
Houston startup plans to store wind energy underground - phr4ts
http://www.houstonchronicle.com/business/columnists/tomlinson/article/Houston-startup-plans-to-store-wind-energy-11272381.php
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samcheng
The article, and the comments here, are missing an important fact that really
helps clarify how these compressed-air energy storage systems work:

These systems use the compressed air as input into a natural gas turbine. You
can think of the underground storage as a giant intercooler that stores the
output of the first (compressor) half of a natural gas turbine, and then feeds
that compressed air into the second (combustion) half.

See a good explanation here: [http://energystorage.org/compressed-air-energy-
storage-caes](http://energystorage.org/compressed-air-energy-storage-caes)

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c-smile
"Apex will need a small amount of natural gas to heat the air it compresses to
maximize turbine output."

As far as I understand they need to heat up the turbine as air (a gas) cools
down upon (adiabatic) expansion.

And while accumulating / compressing air in ground lacunae, pumping it into
the storage, we are just heating up the ground.

Am I right in my understanding of the process thermodynamic ?

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samcheng
You are correct, the article has a typo and should state 'decompresses'
instead of 'compresses.'

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Black-Plaid
> and the system can fill the cavern with air while generating electricity.
> You can't charge and discharge a battery at the same time.

Umm, does this seem as pointless to everyone everyone else as me?

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Dylan16807
It's a very strange statement. There's no reason to do it, and you can easily
do it anyway with your _multiple_ batteries.

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taylorhou
Glad to see something about houston on HN regardless of what the startup is
doing! Woot woot

