Controls on deep direct-use thermal energy storage (DDU-TES) in the Portland Basin, Oregon, USA

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Abstract

Aquifer Thermal Energy Storage is being evaluated as a complementary technology to Deep Direct-Use for the Portland Basin, Oregon, USA. Aquifers can be used to efficiently distribute and store heat for seasonal use. The use of injection-extraction well pairs precludes the need to store or dispose of large volumes of pumped groundwater or to obtain a consumptive groundwater right. Injection temperatures vary seasonally, and well pairs can operate in continuous (single direction of flow) or cyclic (seasonal reversal of flow) modes. The target injection aquifers are the lowest Columbia River Basalt Group interflow zones, which are thermally and hydraulically separated from the overlying aquifer system, minimizing heat loss. A new aquifer thermal energy storage design tool allows assessment of thermal storage and recovery using: (1) system design parameters (e.g., well spacing and pumping rate), (2) thermal and hydraulic property values, and (3) regional groundwater flow rates. In continuous mode, extracted water temperature trends towards the flow-weighted average temperature of injected water over time, with the injected signal significantly lagged and damped. By controlling well spacing and temperature of delivered water (possibly using supplemental heating) continuous mode provides steady reliable warm water to end-users year-round. In cyclic mode, there is an advectively and conductively heated zone near the hot well and a cooled zone near the cool well, with temperatures substantially above and below the flow-weighted average injection temperature, respectively. In cyclic mode, during extraction, water temperatures start high or low, depending on the well, and temperatures trend towards the average injection temperature over the season. For the Columbia River Basalt Group in the Portland Basin, the quantity and quality of heat delivered depends most strongly on operational schedule, well spacing, mode of operation, and heterogeneity of the injection horizon.

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Additional publication details

Publication type Conference Paper
Publication Subtype Conference Paper
Title Controls on deep direct-use thermal energy storage (DDU-TES) in the Portland Basin, Oregon, USA
Volume 42
Year Published 2018
Language English
Publisher Geothermal Resources Council
Contributing office(s) Oregon Water Science Center
Description 36 p.
Larger Work Type Book
Larger Work Subtype Monograph
Larger Work Title Geothermal's role in today's energy : Geothermal Resources Council Annual Meeting (GRC 2018)
First page 132
Last page 168
Country United States
State Oregon
Other Geospatial Portland Basin