EVALUATING THERMAL ENERGY STORAGE IN THE COLUMBIA RIVER BASALTS FOR THE PURPOSES OF SEASONALLY HEATING OR COOLING DOWNTOWN PORTLAND, OREGON, USA

Under a U.S. Department of Energy funded study, 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. Early work by Gannett (1985) documented the use of the Columbia River Basalt (CRB) aquifers beneath downtown Portland for direct-use heating and cooling of buildings, identifying the key resource considerations. We build upon the work of Gannett, and the conceptual models of CRB hydrology within structurally complex terrains, developed by Lite and Grondin (1988) and Lite (2013), to formulate and quantitatively test the likelihood that Deep Direct-Use Thermal Energy Storage (DDU-TES) can be used for district heating or cooling for the Portland metropolitan area. 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 developed for this study 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. For the CRBs beneath 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.

REFERENCES

Gannett, M.W. “Ground water heat pump use in downtown Portland - resource considerations.” Solar Energy Association of Oregon, SEOGRAM, (1985), v. 4, n. 2, p. 6-9.

Lite, K.E, Jr., and Grondin, G.H., 1988, “Hydrogeology of the basalt aquifers near Mosier, Oregon—A groundwater resource assessment”: Oregon Water Resources Department Groundwater Report No. 33, 68 p. plus appendixes.

Lite, K.E., Jr., 2013, “The influence of depositional environment and landscape evolution on groundwater flow in Columbia River Basalt—Examples from Mosier, Oregon”, in Reidel, S.P., Camp, V.E., Ross, M.E., Wolff, J.A., Martin, B.S., Tolan, T.L., and Wells, R.E., eds., The Columbia River Flood Basalt Province: Geological Society of America Special Paper 497, p. 429–440, doi:10.1130/2013.2497(17).