coal and gas hydrate
Coal and Gas Hydrate Resources
adapted to HTML from lecture notes of Prof. Stephen A. Nelson Tulane University
- Provides 25% of world energy
- The world has 1 trillion tons of reserve
- U.S. has about 300 billion tons
- If all energy was to be supplied by coal, U.S. would have enough for at least 200 years
- Australia also has hundreds of years of resrerves
- Dominantly from plants buried in swamp environment
- On burial the coal changes character in the following stages:
- bituminous - The coal most of us are used to seeing. Black, "dirty" coal.
- anthracite - Hard, shiny black rock. Does not easily rub off onto your fingers.
- The steps in the transformation from buried plant debris to coal.
Formation of Coal
The character of coal changes as pressure and temperature increases. We notice a general trend towards higher carbon content as volatiles and moisture are lost. In the crust, at higher temperatures and pressures, metamorphism turns coal into graphite.
- Sulfur as sulfide oxides to form sulfuric acid in mines or on burning causes acid rain.
- Strip mining while cheapest, needs reclamation.
- Underground mining- subsidence.
- Ash left is 5- 20% of original volume.
- Transporting coal is difficult.
- Trains - Primary method of transportation.
- Conversion to electricity on site - The problem with this method is that you then need to transfer the power to remote locations that can use it. Transporting electricity loses a great deal of energy.
- Coal slurry in pipelines - Mixing coal with water to produce a semi-liquid material that can be piped. This is not done very much.
- Conversion to synthetic oil or gas - used to be done quite often to produce gas, before actual natural gas sources were utilized. One problem with this method is that the natural gas produced by this method happens to contain quite a lot of carbon monoxide mixed in with the methane.
Coal itself can be found near the surface and deep below ground. Due to this there are several different ways in which it is mined, depending on the location. Surface, or Strip Mining
- As the name implies, this
form of mining simply takes coal from near the surface. First, the
and soil overlying the coal must be removed. Then any rocks or
must be removed, generally by blasting with explosives and by using
land moving equipment. This waste rock is then set aside in spoil piles
while the coal underneath is mined, and is replaced after the mining
is completed. This method of mining generally recovers almost 100% of
coal present in the deposit.
- There are two major forms
of mines that are created using this method of mining. The first is a
- Surface spoils from haphazard coal mining pose severe acid drainage and contamination problems.
Lighter areas are mined.
- This method of mining recovers only fraction of the available coal.
- Sinkholes and troughs can be caused by this form of coal mining after the mines have been abandoned and the overburden collapses into the tunnels..
- The Department of Energy's news page about fossil fuels. This web page covers current headlines and activities regarding fossil fuels and associated power sources.
- The U.S.G.S. provides a good page on fossil energy resources. They cover coal, oil, gas, and their usages, availability, and environmental impacts.