Natural Gas

What is natural gas?
How is natural gas formed?
History of usage of natural gas.
How is natural gas extracted?
How do we use natural gas and why?
What are natural gas reserves?
Why should we be conservative in our use of natural gas?
What can be done to improve the way we use natural gas?
Sources

What is natural gas?

Natural gas is mostly made up of a gas called methane, a very potent greenhouse gas. Methane is a simple chemical compound that is made up of carbon and hydrogen atoms. Its chemical formula is CH4 – one atom of carbon along with four atoms hydrogen. Natural gas is lighter than air and highly flammable so that it burns almost completely.
There is no ash and very little air pollution.
It is colorless, shapeless, and in its pure form, odorless. Before it is sent to the pipelines and storage tanks, it is mixed with a chemical that gives a strong odor, almost like rotten eggs, so that it will be easy to smell if there’s a leak.

Energy Safety Note!

If you smell that rotten egg smell in your house, tell your folks and get out of the house quickly. Don’t turn on any lights or other electrical devices. A spark from a light switch can ignite the gas very easily. Go to a neighbor’s house and call for emergency help.
 

How is natural gas formed?

Carboniferous Forest

During the Carboniferous Period, between 360 to 286 million years ago, the land was covered with swamps filled with huge trees, ferns and other large leafy plants, similar to the picture to the left.
As the trees and plants died, they sank to the bottom of the swamps forming layers of a spongy material called peat. Over many hundreds of years the peat was covered by rock and sediment.

More and more rock piled on top of more rock, and it weighed more and more so that the peat was squeezed and squeezed until the water came out of it and eventually, over millions of years, it turned into coal. Methane and natural gas were also formed in this process.
At this time the seas and lakes abounded with organisms such as plankton. When these organisms died they settled on the bottom in large quantities. Over a long period of time, this organic matter, mixed with mud, got buried under heavy layers of sediment. The resulting high levels of heat and pressure caused the organic matter to chemically alter; first into a waxy material known as kerogen which is found in oil shales, and then with more heat into liquid petroleum and natural gas.

History of usage of natural gas:

Many early writers, described the natural petroleum seeps in the Middle East, especially in the Baku region of what is now Azerbaijan. The “eternal fires” of the fire-worshiping religion of the ancient Persians, in the area of present day Iraq, were reported in Plutarch’s writings around 100 to 125 A.D. These fires probably were from natural gas escaping from cracks in the ground and ignited by lightning.

For many years, it was discarded as worthless. Even today, some countries still get rid of it by burning it in giant flares, so large they can be seen from the Space Shuttle. Yet, it is one of the most valuable fuels we have.

In 1821 in Fredonia, New York, William A. Hart drilled a 27 foot deep well in an effort to get a larger flow of gas from a surface seepage of natural gas. This was the first well intentionally drilled to obtain natural gas.

Improvements in metals, welding techniques and pipe making during the War made pipeline construction more economically attractive. After World War II, the nation began building its pipeline network. Throughout the 1950s and 1960s, thousands of miles of pipeline were constructed throughout the United States. Today, the U.S. pipeline network, laid end-to-end, would stretch to the moon and back twice.

How is natural gas extracted?

Researchers have found that gas is not only found in pockets by itself but in many cases, with oil. Often, both oil and gas flow to the surface from the same underground formation.
Like oil production, some natural gas flows freely to wells because the natural pressure of the underground reservoir forces the gas through the reservoir rocks. These types of gas wells require only a “Christmas tree”, or a series of pipes and valves on the surface, to control the flow of gas.

However, in most cases some type of pumping system will be required to extract the gas present in the underground formation. One of the most common is the “horse head” pump which rocks up and down to lift a rod in and out of a well bore, bringing gas and oil to the surface.

Often, the flow of gas through a reservoir can be improved by creating tiny cracks in the rock, called “fractures,” that serve as open pathways for the gas to flow. In a technique called “hydraulic fracturing,” drillers force high pressure fluids (like water) into a formation to crack the rock. A “propping agent”, like sand or tiny glass beads, is added to the fluid to prop open the fractures when the pressure is decreased.
Because of the increased risk of earth quakes due to this ‘hydraulic fracturing’ there’s quite a bit of protest going on in certain European countries against the use of this technique.

