Method and system for selecting and using a salt cavern to store very pure hydrogen

A method for forming and maintaining a permeation barrier of a salt cavern, comprising:

• compressing a fluid to produce a compressed fluid;
• introducing the compressed fluid into a salt cavern to produce stored fluid within the salt cavern;
• forming a permeation barrier at least along a portion of walls of the salt cavern, wherein the porosity of the walls of the salt cavern is partially reduced to a size substantially small so as to prevent substantially all of the stored hydrogen from passing therethrough;
• and
• regulating the pressure of the salt cavern above a lower limit and below an upper limit to maintain the permeation barrier wherein the fluid is hydrogen having a purity of at least 95% or greater,
• wherein the improvement comprises the upper limit exceeding about 1 psi per liner foot of cavern depth,
• wherein the upper limit is at a pressure less than about 4 psi per linear foot of depth within the cavern, and
• wherein the improvement further comprises optimizing one or more factors selected from the group consisting of a salt cavern roof shape, a salt cavern aspect ratio, a creep constant of the salt at a location in which the salt cavern resides, a tensile strength of the salt at the location in which the salt cavern resides, a compressive strength of the salt at the location in which the salt cavern resides, a Young's modulus of the salt at the location in which the salt cavern resides, and combinations thereof, to thereby result in the upper limit.

A system for forming and maintaining a permeation barrier within a salt cavern, comprising:

• a compressor configured to pressurize hydrogen product within the salt cavern to form stored hydrogen wherein the compressed hydrogen product introduced into the salt cavern comprise a purity of at least 95% or greater;
• a flow network positioned between the compressor and the salt cavern, the flow network comprising a first leg, a second leg and a third leg;
• the first leg in flow communication with the salt cavern to introduce product hydrogen into the salt cavern to form stored hydrogen that is stored at a pressure above a lower limit and below an upper limit to form a permeation barrier;
• the second leg in flow communication with a hydrogen pipeline and the first leg to discharge the stored hydrogen formed from the salt cavern;
• and
• the third leg in flow communication with the salt cavern to introduce a fluid into the cavern to maintain the permeation barrier,
• wherein the improvement comprises the upper limit exceeding about 1 psi per liner foot of cavern depth,
• wherein the upper limit is at a pressure less than about 4 psi per linear foot of depth within the cavern, and
• wherein the improvement further comprises optimizing one or more factors selected from the group consisting of a salt cavern roof shape, a salt cavern aspect ratio, a creep constant of the salt at a location in which the salt cavern resides, a tensile strength of the salt at the location in which the salt cavern resides, a compressive strength of the salt at the location in which the salt cavern resides, a Young's modulus of the salt at the location in which the salt cavern resides, and combinations thereof, to thereby result in the upper limit.

A method for storing high purity hydrogen product in a salt cavern, comprising:

• removing the high purity hydrogen product from a high purity hydrogen pipeline;
• compressing the high purity hydrogen product to produce a compressed high purity hydrogen product;
• introducing the compressed high purity hydrogen product comprising a purity of about 99% or greater into the salt cavern to produce stored high purity hydrogen within the salt cavern;
• thereby
• pressurizing at least a portion of the walls of the salt cavern walls characterized by a halite structure having a minimum purity of at least about 75% of sodium chloride, to substantially confine the stored high purity hydrogen within the salt cavern at a pressure, and measuring and adjusting the pressure to maintain the pressure between a predetermined lower limit and a predetermined upper limit,
• wherein the improvement comprises the predetermined upper limit exceeding about 1 psi per linear foot of depth of the cavern
• wherein the upper limit is at a pressure less than about 4 psi per linear foot of depth within the cavern, and
• wherein the improvement further comprises optimizing one or more factors selected from the group consisting of a salt cavern roof shape, a salt cavern aspect ratio, a creep constant of the salt at a location in which the salt cavern resides, a tensile strength of the salt at the location in which the salt cavern resides, a compressive strength of the salt at the location in which the salt cavern resides, a Young's modulus of the salt at the location in which the salt cavern resides, and combinations thereof, to thereby result in the upper limit.