Northwest Energy Association

NWEA Speaker Program for 2018-2019

Thursday, May 23, 2019 Portland State Student Presentations

Assessing the Feasibility of Deep Direct-Use Thermal Energy Storage (DDU-TES) in the Portland Basin

Darby Scanlon, Ellen Svadlenak, Alison Horst

Portland State University, Department of Geology

The Columbia River Basalt Group (CRBG) in the Portland basin is being assessed for thermal energy storage as part of a US DOE-sponsored Deep Direct-Use feasibility study. As part of this assessment, a 3D digital geologic model was constructed to define the location of energy storage strata and its thermal relation to other major geologic units. We modeled deformation of the CRBG through space and time using well log, seismic, outcrop, and potential fields (aeromagnetic, gravity) data. A cross section through the proposed well locations in the South Waterfront area along the Willamette River show a progressive shallowing of CRBG to the south, where Eocene aged basalt of Waverly Heights is exposed.

Several, potentially hazardous, northwest striking faults in and around the Portland basin are classified as Quaternary active by the USGS, but little is known about their Holocene activity. We investigated the Gales Creek fault through paleoseismic trenching, and we our results indicate there have been two surface-rupturing earthquakes in the last 8,000 years, meaning this fault is Holocene active. As part of the seismic and structural hazard analysis of this study, we compiled information on Quaternary active faults in the study area to use as inputs in the seismo-tectonic model of the Portland basin. We used analog studies to address the risk of induced seismicity with DDU-TES wells and used hazard maps from DOGAMI to assess geologic hazard and risk to infrastructure. Although there are active faults in the study area, knowing the potential hazard, as well as the geometry and characteristics of these faults, has been important in determining where a suitable location would be for these wells. 

Though a promising technology, DDU-TES cycles may trigger or accelerate mineral dissolution and precipitation reactions, particularly at elevated temperatures. This may alter aquifer porosity and permeability and result in scale formation in heat exchange systems that reduces the thermal storage-and-release efficiency. The amount of mineral precipitation can vary depending on the source water composition. Geochemical reaction modeling of native waters at both ambient and elevated temperatures suggests mineral precipitation is greatest under open system conditions, and above 50C for all potential source waters. This is supported by thermal batch reaction experiments simulating TES on a smaller scale. Both thermal experiments and modeling indicate that calcite, amorphous silica, and smectite clay are the primary minerals of concern regarding scale formation and aquifer plugging. 

PSU/USGS Bag Lunch Seminar Series of Interest to NWEA Members:

The Portland State Geology Department and the USGS Hydrology Section hold a joint seminar at noon every Tuesday during the Spring Term. This year Dr. Henry Posmentier will be speaking on May 28. His topic is "Fluvial Systems in Time and Space: Highlighting the Value of 3D Seismic. The seminar website is found here:

The NWEA is pleased to announce that it is a sponsor of the 2019 Northwest Climate Conference.

The meeting is held every there years. The next meeting will be held in Portland on October 18-20.

Further information can found on the conference website: