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Cook Inletkeeper Energy Program

FREQUENTLY ASKED QUESTIONS:

Coal Mining & Combustion

How does large scale strip mining work? Strip mining is used when the coal seam is relatively close to the surface.  First the topsoil and subsoil are removed by large scrapers.  The topsoil may be moved to cover previously mined areas or temporarily stockpiled. The exposed overburden, the earth that is between the topsoil and the coal seam, is leveled, drilled, and blasted. Then the overburden material is removed down to the coal seam, usually by a dragline or a shovel and truck operation. The uncovered coal seam is then drilled and blasted. The raw coal is then transported to a temporary storage area where it may be crushed and screened then moved to a loading storage area.

What are the impacts with a large-scale coal strip mine?  Strip mining is inherently destructive to large areas, disturbing land and watersheds for many decades. During the mining process there are noise impacts from blasting, trucks, large equipment, and the construction and operation of coal transport systems.  Diesel emissions from mining equipment and coal transport equipment (truck, train, ship), will degrade air quality and may pose adverse health effects to nearby residents.  Large amounts of coal dust will be generated during the mining, transport and storage phases.  Run-off and waste water discharges from mine facilities will have impacts on fish bearing streams and waterways with potential changes in ph and increases in sedimentation.  Disturbed lands may expose minerals to chemical reactions resulting in heavy metals leaching, resulting in highly toxic water run-off.

Once mining is over, do the strip mines get reclaimed?  The 1977 Surface Mining Control and Reclamation Act and the State of Alaska’s implementation of it requires that mining sites be restored to their original contours. Mining companies have received waivers from this provision by showing that the leveled area will be developed for industrial or commercial purposes.  One example where reclamation has been ineffective is in Montana, where, according to the U.S. Department of the Interior’s Office of Surface Mining (OSM) in Montana, as of October 2005, over 62,000 acres have been permitted for strip mining.  Over 31,000 acres have been mined.  According to the Montana Department of Environmental Quality 2006 Annual Report, of the 31,000 acres to be mined only 216 acres have been released from their surety bonds because they had completed all four phases of land reclamation. 

Is there such a thing as ‘Clean Coal’?  Proponents of coal-derived liquids claim they are “clean” because the fuel is sulfur-free, but when coal is converted to liquid fuels, two streams of carbon dioxide (CO2) are produced: one at coal-to-liquids production plants and one from exhaust pipes of the vehicles that burn the fuel. Emissions from coal-to-liquids production plants are much higher than those from producing and refining crude oil to produce gasoline, diesel, and other transportation fuels.[1] If the CO2 from coal-to-liquids plants is captured instead of being released into the atmosphere, then CO2 emissions would be reduced some but would still be higher than emissions from today’s crude oil system. Even capturing 90 percent of the emissions from coal-to-liquid plants leaves emissions at levels somewhat higher than those from petroleum production and refining.[2]

Does coal contribute to climate change and if so, how does it compare to other traditional and alternative energy sources?  CO2 emissions account for approximately 80% of global warming potential.  According to EPA, annual carbon dioxide emissions from coal-fired power plants are greater than the emissions from all cars, trucks, planes, trains, and other forms of transportation combined. For electricity generation coal produces 83% of CO2 emissions.[3]  CO2 emissions are not regulated at the federal level. In 2004, power plant CO2 emissions were 27 percent higher than they were in 1990.[4]  The Energy Information Administration projects that the increase in coal generation will result in an additional 1.1 billion tons of annual CO2 emissions from the electric industry.[5] This represents a 43% increase in total electric industry CO2 emissions above 2004 levels.  Petroleum has about 25 % less carbon than coal.  Natural gas has about 45% less carbon than coal.  Air emissions associated with generating electricity from solar, wind, tidal, geothermal are negligible because no fuels are combusted in these processes.

Is coal a major source of mercury emissions in the U.S.?  According to EPA, Coal-burning power plants are the largest human-caused source of mercury emissions to the air in the United States, accounting for over 40 percent of all domestic human-caused mercury emissions.[6]  Approximately 75 tons of mercury are found in the coal delivered to U.S. power plants each year and about two thirds of this mercury is emitted to the air, resulting in about 50 tons being emitted annually.  Mercury is deposited to the earth’s surface through rain or snow, and then fish take in mercury through a process of bioaccumulation.   People and animals are mainly exposed to mercury when they eat fish that has been exposed to mercury.  The effects of mercury exposure can be severe.  Mercury can affect the nervous system; fetuses, infants, and children are the most sensitive to mercury exposure.

How will the cost of coal be affected by future legislation? U.S. Energy Information Administration says in a new analysis that the average delivered price of coal to power plants by 2020 would increase from $1.39 per million British thermal units (Btu) in the reference case to $2.06, an increase of 48 percent.  The increase would be more dramatic over the ensuing decade; by 2030, the delivered price of coal would increase from $1.51 per million Btu to $2.73.

What other pollutants are caused by coal? Electric utilities represent 25 percent of total national Nitrous Oxide emissions in 1998 of which coal combustion accounted for almost 90%.[7]  NO2 can irritate the lungs and lower resistance to respiratory infection (such as influenza); it contributes to pollutant haze, which impairs visibility and can reduce residential property values and revenues from tourism.  And NOx can cause severe adverse impacts on water quality and the aquatic environment that are critical for healthy estuarine ecosystems.  In 2004 electricity generation was responsible for 86% of the Sulfur Dioxide emissions in the U.S. with coal combustion accounting for 92% of those emissions[8]  SO2 is a major contributor to regional haze; Major health effects associated with high concentrations of SO2 include respiratory illness, cardiovascular disease, and mortality.  Together SO2 and NOx are the major precursors to acid rain that is associated with several environmental and human health effects.

What can be done to reduce SO2, and how effective are “scrubbers”

The primary means for coal-fired power plants to reduce SO2 emissions are through burning low-sulfur coal and/or installing post-combustion flue gas desulphurization equipment (FGDs or “scrubbers”). FGD systems can be categorized as “wet” or “dry.” Wet scrubbers, which combine water with limestone or lime to remove SO2 from the flue gas, are the most widely used. Dry scrubbers consist of a gas cooling system and reagent injection system that are used in conjunction with particulate control equipment to collect SO2 as a dry powder rather than a wet slurry.  In 2004 only 35 percent of the coal used to generate electricity was consumed in scrubbed units.[9]  The SO2 removal efficiencies of wet scrubbers range from 30 to 97 percent.  Dry scrubbers typically achieve SO2 removal efficiencies between 40 and 60 percent.[10] 

How effective is ‘carbon sequestration?’  Currently there are no commercially operating power plants that capture and sequester CO2 emissions in the U.S.  While Integrated Gasification Combined Cycle (IGCC) is the coal-fired power plant technology that provides the greatest potential for minimizing emissions associated with using coal to produce electricity, the technology is not currently commercially competitive due to the higher costs associated with building an IGCC plant.[11]  CO2 capture process adds complexity to the optimal design of desulphurization and other gas clean-up processes and increases both energy consumption and the amount of coal required to generate the same amount of electricity.[12]