Eric Wesoff

Ausra and Thermal Energy Storage July 28, 2008 at 8:20 AM

Ausra has a proprietary Thermal Energy Storage method and the company is not talking about it. However, insiders tell me that storage material is being mined and shipped for Ausra on a huge scale.

Thermal Energy Storage (TES) can allow parabolic trough power plants to store solar thermal energy at peak solar hours and to dispatch the power when it’s needed. According to NREL, TES can allow parabolic trough power plants to reach annual capacity factors of up to 70 percent (versus 25 percent without thermal storage.)

Josef Eichhammer of Solar Millenium spoke about molten salt thermal storage at a panel I moderated at Intersolar and I blogged about it here. The company is building molten salt storage on a massive scale. It is a proven, reliable, non-toxic material and construction is underway at a number of molten-salt TES systems around the world, notably the Andasol facility in Granada, Spain.

Also at Intersolar in San Francisco, Ausra’s Chief Development Officer Robert Morgan mentioned that Ausra was working on a thermal storage technology that was not molten salt-based. He would not be specific about the storage medium.

I asked Glen Davis, Ausra’s EVP, to comment and he was non-communicative on the subject as well. (Although, he was plenty communicative about financing solar thermal projects though.)

Anyway that leaves me to guess what the company anticipates using to store thermal energy in their trough-based solar thermal system. One can store the energy directly in the steam or oil collector medium but that’s not too efficient.  NREL talks about the use of molten salt, cement or concrete, a thermocline, or PCM (Phase Change Material).

Here are some comparisons of these technologies. And a brief presentation on concrete storage can be found here.

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