INTERVIEW: Hydrogen storage knowledge gap must be closed to move past R&D rut

Hydrogen storage is necessary to enable the growth of a hydrogen industry, but research and development in this space is underdeveloped and knowledge gaps must be closed to move forward, Shadi Salahshoor, program manager at GTI Energy's new collaborative Sustain H2 project, said in an interview.

US-based Sustain H2 was launched by GTI Energy on Sept. 10, a hydrogen storage research collaboration with the International Energy Agency that argues the hydrogen value chain's success hinges on reliable large-scale storage.

"Eventually, once hydrogen becomes an energy commodity, we need to have the storage in place in case of any supply chain disruption and supply fluctuation, similar to what we see with the natural gas network," Salahshoor said.

However, several questions remain in this field, including where it would be best to store the molecule. Hydrogen is currently only being stored in salt caverns, including three projects in the Gulf Coast region, one currently under development in Utah and several others in the planning stage, Salahshoor said.

One developing project that aims to leverage salt caverns for hydrogen storage is Hy Stor Energy's Mississippi Clean Hydrogen Hub. The storage will provide a buffer for the intermittent renewable and wind solar energy being used to power the project's clean hydrogen, Hy Stor's chief commercial officer Claire Behar said in April this year.

Despite initial investments in US hydrogen storage looking at salt caverns, they are limited by region, Salahshoor said, with most being found in the Gulf Coast and Midwest areas.

Additionally, for larger-scale storage, salt deposits with enough thickness, called "salt domes," are more ideal, she said. These formations are even more limited than regular salt caverns; "domal" salt is almost entirely found in the Gulf Coast, according to the National Energy Technology Library.

Other potential geologies outside of salt storage include sedimentary basin storage, or aquifer storage. This method is well established in natural gas and CO2, Salahshoor said.

Depleted gas fields previously used for production are also potential candidates for reutilization as hydrogen storage, she said. Both these depleted fields and aquifer storage are much more available across the country than salt caverns, NETL data shows.

"The good thing is, we have experience with underground gas storage, so it's going to be a similar network, and just utilizing what we have, the geologists we have available for storing gaseous hydrogen and then reutilizing it when needed," Salahshoor said.

Depleted oil and gas fields are also being eyed for potential carbon storage for many of the same reasons as hydrogen. These depleted fields provide a space where project developers are already familiar with the geology and available infrastructure, Tim Dixon, general manager of the IEA Greenhouse Gas R&D Program, said in a Sept. 24 University of Texas Energy Symposium webinar.

However, Dixon raised concerns about the compatibility of these wells with CO2 storage, also saying that regulations would need to change to permit demonstrations of this storage method. He also said the overall storage capacity of these sites may not be large enough to meet the scale needed.

Tapping into existing infrastructure has its conveniences, but this comes with its own barriers. Salahshoor indicated the need for specialized workers on these projects who are familiar with repurposing gas infrastructure for hydrogen. Environmental considerations are necessary too, she said.

Despite these options under consideration, there are no commercial-scale or demonstrative versions of these technologies yet, Salahshoor said.

Getting past this research and development phase will require regulatory framework for permitting, developing and operating these storage spaces for hydrogen, she said.

Salahshoor pointed to the developing US Clean Electricity Investment Tax Credit, or US tax code 48E, as a potential policy that could provide guidance for energy storage development.

"Depending how those guidance and clarifications are being developed, that could impact how industry moves forward," Salahshoor said.