Question

Coal has played a vital role in the civilization of man-kind. Please tell me everything you can about coal. Where do we find it? How is it made? What are its advantages? Disadvantages? And lastly, tell me everything about our use of coal and its impact on the environment.

Answer 1

Coal

Where do we find it?

In geologic terms, coal is a sedimentary rock containing a mixture of constituents, mostly of vegetal origin. Vegetal matter is composed mainly of carbon, hydrogen, oxygen, nitrogen, sulfur, and some inorganic mineral elements. When this material decays under water, in the absence of oxygen, the carbon content increases. The initial product of this decomposition process is known as peat. Peat can be formed in bogs, marshes, or freshwater swamps, and in fact huge freshwater swamps of the geologic past provided favourable conditions for the formation of thick peat deposits that over time became coal deposits. The transformation of peat to lignite is the result of pressure exerted by sedimentary materials that accumulate over the peat deposits. Even greater pressures and heat from movements of Earth’s crust (as occurs during mountain building), and occasionally from igneous intrusion, cause the transformation of lignite to bituminous and anthracite coal.

How is it made?

Coal is formed when dead plant matter submerged in swamp environments is subjected to the geological forces of heat and pressure over hundreds of millions of years. Over time, the plant matter transforms from moist, low-carbon peat, to coal, an energy- and carbon-dense black or brownish-black sedimentary rock.

Coal itself has a wide variation in properties, and can be categorized into four main types, or ranks—lignite, sub-bituminous, bituminous, and anthracite—in order of increasing carbon and energy content. Most of the coal burned in US power plants is bituminous or subbituminous coal.

A fifth type, called metallurgical (or “coking”) coal, is used for steelmaking.

All types of coal also contain sulfur, which, when burned, releases toxic air pollution. Sulfur content is determined by the conditions under which the coal is formed. Low-sulfur coal deposits develop in freshwater environments; high-sulfur deposits come from brackish swamps or marine-influenced environments [1].

In the United States, the sulfur content of coal varies along geographic lines, with most—though not all— eastern coal containing high levels of sulfur, and western coal containing much less.

Advantages of Coal

1. It is available in an abundant supply.
Industrialized countries, including the United States, India, China, and Russia, have a large amount of coal that is available to them. Some estimates have the US holding enough coal that has already been mined to fuel current resources for the next 400 years. That means we have access to this fuel in abundance, allowing societies to focus on other infrastructure needs.

2. It has a high load factor.
Using coal as a fuel provides a society with the potential for continuous power. Many infrastructures are specifically designed to use coal, offering a good utilization rate for this fossil fuel. It also provides a high load factor, giving us access to an efficient and predictable level of energy through combustion. That’s predictability isn’t something that other fuel resources can currently provide with current technologies.

3. Coal offers a rather low capital investment.
Many of our fuel and power generation technologies are already designed to use coal. This limits the amount of a capital investment which is required to create a new societal resource, especially when compared to nuclear or renewable energy resources.

4. Carbon capture and storage technologies can reduce potential emissions.
Safe capture and storage of carbon dioxide, referred to as CCS, is a technology that would capture and store the carbon dioxide that is produced by combusting this fossil fuel. Scrubbers and filters can also capture the CO2 before it is able to get into the atmosphere. This limits the amount of potential global warming that would be triggered by an increase in coal use.

5. It can be converted into different formats.
Coal can be converted into a gaseous state or into a liquid and still be used as if it were refined or raw. The conversion to a liquid or a gas creates a fuel that burns cleaner as well, which limits the production of ash and other byproducts that are created by the combustion process.

6. Coal can be used with renewables to reduce emissions.
Biomass technologies can be incorporated into existing coal facilities, allowing for a dual fuel source in the same power plant. This allows for coal to be used, but in lesser amounts, and that can help to reduce the amount of carbon dioxide and ash that gets produced from the burning process. This allows coal, which is a mature industry, to maintain its economic impact without fully compromising it while environmental protections can also be implemented.

7. It is a full-time energy resource.
Unlike solar or win, you can burn coal 24/7 to produce energy. This means it is a reliable power source that offers predictability for a modern society. There is no need to counter intermittence as there is with other power technologies that are being developed right now.

8. The global reserves for coal are estimated to be quite large.
The current global reserve for coal is estimated to be about 1 trillion tons. This means we have another 200 years of coal usage at current consumption levels above and beyond what our current stockpiles can currently provide. It is a potential energy resource that can help to develop the developing world, potentially improving the livelihoods of some of the world’s poorest populations.

