How Natural Gas is Stored?

Close up of natural gas storage unit
Whether turning on a gas stove or heating our homes in the winter, we are able to use natural gas whenever we need it. To ensure its ready accessibility, natural gas is stored for future use through a few different methods. Here’s a look at the differences between those methods:

Understanding underground architecture

The natural gas we use to heat our homes and businesses generally comes from deep under the Earth’s surface. These underground pools of natural gas are actually pockets of decomposed organic matter like prehistoric plants or animals. Over time, the gas that comes from decomposing matter gets trapped by a resistant surface of non-porous rock in massive underground pools called plays.

Shale Play is the industry term for vast underground reservoirs of natural gas, as in the Marcellus Play.
When drilling for natural gas, there are a number of additional compounds that surface. For instance, the oil that comes from decomposition often tags along with methane in those deep shale plays, just as additional gases and water do. Since the methane we burn for heating and cooking needs to be pure, the gases that surface at the wellhead (where the drill is) require processing. It’s for this reason that natural gas in those plays has to be fully extracted before it can be reinserted for storage.


Underground storage options

Much of the natural gas we consume is stored similarly to the way we extract it—underground. Why underground? For one thing, subterranean storage is less likely to be tampered with. But, along with safety, natural gas can be stored at much higher pressures underground since the weight of the soil helps to keep things stable. In fact, that higher pressure also helps the natural gas travel through the pipelines when it’s time to extract it. There are five different methods for storing natural gas underground:

  • Salt caverns
  • Mines
  • Aquifers
  • Depleted reservoirs
  • Hard-rock caverns

Each of these storage methods has the ability to trap gases through some type of non-porous cap stone. With aquifers and salt caverns, injected gas shares the space with water or salt, respectively. In the case of shale plays, however, the only thing that was in the reservoir was gas, which is why a freshly-depleted reservoir is the most common kind of natural gas storage method. No matter which type of storage method is used, caverns need to be prepared to receive the natural gas. This often includes adding pipes and valves, as well as sealing any cracks that might have occurred with the original drilling. These costs, gas accessibility, ease of gas extraction, or proximity to a hub all go into the evaluation for a reservoir or cavern’s viability as a natural gas storage option.

Above-ground storage options

Sometimes a region simply doesn’t have available underground caverns. In this case, natural gas is stored in fabricated tanks above ground. These tanks allow for easy access and complete control of extraction. However, while the costs for above-ground storage options are typically less than underground, tanks can store only a fraction of the natural gas that underground caverns can. Another style of above-ground storage is the transportable tank. These are most often used to maximize the amount of Liquid Natural Gas (LNG) being moved. Transportable tanks can be loaded onto train cars, used with 18 wheelers, or moved onto barges for an overseas journey.

Keeping tabs on available gas

The amount of stored natural gas we have is constantly being monitored. The US Energy Information Administration has a weekly report on our nation’s reserves. Since natural gas is such an integral part of our daily lives, the availability of this resource is critically important. These numbers often influence business, even on an international level. And, as winter draws near, these reports can influence what you could be paying to heat your home. Whether it’s stored above ground, on the back of a semi, or deep beneath the Earth’s crust, the natural gas we pull from the Earth is still one of the most valuable resources we have. As renewable energy options become more advanced and the world’s top scientists look for an energy solution that does not consume our natural resources, the plentiful natural gas beneath American soil keeps our country moving—literally, in the case of Compressed Natural Gas (CNG), and figuratively through gas-powered electricity generation. Learn more about how you can better manage and use natural gas for your own home or business at IGS Energy, and see what other ways we help to bring the power of tomorrow to you.