4.2 What is Clean Coal? Coal is Solar Energy Stored by Plants Millions of Years Ago. We now have the Technology to “Clean” It.

Unless large new petroleum reserves are discovered, a greater share of our future needs will have to come from coal and from alternative energy sources such as nuclear, geothermal, solar, wind, tidal and hydroelectric power. Two fossil fuel alternatives, oil sands and oil shale, are sometimes mentioned as promising sources of liquid fuels.
Along with oil and natural gas, coal is commonly called a fossil fuel. Such a designation is appropriate because each time we burn coal we are using energy from the Sun that was stored by plants many millions of years ago. We are indeed burning a fossil.

Coal has been an important fuel for centuries. In the 19th and early 20th centuries, cheap and plentiful coal powered the Industrial Revolution. By 1900 coal was providing 90% of the energy used in the United States. Although still important, coal currently accounts for about 22% of the nation’s energy needs.

Until the 1950s, coal was an important domestic heating fuel as well as a power source for industry. However, its direct use in the home has been largely replaced by oil, natural gas, and electricity. These fuels are preferred because they are more readily available, delivered via pipes, tanks, or wiring, and cleaner to use in the home.

Nevertheless, coal remains the major fuel used in power plants to generate electricity, and it is therefore indirectly an important source of energy for our homes. More than 70% of present-day coal usage is for the generation of electricity. As oil reserves gradually diminish in the years to come, the use of coal may increase. Expanded coal production is possible because the world has enormous reserves and the technology to mine coal efficiently. In the United States, coal fields are widespread and contain supplies that should last for hundreds of years.

Although coal is plentiful, its recovery and use present a number of problems. Surface mining can turn the countryside into a scarred wasteland if careful and costly reclamation is not carried out to restore the land. Today all U.S. surface mines must reclaim the land. Although underground mining does not scar the landscape to the same degree, it has been costly in terms of human life and health.

Moreover, underground mining long ago ceased to be a pick-and-shovel operation and is today a highly mechanized and computerized process. Strong Federal safety regulations have made U.S. mining quite safe. However, the hazards of collapsing roofs, gas explosions, and working with heavy equipment remain.

Air pollution has been a major problem associated with the burning of coal. Much coal contains significant quantities of sulfur. When the coal is burned, the sulfur is converted into noxious sulfur oxide gases. Through a series of complex chemical reactions in the atmosphere, the sulfur oxides are converted to sulfuric acid, which then falls to Earth’s surface as rain or snow. This acid precipitation can have adverse ecological effects over widespread areas.

Today, Coal pollution mitigation, sometimes called clean coal, is a series of systems and technologies that seek to mitigate the health and environmental impact of coal, in particular air pollution from coal-fired power stations, and from coal burnt by heavy industry.

The primary focus is on sulfur dioxide (SO2) and nitrogen oxides (NOx), the most important gases which caused acid rain; and particulates which cause visible air pollution, illness and premature deaths.

The National Energy Technology Laboratory has administered various programs which have helped to meet regulatory challenges by incorporating pollution control technologies into a portfolio of cost-effective regulatory compliance options for conventional and developmental coal-fired power plants. This portfolio has positioned the U.S. as a top exporter of clean coal technologies such as those used for SOx, NOx and mercury, and more recently for carbon capture, consistent with a goal of deploying advanced coal-based power systems in commercial service with improved efficiency and environmental performance.

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