Seasonal Thermal Energy Storage for Under-utilized Wind Energy

Photo of Austin Anderson, Casey Nolan, and Chris Varela (Team Leader) Students: Austin Anderson, Casey Nolan, and Chris Varela (Team Leader)

Sponsor: Austin Energy

Date: Spring 2010

Requirements:
The thermal energy storage system must be thermally effective, financially feasible, and environmentally sustainable. The cost of the system is evaluated as a pay-back-period based on the summer natural gas costs incurred by The University of Texas. Additionally, the discharge period was defined as being during the summer, from June 1 to September 31 yearly.

Problem:
Austin Energy tasked our group with determining the financial feasibility of using winter wind generated electricity to create a cold thermal mass, which would be stored and then used in the summer to supply The University of Texas at Austin summer chilling load.

Solution:
Aquifer Thermal Energy Storage (ATES) may be used to store and deliver thermal energy to The University of Texas. If the system charges for 213 days, 12 hours each day, a total of 54,300 tons of chilling is required. The costs associated with well drilling and component installation make the system financially feasible. However, specific aquifer characteristics are critical to the performance of the system; therefore, a hydrogeological survey of the area must be conducted to determine the well locations. A schematic representation of aquifer thermal energy storage is presented above. Pit thermal energy storage can be used to successfully store and deliver a source of cold. Using a charging period of 122 days, 12 hours each day, 47,473 tons of chilling through ice production can be achieved cost effectively; however, excavation costs make the system financially infeasible. Implementing a pit thermal energy storage system relies on finding existing volume-appropriate pits in order to reduce costs. A schematic representation of pit thermal energy storage is also presented above.

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Photo related to Seasonal Thermal Energy Storage for Under-utilized Wind Energy project
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