DER-Grid Edge, Energy Storage, Generation, Natural Gas

Energy Cast Podcast: Understanding compressed air energy storage

CAES Schematic
Apex CAES facility near Palestine, TX will provide 324 MW, 15K MWh of energy, using renewable energy to pump compressed air into an underground salt dome storage cavern.

Energy Cast is a podcast featuring some of the top experts across all links in the energy industry chain, including electric vehicles, renewables, generation and more! Jay Dauenhauer created the show and has been hosting Energy Cast for several years.

Click below to listen to the full episode:

After working over a year and a half to get a Compressed Air Energy Storage (CAES) guest on the program, I was turned on to Apex Compressed Air Energy Storage in Houston, who is developing a 15K MWh, 324MW facility near Palestine, TX.

Once complete in 2022, the Bethel Energy Center will be the largest energy storage facility on earth.  Not only will it provide energy comparable to a conventional power plant, it will be able to run up to 48 hours, providing a storage solution that no other technology can match.

Our guest, Jack Farley, Apex President & CEO, says the largest cost advantage for CAES is the storage media which has an upfront cost at around $2/kW-hour, compared to batteries which fall in the $200-250/kW-hour range.  The key, he says are the improved equipment and its 30-year lifespan, with virtually no limits on the number of cycles the facility can run.

Compared to 5-10K cycles for a lithium ion battery, cost savings with CAES are clear.  Jack also points out that Bethel will have more storage potential than all battery storage in California combined.

The technology operates a lot like an air compressor.  Air is pumped into a cavern, and then released through a turbine which spins a generator.  The Bethel project will use an existing salt dome formation, which has stored natural gas for 25 years.

Salt domes are prevalent all over the world and have been storing hydrocarbons for years.  Growing up in Louisiana, we were proud to be home to the Strategic Petroleum Reserve, which also relies on salt domes for storage.

Jack says rather than write new regulations, Bethel will operate under the same parameters as a natural gas salt dome storage facility, up to about 3,000 psia.  He says the key to keeping the facility “healthy” is ensuring the cavern remains under a minimum pressure at all times, otherwise the cavern, about 3,500 below the surface, will begin to collapse on itself.

Rather than pay out over 48 hours, Jack says Bethel will typically charge 10-16 hours and discharge 10-14 hours each day.  In cases such as severe weather, then the facility would operate up to 48 hours.

He says the rapid rise of renewable energy in Texas has made a project like this possible.  A CAES or any other storage facility makes money by exploiting the spread in power prices over the course of a day, which can vary between $20 and $46 per MW/h.

In addition, Apex can provide “Flexibility services” such as Interruption capability, Ramping, and Spinning reserves.

I asked him how repeatable this technology is.  He says that salt domes and “bedded salt” formations can be found in every region in the U.S. except Florida and the Northeast.  These formations are found all over the globe in Germany, U.K., China, and Mexico.  Hard rock mines are also suitable, and if the formation is deep enough, maybe even spent underground coal seams. (This podcast originally aired in April 2019.)

Dauenhauer is a member of the DISTRIBUTECH International advisory committees. Clarion Energy is the parent company of DISTRIBUTECH.

We have postponed DISTRIBUTECH to March 30-April 1, 2021 and plan to hold it in conjunction with POWERGEN International in Orlando, Florida.


Energy Cast Podcast is hosted biweekly by Jay Dauenhauer.

Learn more about the podcast here.

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