Multimedia Gallery. Park Passes. Technical Announcements. Employees in the News. Emergency Management. Survey Manual. The four ranks are:. The precursor to coal is peat. Peat is a soft, organic material consisting of partly decayed plant and mineral matter. When peat is placed under high pressure and heat, it undergoes physical and chemical changes coalification to become coal.
The U. In , coal-fired power plants provided This is anthracite, the highest rank of coal. It is a hard, brittle, and black lustrous coal, often referred to as hard coal, containing a high percentage of fixed carbon and a low percentage of volatile matter.
Anthracite is not as commonly mined as other ranks of coal. It played a significant role in Pennsylvania coal during the Industrial Revolution in the United. This sample is of bituminous coal, a middle rank coal between subbituminous and anthracite formed by additional pressure and heat on lignite. Usually has a high Btu value and may be referred to as "soft coal.
Cannel coal is a type of bituminous coal that is also sometimes referred to as a type of oil shale. It's name likely came from the word " candle. Read more about our coal research here:.
Clinker coal is the result of a seam of coal catching fire and burning so hot that it baked surrounding rock layers into brick-like formations. Read more about our. This sample is of peacock coal. Peacock coal is not a specific class of coal, but rather the name for an effect in which oxidizing materials in the coal create a dazzling array of colors on the surface of the coal.
The ranking depends on the types and amounts of carbon the coal contains and on the amount of heat energy the coal can produce. The rank of a coal deposit is determined by the amount of pressure and heat that acted on the plants over time. All of the anthracite mines in the United States are in northeastern Pennsylvania.
In the United States, anthracite is mainly used by the metals industry. Bituminous coal in the United States is between million and million years old. Bituminous coal is used to generate electricity and is an important fuel and raw material for making coking coal or use in the iron and steel industry. Most subbituminous coal in the United States is at least million years old. The remainder was produced in Alaska, Colorado, and New Mexico. Lignite coal deposits tend to be relatively young and were not subjected to extreme heat or pressure.
Lignite is crumbly and has high moisture content, which contributes to its low heating value. Lignite is mostly used to generate electricity. A facility in North Dakota also converts lignite to synthetic natural gas that is sent in natural gas pipelines to consumers in the eastern United States. Coal explained. What is energy? Units and calculators. Use of energy. Energy and the environment. Also in What is energy? Forms of energy Sources of energy Laws of energy.
Also in Units and calculators explained Units and calculators Energy conversion calculators British thermal units Btu Degree days. If demands significantly exceed a power plant's capacity to generate energy this may cause temporary blackouts. Historically, fossil fuels were available in plentiful supply that was easy to obtain and transport. But now signals are given that the supply is running out and that it will take centuries to be replenished.
Both sources and sinks of fossil fuels are limiting in their use. Sources are deep earth layers and sinks are for example air and water, which absorb fossil fuel waste products. Burning fossil fuels is responsible for environmental issues that are high on the political agenda these days.
Examples are greenhouse gas accumulation, acidification, air pollution, water pollution, damage to land surface and ground-level ozone. These environmental problems are caused by release of pollutants that are naturally present in fossil fuel structures, such as sulphur and nitrogen. Natural gas does not release as much carbon dioxide because of its methane structure.
The largest emissions are cause by coal combustion. Coal may result in underground fires that are virtually impossible to extinguish. Coal dust can even explode. This makes coal mining a very dangerous profession.
Oil may end up in soil or water in raw form, for example during oil spills or wars. This has caused many natural disasters in the past. Why than are we still using fossil fuels to such a large extend? The answer is simple; because this is cheaper than any type of reasonable alternative we now know.
Some environmental scientists predict that fossil fuel prices will increase in the coming century because of scarcity. This may cause an eventual transfer to renewable energy sources. According to Bjorn Lomborg , this will eventually happen. The IPCC is not sure whether a fossil fuel future can be entirely ruled out. McKinney, M. Miller, G. Climate change glossary. The greenhouse effect mechanism. Emissions and infrared absorption by greenhouse gases. Overview of emission reductions for each country according to Kyoto.
Possible policy measures to achieve Kyoto targets. Trading emission permits to achieve Kyoto targets. Discussions of the greenhouse effect. History of global warming.
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