TCS Daily


Mercury Matters

By Willie Soon - May 8, 2003 12:00 AM

Our American ways of "life, liberty and the pursuit of happiness" don't just happen magically. They require certain material foundations and supports. Among those, perhaps the most easily taken for granted is our efficient delivery of cheap, abundant energy. For example, in 2000 U.S. power plants provided 3.8 trillion kilo-Watt-hours of electricity meeting steadily rising demands from the commercial, industrial and residential sectors.

Despite this, power plants are often the targets of many ill-considered regulations ostensibly designed to mitigate the world's environmental and climatic problems. But the proposed regulations will likely do more harm than good.

Domestic political efforts are currently underway to reduce mercury emissions from the burning of coal and other fossil fuels in the United States. The concern today is that when coal is burned to generate electricity, the previously latent mercury once locked up in geological reservoirs enters the world's air, water, and soil and has harmful health effects on humans and wildlife.

In order to minimize potential harm, legislation - like the EPA's Clear Skies Act of 2003 (proposing incremental cuts of Hg emission by a total of 69% in year 2018) and the earlier proposed Clean Power Act (proposing reductions of Hg emissions by 90% from the 1999 levels by 2007) - aims to force U.S. power plants to reduce and eliminate their emissions of mercury.

But are these regulations a good idea? To answer that, we need to weigh the likely costs of the regulations against the likely benefits. And given our current best scientific understanding on the global cycling of mercury, forcing restrictions on mercury emissions from U.S. power plants is unwise and may even be dangerous.

The Facts

The first important thing to understand is that exposure to elemental mercury from power plants is not problematic. To become hazardous, elemental mercury first must undergo a complex chain of bio-processing and reprocessing in order to accumulate a sufficiently large dose of the harmful form of mercury called methyl-mercury. The cellulose of algae, tiny water-borne fleas (with names like Daphnia), even the stomachs of chickens convert elemental mercury emitted from power plants and other sources into the toxic form agent known as methyl-mercury.

Next, some perspective is in order (Chart 1). Consider that American power plants are responsible for only 1% of the world's total output of mercury. The rest comes from natural sources like oceans, volcanoes and wildfires (55%), and other non-U.S. man-made sources (42%) like power plants in China, Europe, India, Australia and Zaire.


U.S. power plants emitted about 50 metric tonnes (with one tonne equal to 1000 kg) of Hg into the atmosphere in 2000 while a new study published in the Royal Swedish Academy of Sciences journal Ambio by a group of scientists from Lanzhou University estimated 270 tonnes of Hg were released from coal combustion in China over the same period.

In addition, another major study from the United Nations Economic Commissions for Europe Convention on Long-Range Transboundary Air Pollution found that since 1995 the U.S. emits less mercury than China, India, Australia and Zaire as well as less than the combined total from the top-seven European emitters: Russia, Poland, Ukraine, Czech Republic, Romania, France and Germany (Chart 2). Importantly, mercury emissions from U.S. power plants dropped all through the 1990s (most likely a co-benefit of current scrubber technologies for air pollutants like SOx and NOx).

Furthermore, industrial demands for mercury (and hence emissions) in the U.S. have been systematically and rapidly decreasing over time through common sense public policy controls on mercury content in less essential products like paints, pesticides and batteries.

From a regulatory-efficiency standpoint, the relatively clean U.S. power plants are not the best target for addressing the global mercurial emission problem. Why? We lack the technological know-how to eliminate mercury emissions. An October 2001 U.S. Energy Department's Energy Information Agency report warned that "For many combinations of plant and coal type, existing technology may not be able to achieve ... [The] limit for ... removing 95% of the Hg in coal used by electricity generators today."

As such, the proposed regulations are likely to drive up energy costs significantly. Since the poor and middle class pay a greater percentage of their income on basic energy needs, the heaviest burden of such regulations will fall on those least able to afford them.

A Sensible Way Forward

A January 2003 scientific research paper, funded by the Electric Power Research Institute, reported the rather surprising possibility that vegetation burning worldwide - such as forest fires - emits as much as 850 tonnes of mercury annually. This estimate is consistent with another recent independent research conclusion that between 450 and 1200 tonnes of mercury emissions result from the worldwide burning of vegetation. As such, a more effective mercury controlling policy would be to reduce vegetation burning in the U.S. by promoting better forestry management and stewardship and by encouraging similar efforts around the globe.

Another useful step would be to extinguish fires that have been burning for thousands of years in the world's underground coal mines and fields. Not only do these fires emit considerable amounts of mercury, but they are a wasted potential resource. For example, a team of Dutch scientists recently arrived at the stunning conclusion that China loses about 100 to 200 million tonnes of high quality coal from natural coal burning. This amount is about 5 to 10 times the annual export of Chinese coal. Based on laboratory data on mercury contents in 234 coal samples collected from 14 main coal-producing provinces in China, the burning Chinese coal fires are estimated to contribute about 15 to 30 tonnes of mercury every year. With this wastage rate, the Chinese coal fires will equal the total mercury emission from U.S. power plants in just a few years.

Placing heavier regulatory burdens on already-clean U.S. power plants that will drive up energy prices makes little economic sense. In the face of more realistic and efficient alternatives, it makes little moral or environmental sense as well.
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