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Electricity Education - Natural Gas
Formation of Natural Gas
Natural gas is tiny bubbles of odorless gas. This odorless gas is a mixture of light hydrocarbons that include methane, ethane, propane, butane, pentane, carbon dioxide, helium, hydrogen sulfide and nitrogen. If formed millions of years ago as sea plants and animals died and became buried on the bottom of the ocean floor. As the years passed, the remains of these dead plants and animals were placed under enormous amounts of heat and pressure caused by the continual addition of sediment deposits. This organic material became coal, crude oil and natural gas.
The oil and gas are then squeezed out of the shale where they were initially deposited and begin to rise through porous sedimentary rocks. These sedimentary rocks include sandstone and limestone. Because natural gas and oil are less dense than water, migration continues until these hydrocarbons reach a layer of impermeable rock. Many times vast amounts of natural gas and oil are collected beneath domes formed by folded sedimentary rocks. A majority of these domes are located along the Gulf of Mexico; therefore, it is no surprise that Texas and Louisiana account for close to 60% of all the natural gas production yearly. The largest reserves are in the former Soviet Union and throughout the Middle East.
Exploration of Natural Gas
Natural Gas was first discovered because of flames shooting up from the earth's surface. Upon further study, it was found that the natural gas escaped through small gaps in the rocks into the air and if there was enough activation energy a fire would burn.
Today, geologists and engineers use seismic surveys to study the underlying rocks. The seismic surveys aid in determining where to drill wells into reservoir rocks for extraction of the gas.
Uses of Natural Gas
Natural gas is used for numerous activities in our society. These uses include industrial, residential, commercial, electrical power generation, propane fuel and vehicle fuel. Heating and the generation of electricity are the main uses of natural gas, using about 90% of the resource. Approximately 23% of all the energy consumption in the United States is from the use of natural gas.
More then 62 million households use it to fuel stoves, furnaces, water heaters and many other appliances around the house. In industry, natural gas is burned to produce heat, which boils water that creates steam to pass through giant turbines. A turbine is used to generate electricity at about a 50% efficiency rate. The downfall to using natural gas is that it is generally more expensive than other forms of fuel.
Because natural gas is a clean burning fuel it is excellent for co-generation. Co-generation plants capture the excess heat let off during the burning of natural gas and sell the heat to local industries for processing or heating.
See a Macromedia Flash Animation of how a Natural Gas Power Plant Works
How do we get it?
Once the gas is found, it flows up through the ground to the surface and into large pipelines for domestic transport. Most of the time natural gas is under tremendous pressure, thus exiting the hole on its own. Sometimes, however, pumps are used for the collection of natural gas from beneath the surface. It is then transported by pipeline in its natural state or liquefied and transported by ship or rail.
Natural gas is measured in British Thermal Units (Btu) and cubic feet. A Btu is a measurement of energy. It is the amount of energy needed to raise the temperature of 1 pound of water 1 degree Fahrenheit at a temperature of 39.2 degrees Fahrenheit. One cubic foot of natural gas is equal to 1031 Btu. The United States currently produces 18,964 billion cubic feet of natural gas yearly, but it consumes 23,018 billion cubic feet.
The Future of Natural Gas
Natural gas is the cleanest burning fossil fuel, produces very few pollutants and has fewer emissions than coal and oil. There will be an increase in the use of natural gas in the very near future in order to combat acid rain, global warming and the deterioration of the ozone layer.
Fuel cells appear to be an environmentally friendly use of natural gas. Fuel cells are used to generate electricity, operating very much like a battery.