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Underground Natural Gas Storage Basics

John Poullain, P.E.

Course Outline

This two-hour online course summarizes basic information and issues concerning the underground storage of natural gas (NG) and the history of storage development. The physical and operating characteristics and economics of underground storage are described including the advantages, limitations and problems of the traditional types of storage facilities. Description of the various methods and procedures are provided to give an understanding of typical problems encountered in underground gas storage developments. The regulatory function of the Federal Energy Regulatory Commission is described to provide an overview of NG distribution and the national storage capacities.

This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.

Learning Objective

At the conclusion of this course, the student will:

Intended Audience

This course is intended for civil engineers and environmentalists.

Benefit to Attendees

The student will gain an understanding of the traditional types of underground natural gas (NG) storage along with the advantages, limitations, physical characteristics and problems of each. The student will also learn methods used for measuring gas capacities that affect NG delivery. Also described are the history of underground storage and current developments for additional storage facilities. Safety considerations and potential hazards to protect from during operation as well as preventing NG migration or releases into underground formations and the environment are also discussed. NG storage facilities must be maintained to operate efficiently to prevent losses.

Course Introduction

This course provides basic information for the underground storage of NG. About 23% of energy consumed in the US is from NG. And about 50% of the total consumption are for the commercial and industrial sectors and about 20% are for residential sectors. NG is used as a raw material for products such as paints, fertilizer, plastics, dyes, photographic film, medicines and antifreeze. It is used to produce electricity, steel, paper, brick and glass among many others. Most of the NG used in the US is produced in the US and the remainder comes from Canada by pipeline and also from Liquefied Natural Gas (LNG) shipped by tankers. Necessary measures to maintain the storage facilities and equipment as well as any unsound conditions or potential problem areas are considered.

Underground storage of NG was developed in the early 1900's to offset volatility in NG prices caused from the varying demand and supply imbalances during the seasons of the year. Because the technology for the large pipelines necessary for distribution was not available at that time storage became a more feasible solution. Distributions of NG by mains and service pipelines were necessary to serve regionally scattered underground storage. Storage solved many regional needs in the US and helped to reduce the amount of pipelines required.

More recently it's been feasible to liquefy NG and ship the LNG on tankers at temperatures below 260 F to meet NG demands. LNG occupies 1/600 of volume NG when in its gaseous state. LNG can be stored in chilled tanks close to consumers and then changed back to NG and distributed by pipelines. It is a feasible alternative for those areas where gas deposits could not be supplied economically by pipelines. Another advantage of LNG usage over NG stems from the liquefaction process, which results in a product that is almost pure methane by removing the carbon dioxide, oxygen, sulfur and water. Methods are being used to convert and recycle waste and byproducts into usable energy. Landfill biogas digesters for instance convert wastes to NG, which is actually methane gas.

Many advances have been made in mechanical equipment such as remote leakage detectors, monitoring systems and alarms that safeguard against the threat of natural gas releases. Periodic inspections, knowing when a component of a system is defective or improperly maintained and understanding what is necessary to correct observed problems are important to continue proper operations of storage facilities.

Course Content

The course is based on the Federal Energy Regulatory Commission (FERC) staff report, "Current State of and Issues Concerning Underground Natural Gas Storage", (2004 publication, 19 pages), PDF file. The course is also based on the report, "Storage of Natural Gas", (2004 report, 5 pages).

The links to the course materials are:

Current State of and Issues Concerning Underground Natural Gas Storage

Storage of Natural Gas

You need to open or download above documents to study this course.

Please click on the above underlined hypertext to view, download or print the document for your study. Because of the large file size, we recommend that you first save the file to your computer by right clicking the mouse and choosing "Save Target As ...", and then open the file in Adobe Acrobat Reader. If you still experience any difficulty in downloading or opening this file, you may need to close some applications or reboot your computer to free up some memory.

Course Summary

This course serves as a guide for the traditional types of underground NG storage and the physical and operational characteristics, advantages, limitations and problems of each type. Current development in underground storage and the regulatory role of the FERC are described. Potential impacts on the underground environment during operation of the facilities are considered.

Related Links

For additional technical information related to this subject, please refer to:

Natural Gas Uses and Consumer Benefits
The Natural Gas Supply Association for education and information on NG regulations, environment, technology, storage and exploration maintains the site.
Onshore technical data and offshore pipeline oil and gas projects are discussed. The site also offers guidance on recovery systems and methods of exploration and distribution.


Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.