Here Are the Disadvantages of Coal

1. It is not a renewable resource.
At some point, if we are continuously using coal for our power and energy needs, it will eventually become depleted. As a fossil fuel, there is a finite supply. We may have centuries of stockpiles available in some regions, but at some point, there must be a backup plan in place that can be implemented.

2. Coal contains a high level of carbon dioxide per British Thermal Unit.
Scientists believe that one of the greatest contributors to global warming is carbon dioxide that is manually produced. When comparing all forms of energy and power production that we use today, coal contains the most carbon dioxide for every BTU that is produced. According to the EIA, coal with a carbon content of 78% and a heating value of 14,000 BTU would produce about 204.3 pounds of CO2 per 1 million BTU.

3. Coal power can create high levels of radiation.
A byproduct of burning coal for power, called “coal ash,” produces radiation. This ash then settles around the surrounding areas of the coal plant. According to Scientific American, a coal power plant can produce up to 100 times more radiation than a nuclear power plant. Coal combustion can also produce mercury, nitrous oxide, heavy metals, and other potential environmental dangers.

4. Coal emissions are linked to health concerns.
People who are exposed to coal and its emissions have an increased risk of experiencing asthma and other air passageway inflammation conditions. Breathing in coal dust or ash is also known to be a cause for lung cancer development over time. A coal mining disease called “Black Lung” can impact total lung capacity, is incurable, and is often fatal. People with Black Lung literally die of suffocation.

5. Even clean coal still has high levels of methane.
Even with the best CCS technologies in place, clean coal still produces carbon dioxide and other environmental contaminants. CCS technologies do not address methane either. Although methane dissipates in the atmosphere rather quickly, it can sink to the bottom of the sea and impact our oceans and marine life for an indeterminate period of time.

6. Coal mines cause relocation and destruction.
Many coal mines use an open-cast method, which causes local animal habitats to be destroyed. Green spaces, waterways, and other spaces are impacted by coal pollution, which can eliminate fields and forests with fast devastation. Fires connected to coal mining create underground burning that can be difficult to remove. Established communities sometimes need to move to avoid the pollution of the coal mines as well, displacing people from their homes.

Use of Coal

Coal is primarily used as fuel to generate electric power in the United States. The coal is burned and the heat given off is used to convert water into steam, which drives a turbine. In 2012, about 39 percent of all electricity in the United States was generated by coal-fired power plants, according to the U.S. Energy Information Administration.

Certain types of coal can also be used for metallurgical processes, like forging steel, smelting metals, or even in smelting sands, which are used to cast metal. Finally, coal can be burned to provide heat for individual homes.

Impact of coal on the Environment

Coal impacts: global warming

Climate change is coal’s most serious, long-term, global impact. Chemically, coal is mostly carbon, which, when burned, reacts with oxygen in the air to produce carbon dioxide, a heat-trapping gas. When released into the atmosphere, carbon dioxide works like a blanket, warming the earth above normal limits.

Consequences of global warming include drought, sea level rise, flooding, extreme weather, and species loss. The severity of those impacts is tied directly to the amount of carbon dioxide we release, including from coal plants. In the United States, coal accounts for roughly one-quarter of all energy-related carbon emissions.

• Acid mine drainage (AMD) refers to the outflow of acidic water from coal mines or metal mines, often abandoned mines where ore- or coal mining activities have exposed rocks containing the sulphur-bearing mineral pyrite. Pyrite reacts with air and water to form sulphuric acid and dissolved iron, and as water washes through mines, this compound forms a dilute acid, which can wash into nearby rivers and streams.

• Air pollution from coal-fired power plants includes sulfur dioxide, nitrogen oxides, particulate matter (PM), and heavy metals, leading to smog, acid rain, toxins in the environment, and numerous respiratory, cardiovascular, and cerebrovascular effects.

• Air pollution from coal mines is mainly due to emissions of particulate matter and gases including methane (CH4), sulfur dioxide (SO2), and nitrogen oxides (NOx), as well as carbon monoxide (CO).

• Climate impacts of coal plants - Coal-fired power plants are responsible for one-third of America’s carbon dioxide (CO2) emissions, making coal a huge contributor to global warming.Black carbon resulting from incomplete combustion is an additional contributor to climate change.

• Coal dust stirred up during the mining process, as well as released during coal transport, which can cause severe and potentially deadly respiratory problems.

• Coal fires occur in both abandoned coal mines and coal waste piles. Internationally, thousands of underground coal fires are burning now. Global coal fire emissions are estimated to include 40 tons of mercury going into the atmosphere annually, and three percent of the world's annual carbon dioxide emissions.

