Promising technology Wilsonville plant to test new mercury technology
A power plant near Wilsonville will be the nation’s first to use technology aimed at reducing the amount of mercury it releases into the air.
The E.C. Gaston generation plant, owned by Alabama Power, was chosen by the U.S. Department of Energy to continue testing a new mercury control process first started at the plant in 2001.
The year-long test will determine efficiency, effectiveness and potential costs for the technology. The DOE will fund more than half of the $2.1 million project.
The U.S. Environmental Protection Agency announced in Dec. 2000 its plans to regulate power plant emissions of mercury, which at high doses can cause damage to the brain and senses.
&uot;This technology we’re testing at Gaston is really the most promising technology for mercury control that I’ve seen tested,&uot; said Dr. Larry Monroe, a research scientist for Southern Company, the parent company of Alabama Power.
&uot;This testing is the first in the country, and it received not only national, but international interest.&uot;
Coal fired plants, like Gaston, produce electricity by burning coal to create steam, which is used to turn generators. Mercury, a naturally occurring element, exists in small amounts in coal. When coal is burned, some of that mercury is released through the plant’s stack.
The EPA names coal-burning electric utilities as the biggest source of mercury emissions to the air in the U.S., although the actual level of mercury exposure in humans due to power plant emissions has not been established.
Initial tests at Gaston reduced mercury emissions by nearly 80 percent over a five-day period, Monroe said.
The results were so promising, the DOE agreed to partially fund a year-round test to determine how the process will work on a larger scale over an entire year.
Alabama Power representatives said they hope to begin the tests in the next few weeks while the EPA is expected to propose regulations on mercury emissions from coal-fired utilities by the end of the year.
Mercury and the Environment
In a report published to Congress in 1998 focusing on air toxics emissions from power plants, the EPA identified mercury as the toxic of &uot;greatest concern.&uot;
Mercury is thought to have little or no impact on humans through the air, but becomes dangerous to humans when converted to the organic form after entering the water supply.
When mercury from the atmosphere settles into water sources it can bioaccumulate in aquatic wildlife, especially fish, in a form called methylmercury.
Methylmercury is primarily a threat for pregnant mothers, Monroe said, as it seems to have the most significant impact on developing fetuses.
High doses of mercury to sensitive populations can impede brain development and cause neurological damage to unborn fetuses, he said.
One of the worst documented cases of mercury poisoning occurred in Minamata Bay, Japan, where a chemical company poured tons of mercury compounds into the bay during the 1950s.
Hundreds died after eating contaminated fish and as many as 20,000 are thought to have suffered from mercury poisoning causing neurological damage and birth defects.
However, mercury released from power plant stacks enters the atmosphere in a nonorganic form and is not directly deposited into the water supply. Whether it is deposited locally or travels great distances is still being researched.
There are currently no fish consumption advisories for mercury contamination in any Shelby County waters, according to the Alabama Department of Public Health.
Plant Gaston burned more than 10 billion pounds of coal in 2001 releasing through its stack an estimated 870.5 pounds of mercury, according to Toxic Release Inventory reports.
Southern Company representatives point out that mercury is released into the air by both human and natural sources.
Volcanoes, oceans, soils, gold mining, waste incineration and fossil fuel combustion all release mercury into the atmosphere, Monroe said.
The shiny metal is a liquid at room temperature, and is commonly used in thermometers, batteries, fungicides and dental fillings.
&uot;U.S. electric utilities account for only about one percent of all airborne mercury emissions&045; manmade and natural&045; in the world,&uot; said Sandi Robinson, a spokesperson for Alabama Power.
Cleaning the Air
The mercury control system that will be tested at Plant Gaston was developed by a Colorado-based environmental technology and chemical company, ADA-Environmental Solutions, a subsidiary of Earth Sciences Inc.
The Wilsonville plant was selected to house the test by DOE’s National Energy Technology Labratory because of a unique combination of control systems already in place there.
Gaston is one of only a couple of plants in the nation to use both an electrostatic precipitator and compact hybrid particulate collector (COHPAC).
The COHPAC filters work by collecting pollutants in a &uot;baghouse&uot; where long fabric filters are used to catch fine particulate.
The COHPAC technology was developed by Hamon Research-Cottrell.
The new technology being tested at Plant Gaston includes the use of injected carbon between the baghouse and electrostatic precipitator.
The activated carbon works similar to a sponge, absorbing mercury that is released from the burning coal, Monroe said.
The process is called TOXECON and is patented by the Electric Power Research Institute.
Alabama Power and Southern Company will work with ADA-ES, EPRI, Allegheny Energy, Arch Coal Inc., FirstEnergy, Hamon Research-Cottrell, Ontario Power Generation and TVA.
The DOE will fund 55 percent of the $2.1 million project with the remaining 45 percent funded by Alabama Power and other participating companies
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