Conversion Tower for Dispatchable Solar Power

Conversion Tower for Dispatchable Solar Power

Lakewood, Colorado
Project Term:
01/11/2012 - 07/31/2014

Critical Need:

There is a critical need to find efficient, cost-effective thermal energy storage solutions to maximize the use of domestic solar and nuclear energy resources. Most utility-scale solar power plants only run at about 25% of their capacity because they can't generate power at night—thermal energy storage makes it possible to increase this capacity to up to 60-75%. Similarly, nuclear power plants produce a constant output of power—thermal energy storage could help increase this output during times of critical peak demand.

Project Innovation + Advantages:

Abengoa Solar is developing a high-efficiency solar-electric conversion tower to enable low-cost, fully dispatchable solar energy generation. Abengoa's conversion tower utilizes new system architecture and a two-phase thermal energy storage media with an efficient supercritical carbon dioxide (CO2) power cycle. The company is using a high-temperature heat-transfer fluid with a phase change in between its hot and cold operating temperature. The fluid serves as a heat storage material and is cheaper and more efficient than conventional heat-storage materials, like molten salt. It also allows the use of a high heat flux solar receiver, advanced high thermal energy density storage, and more efficient power cycles.

Potential Impact:

If successful, Abengoa would reduce the cost of solar energy generation by 30% compared to existing state-of-the-art storage technologies—significantly reducing the cost of renewable solar electricity.


Cost-effective thermal energy storage would enable increased use of domestic energy resources like solar and nuclear—strengthening the nation's energy security.


Cost-effective thermal energy power generation could help decrease fossil fuel-based electricity use and harmful emissions from coal-burning power plants.


Thermal energy storage systems could make it less expensive to generate power from nuclear and renewable solar energy, which in turn could help stabilize electricity rates for consumers.


ARPA-E Program Director:
Dr. James Klausner
Press and General Inquiries Email:


Barber Nichols
Impact Technology Development
Sandia National Laboratory

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