|Fig. 1: Types of underground caverns. (Courtesy of the DOE)|
The ability of a system to perform work-energy. Energy is an ever-present component of one's daily life. It takes form in several different ways, such as; sound, fire, movement and many more. Our goal is to maximize the amount of energy we have at our disposal to accomplish tasks like heating our homes and fueling our cars. Not only does energy have an important role in that of which previously mentioned, but it also keeps our bodies alive and well. The reason we eat, drink, and sleep is to refuel our bodies because they are low on energy. Being that energy is needed in everything we do; it benefits us to have it readily available - giving us the option to use it at our leisure. Due to its many forms, there are a number of ways to store energy, each having its own benefits and drawbacks. A few types of energy storage will be depicted below.
Taking advantage of the energy stored within atoms, a nuclear bomb uses either nuclear fission or fusion to release the energy that holds the atom together. Nuclear fission is denoted as the splitting of the nucleus of an atom into two smaller fragments by a neutron.  Nuclear fusion is the combination of two smaller atoms. The combination or splitting of atoms release energy which is why the bombs produce a large impact when these actions are enacted. One of the more well-known atomic bombs, The Hiroshima Bomb, used nuclear fission.  The material used to craft this bomb was extremely radioactive - more susceptible to long chain reactions of nuclear fission. The bomb released 5 × 1013 J. 
Natural gas is usually held in 3 types of underground facilities; depleted gas reservoirs, aquifers and salt cavern formations. See Fig. 1 for an illustration of these storage facilities. The most important attributes of a natural gas storage facility are its capacity to hold natural gas for the future and its deliverability rate or the rate at which the gas can be withdrawn.  The most readily available natural gas storage sites in the United States are depleted oil fields - which also makes them the most commonly used. Aquifers are the most expensive form of storage.  Salt caverns are the best facility in both areas of discernable characteristics in terms of deliverability rate and the capacity to hold natural gas. Their walls are very strong which help them resist reservoir degradation.  By 2015 there were 415 total natural gas facilities with a total storage capacity of 3453 billion cubic feet.  1 cubic foot of natural gas is equivalent to 1000 Btu. 1 Btu equates to 1055 J. So, 3453 billion cubic feet releases 3.64 × 1018 J.
|Fig. 2: Turbine diagram (Source: Wikimedia Commons).|
Dams are one of the most used approaches in storing and creating energy. The combination of water and gravity has a lot of potential, so having a plethora of water accessible means you have access to a large amount of energy as well.  When water from a dam passes through, the turbines spin creating electricity.  See Fig. 2 for an illustration of a turbine. The more water you have behind a dam, the more electricity you'll get from the water passing through. The Grand Coulee Dam is one of the largest in the world - standing at 550 feet high and 5,223 feet long.  At its peak it is capable of spilling 1 million cubic feet of water per second. The corresponding power is 550 ft × .3048 m/ft × 106 ft3/sec × 28.32 kg/ft3 × 9.8 m/s2 = 4.65 × 1010 J/s, or 46.5 gigawatts.
As previously mentioned, energy takes shape in many different forms. This necessitates a large amount of storage devices to efficiently accommodate all forms. The plethora of energy storage devices goes far beyond just that of which I have mentioned in this paper. Energy storage is a key concern for a reason and the more ways to store energy made available to us, the more readily available it is for our consumption.
© Bryce Marion. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
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