Once natural gas is produced from underground rock formations, it is sent by pipelines to storage facilities, then by smaller pipes to homes and factories.

How do we use natural gas and why?

Natural gas provides one-fifth of all the energy used in the United States and around 24% of the world’s consumption of energy. Natural gas is, in many ways, the ideal fossil fuel. Two big advantages of natural gas are that it is easy to pipe from one location to another and that it burns very cleanly. It is also very convenient to use.

More and more, we are using gas in power plants to generate electricity. Factories are using more gas, both as a fuel and as an ingredient for a variety of chemicals.
Natural gas is especially important in homes, where it supplies nearly half of all the energy used for cooking, heating, and for fueling other types of home appliances.

What are natural gas reserves?

Natural gas reserves are years of production left in the ground with current proved reserves. Proved reserves are gas reserves that can be extracted in an economically profitable way. At present this is estimated at 61 years in the worst case scenarios, and up to 167 years with the most optimistic proved reserve estimates.

The huge gap in estimates comes from the fact that we don’t know exactly what our gas consumption will be in the future, only that our consumption is constantly increasing, and because we’re not sure whether all of the proved reserves can be recovered.

There is still some uncertainty about how much it will cost to get it out of the ground in the future. Like oil, there is “easy” gas that can be produced from underground formations, and there is gas that is not so easy. If we can find better and cheaper ways to find more of the “easy” gas and produce some of the more difficult gas, we can rely increasingly on natural gas in the future.

However, there are limits on how much natural gas we can find and get out of the ground, at some point in time, the production of each resource within an area, country, or globally will reach a maximum value, after which, the production will decline until it reaches a point where is no longer economically feasible or physically possible to produce.

Scientist are also continually looking for ways to obtain and use gas from new sources. They have discovered that natural gas can be found in a variety of different underground formations, including:
• shale formations
• sandstone beds
• coal seams
Some of these formations are more difficult and more expensive to produce than others, but they hold the potential for vastly increasing the world’s available gas supply.

Other sources of unconventional gas include “tight sand lenses”. These deposits are called “tight” because the holes that hold the gas in the sandstone are very small. It is hard for the gas to flow through these tiny spaces. To get the gas out, drillers must first crack the dense rock structure to create ribbon-thin passageways through which the gas can flow.

Coalbed methane gas that is found in all coal deposits was once regarded as only a safety hazard to miners but now, due to research, is viewed as a valuable potential source of gas.

Scientists are also studying another type of gas, called methane hydrateS, found in deep ocean beds or in cold areas of the world, such as the North Slope of Alaska or Siberia in Russia. A methane hydrate is a tiny cage of ice, inside of which are trapped molecules of natural gas.

Research is also continuing on a theory that gas pockets that were not formed from decaying matter but were formed during the creation of the Earth may be found deep in the ground.

If we manage to tap into these new resources, gas reserves will increase, however these new technologies may be more costly. It is likely that renewable energy supplies will then become more in demand as they may turn out to be cheaper than the exploitation of fossil fuel reserves. Alternative sources of energy include nuclear, hydroelectric, solar, wind and geothermal.

Why should we be conservative in our use of natural gas?

Natural gas is a very precious energy source because of all fossil fuels it is the one that burns the cleanest with virtually no pollution.

However, quite a bit of gas escapes during transportation through pipelines. Remember that natural gas consists mostly of methane. Methane turns out to be an extremely potent greenhouse gas; Twenty times more effective at trapping heat in the atmosphere than carbon dioxide. Many scientists believe methane escaping into the atmosphere is causing the earth’s temperature to rise, along with carbon dioxide, and this warming could be altering the earth’s climate.

What can be done to improve the way we use natural gas?

It is of utmost importance to make sure there are no leaks in the pipelines which transport gas from its source to storage tanks and our homes.

Sources:
http://en.wikipedia.org/wiki/Fossil_fuel 
http://www.energyquest.ca.gov/story/chapter08.html