Coal Mining and the Environment: Restored Lands and Clean Air
The nation’s coal industry works to protect the environment by restoring lands after mining and by ensuring that advanced technologies are used at power plants to capture emissions and protect the environment.
Once mining is complete, the mined lands are restored to create rangeland, prime farmland, wildlife refuges, wetlands, or recreation areas. Land restoration requires the collective efforts of engineers, biologists, hydrologists, range scientists, and other environmental experts to return the land to productive use.
How Does Land Restoration Work?
Land restoration—what the industry calls land reclamation—is the process of restoring or improving land after surface mining. U.S. mining companies have reclaimed more than 2.6 million acres of mined land over the last 35 years and have contributed nearly $10 billion for the reclamation of areas mined decades ago before reclamation was a common practice and legal requirement.
First, geologists study rock formations to find coal reserves. Test holes are drilled so that samples of coal can be examined for evidence of quality, quantity, and location beneath the surface.
Before mining ever occurs, a reclamation plan is carefully established and approved by government regulators. This involves studying the area’s geology, plants, water, soil, and wildlife. Information is documented so that the land may be restored to its original state after the mining has been completed. In addition, the mining site is examined for artifacts from past cultures. If any are found, they are removed and preserved based on proper cultural treatment.
Next, the timeline for mining and reclamation is set. Miners work with federal and state government agencies and local officials to ensure that all regulations are being followed.
Once the planning phase has been completed and the required permits have been obtained, mining may begin. The topsoil, subsoil, earth, and rock are removed and set aside, and the coal that lies just below the surface is removed.
During the mining process, water is tested to ensure that it meets proper quality. It can be treated either in ponds which allow sediments to settle or through water treatment systems to ensure good quality is maintained.
Finally, the formerly mined area is filled with the overburden, the earth and rock that were removed earlier and soils. The area is restored to its original condition or improved. This often means planting, seeding, and irrigating the land. Monitoring will continuing over a period of years to ensure the restored land meets the objectives.
To learn more about reclamation of coal mines, please check out the before-and-after photos at http://www.mii.org/reclcoal.html.
Power Generation and Near-Zero Emissions
U.S. coal-fueled electricity generation also meets some of the toughest standards in the world. Over the past four decades, coal-fueled electricity generators have invested as much as $95 billion in advanced emissions technologies. Since 1970, coal use has tripled as emissions such as sulfur dioxide, nitrogen oxides, and particulates have been reduced more than 80 percent per megawatt hour. These results are based on public data.
The next generation of low-carbon and near-zero emissions technologies will continue this progress toward the industry’s ultimate goal of developing technology that produces virtually no emissions.
The path to what is called ‘near-zero’ emissions has three parts: build, demonstrate and deploy. First, build plants that use new clean coal technologies, second, demonstrate their effectiveness, and third, deploy the technologies to other plants in the United States and around the world.
New coal plants are highly efficient, which means they can produce more electricity based on every ton of coal used than older plants. These power plants, which use supercritical technology, produce about one-fifth of the emissions of the current coal fleet. Even carbon dioxide emissions are reduced by as much as 40 percent.
Supercritical coal plants are highly efficient and minimize emissions. In the United States, these plants have one-fifth the regulated emissions rate as the existing coal fleet. Even CO2 emission rates are 15 percent below the existing fleet and more than 40 percent below the oldest plants. To learn more about the plant operations and technologies, view this Supercritical Technology diagram and click on each of the 7 numbers.
Carbon capture and storage (CCS) is a technology that has been used in the oil industry for a half-century to push out more oil from aging oil fields. The technology can be used at power plants to capture of carbon dioxide before it reaches the atmosphere. Also known as carbon sequestration, it captures the carbon dioxide, compresses it, injects it deep underground where it stored permanently. There are currently 80 large-scale carbon capture projects in development around the world. The Obama Administration is calling for at least 10 commercial demonstrations within the next five years, and the International Energy Agency, the world’s premier energy advisor, a is urging governments and the coal industry to accelerate the development of this technology on a commercial scale so that it can be effectively used in the next decade.
Advanced technologies are protecting the environment today, and ongoing research will lead to development of power plants of the future that will almost completely eliminate emissions. Reports from the National Coal Council information tab focus on CCS and are available here.
How Does Clean Coal Technology Work?
Clean coal technology (CCT) is a new generation of energy processes that reduces emissions from coal-based power plants, while increasing efficiency. The Department of Energy is working to advance these technologies. One way is through the Coal Utilization Science program, whose primary emphasis is to support the development of advanced technologies that use coal with near-zero emissions, or those that virtually eliminate emissions of sulfur dioxide, nitrogen oxides, particulates and even carbon dioxide. Click here to learn about other useful CCT-related terms.
These technological advances were conducted to comply with the Clean Air Act, passed in 1970. Additional advances have been made as part of the Clean Coal Technology (CCT) Program, which began in 1985.
How Is Coal Made Cleaner?
While the coal is combusted, technologies can remove more sulfur and nitrogen. Devices called flue gas desulfurization systems, or “scrubbers”, remove more than 90 percent of the sulfur dioxide emissions from power plants. The technology works by essentially spraying the power plant air stream with a mixture of water and lime or limestone, which reacts with the sulfur dioxide. The byproducts can be disposed of or used for road construction, concrete, and drywall. To learn more about coal combustion byproducts, click here.
Another method involves using devices called electrostatic precipitators, which give coal dust particles an electric charge so they can be attracted to a collector plate.
Other methods of removing emissions involve the way the coal is actually combusted. In fluidized bed combustion (FBC), coal is inserted into a bed of particles (including limestone) that are suspended in the air and react with the coal to heat the boiler more cleanly. In FBC, coal is burned at a slightly lower temperature, which helps prevent some nitrogen oxide gases from forming. The result is that FBC can remove more than 90 percent of the sulfur and nitrogen while the coal is burning. Through a chemical reaction, sulfur gases are changed into a dry powder called calcium sulfate, which can be used to make wallboard for building homes.
The coal gasification method changes coal into a gas that heats the way natural gas would. This method can remove up to 99.9 percent of the sulfur and tiny dirt particles from burning coal.
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