• Coal combustion waste is the nation's second largest waste stream after municipal solid waste. It is disposed of in landfills or "surface impoundments," which are lined with compacted clay soil, a plastic sheet, or both. As rain filters through the toxic ash pits year after year, the toxic metals are leached out into the local environment.

• Coal sludge, also known as slurry, is the liquid coal waste generated by washing coal. It is typically disposed of at impoundments located near coal mines, but in some cases it is directly injected into abandoned underground mines. Since coal sludge contains toxins, leaks or spills can endanger underground and surface waters.

• Floods such as the Buffalo Creek Flood caused by mountaintop removal mining and failures of coal mine impoundments.

• Forest destruction caused by mountaintop removal mining - According to a 2010 study, mountaintop removal mining has destroyed 6.8% of Appalachia's forests.

• Greenhouse gas emissions caused by surface mining - According to a 2010 study, mountaintop removal mining releases large amounts of carbon through clearcutting and burning of trees and through releases of carbon in soil brought to the surface by mining operations. These greenhouse gas emissions amount to at least 7% of conventional power plant emissions.

• Loss or degradation of groundwater - Since coal seams are often serve as underground aquifers, removal of coal beds may result in drastic changes in hydrology after mining has been completed.

• Radical disturbance of 8.4 million acres of farmland, rangeland, and forests, most of which has not been reclaimed -- See The footprint of coal

• Heavy metals and coal - Coal contains many heavy metals, as it is created through compressed organic matter containing virtually every element in the periodic table - mainly carbon, but also heavy metals. The heavy metal content of coal varies by coal seam and geographic region. Small amounts of heavy metals can be necessary for health, but too much may cause acute or chronic toxicity (poisoning). Many of the heavy metals released in the mining and burning of coal are environmentally and biologically toxic elements, such as lead, mercury, nickel, tin, cadmium, antimony, and arsenic, as well as radio isotopes of thorium and strontium.

• Mercury and coal - Emissions from coal-fired power plants are the largest source of mercury in the United States, accounting for about 41 percent (48 tons in 1999) of industrial releases.

• Methane released by coal mining accounts for about 10 percent of US releases of methane (CH₄), a potent global warming gas.

• Mountaintop removal mining and other forms of surface mining can lead to the drastic alteration of landscapes, destruction of habitat, damages to water supplies, and air pollution. Not all of these effects can be adequately addressed through coal mine reclamation.

• Particulates and coal - Particulate matter (PM) includes the tiny particles of fly ash and dust that are expelled from coal-burning power plants. Studies have shown that exposure to particulate matter is related to an increase of respiratory and cardiac mortality.

• Radioactivity and coal - Coal contains minor amounts of the radioactive elements, uranium and thorium. When coal is burned, the fly ash contains uranium and thorium "at up to 10 times their original levels."

• Subsidence - Land subsidence may occur after any type of underground mining, but it is particularly common in the case of longwall mining.

• Sulfur dioxide and coal - Coal-fired power plants are the largest human-caused source of sulfur dioxide, a pollutant gas that contributes to the production of acid rain and causes significant health problems. Coal naturally contains sulfur, and when coal is burned, the sulfur combines with oxygen to form sulfur oxides.

• Thermal pollution from coal plants is the degradation of water quality by power plants and industrial manufacturers - when water used as a coolant is returned to the natural environment at a higher temperature, the change in temperature impacts organisms by decreasing oxygen supply, and affecting ecosystem composition.

• Toxins - According to a July 2011 NRDC report, "How Power Plants Contaminate Our Air and States" electricity generation in the U.S. releases 381,740,601 lbs. of toxic air pollution annually, or 49% of total national emissions, based on data from the EPA’s Toxic Release Inventory (2009 data, accessed June 2011). Power plants are the leading sources of toxic air pollution in all but four of the top 20 states by electric sector emissions.

• Transportation - Coal is often transported via trucks, railroads, and large cargo ships, which release air pollution such as soot and can lead to disasters that ruin the environment, such as the Shen Neng 1 coal carrier collision with the Great Barrier Reef, Australia that occurred in April 2010.

• Waste coal, also known as "culm," "gob," or "boney," is made up of unused coal mixed with soil and rock from previous mining operations. Runoff from waste coal sites can pollute local water supplies.

• Water consumption from coal plants - Power generation has been estimated to be second only to agriculture in being the largest domestic user of water.

• Water pollution from coal includes the negative health and environmental effects from the mining, processing, burning, and waste storage of coal.