eat. The economic impact of making fish safe to eat once again is all to the positive. Unfortunately, the new rule will not help decontaminate fish imported from other regions of the earth where coal is increasingly burned for electricity.
Mark these words. This rule make it more difficult for coal-fired electrical utilities to compete on price with natural gas-fired electricity and/or renewable energy. How can that be you ask?
Coal-fired electrical generating plants currently send most of their mercury emissions skyward, as vapor carried along with hot gases flowing up the smokestacks. Because mercury is a metal vapor in hot stack gas, it is dissociated from particulate matter and therefore is not captured in conventional pollution control devices like a bag filter. Hence, relatively little mercury ends up in the fly ash produced by utilities. (Mercury does coalesce into aerosols and dust particles down wind from the discharge point.)
If coal-fired utilities are forced by coming regulation to add mercury pollution controls, they are likely to end up diverting a great deal of the captured mercury to the fly ash, increasing the mercury concentration of fly ash, which is commonly added to cement kiln feed. Cement kilns will not be able to serve as de-facto disposal facilities - which amounts to nothing more than shifting the mercury from one stack to another. Thus, utilities that once were giving away fly ash to cement kiln operators will now have to pay to dispose of it instead, increasing the cost of coal-fired electricity.
See the regulatory strategy? Cement kilns first. Then on to fly ash. And, finally, to coal-fired utility boiler emissions.
Still waiting to hear how those "clean coal" plants DOE is supporting with grants plan to manage their mercury and sulfur waste.