New Report Illuminates Geothermal Cooling Potential in Hawaii

Assist CleanTechnica’s work via a Substack subscription or on Stripe.

College of Hawaii at Manoa and Lawrence Berkeley Nationwide Laboratory Teamed up To Analyze Feasibility of Geothermal Cooling Applied sciences

By Justin Daugherty, NLR

In areas with geologically latest volcanic exercise and ample underground water circulation, just like the Hawaiian Islands, geothermal power applied sciences current choices to reinforce the electrical grid.

To analyze constructing cooling and power effectivity choices, the College of Hawaii at Manoa’s Hawaii Groundwater and Geothermal Assets Heart collaborated with scientists at Lawrence Berkeley Nationwide Laboratory via the U.S. Division of Power’s Power Know-how Innovation Partnership Undertaking (ETIPP).

Managed by the Nationwide Laboratory of the Rockies (NLR), previously generally known as NREL, ETIPP helps distant, coastal, and island communities with technical help and power planning to assist them construct extra dependable and inexpensive power methods. Communities apply for as much as 24 months of technical help, and people communities drive the scopes and focuses of their power tasks.

College of Hawaii at Manoa joined this system in 2022 with a want to discover geothermal choices, and a brand new report from this venture particulars the feasibility of growing shallow floor warmth exchangers (GHEs) throughout Oahu and at a selected web site on the island for cooling.

Geothermal warmth pumps reap the benefits of comparatively fixed temperatures slightly below the earth’s floor, utilizing GHEs to alternate warmth with the earth. By means of a system of looping pipes within the shallow floor, GHEs can transfer warmth from a heat place to a cooler place, like how a fridge features.

“Excessive-temperature geothermal, which requires deep drilling, is required to provide electrical energy, however low-temperature geothermal comparable to GHEs, which could be accessed a lot nearer the bottom floor, can be utilized for constructing heating and cooling, vastly lessening masses on the electrical grid,” mentioned Lawrence Berkeley Nationwide Laboratory’s Christine Doughty, employees scientist.

“I imagine each kinds of geothermal have potential to be an asset to Hawaii,” added Nicole Lautze, founder and director of the Hawaii Groundwater and Geothermal Assets Heart.

Figuring out Geothermal Cooling Favorability in Hawaii

In open-loop geothermal methods, wells are drilled to extract and inject groundwater, permitting the motion of thermal warmth to and from the earth. These GHEs use cooler floor water from exterior the system for the cooling course of and expel the hotter water afterward.

In distinction, closed-loop GHE methods regularly flow into a heat-transfer resolution via pipes, which transfers warmth to and from the bottom by way of thermal conduction. Groundwater must have temperatures which are low sufficient to successfully cool buildings, and groundwater circulation in a GHE system works to take away built-up warmth.

Hawaii has far better wants for cooling than for heating—which means that GHEs would add warmth to the subsurface and trigger the methods to not operate as desired. That’s the place groundwater is available in: It replaces heated water from the boreholes and maintains the performance of the GHE system. Enough groundwater circulation, then, is important to the issues for GHE deployment. GHE methods is probably not deployed in areas with restricted watersheds or the place there may be subsurface manufacturing of freshwater. Due to this fact, closed-loop methods could also be a extra cheap possibility in some areas.

Quite a few components assist decide whether or not a group or enterprise could take into account GHEs. Areas with older houses could lack environment friendly power methods, and a few organizations, like faculties or authorities buildings, could prioritize extra adaptive heating and cooling. Cultural issues are additionally crucial, and a brand new NLR report incorporates Hawaii communities’ views on geothermal.

Financial components are one other massive consideration, with the expense of deploying a system versus power financial savings taking part in into general value. Modeling revealed that electrical energy and power switch demand decreased, and such reductions contributed to value financial savings. Longer mortgage phrases could assist ease deployment bills for geothermal methods.

ETIPP researchers factored the above parameters into their evaluation to develop favorability maps for closed-loop and open-loop GHE methods. They used particular geographic info system layers with 11 attributes—together with elevation, geology, and soil permeability—to develop an general favorability map for GHEs on Oahu.

For the site-specific feasibility evaluation on the College of Hawaii at Manoa’s Stan Sheriff Heart, researchers used a hydrogeologic mannequin to investigate groundwater circulation of a closed-loop system on the web site. Restrictions on water high quality—mandating that groundwater should be left in its pure state—diminished the out there space for GHE system deployment throughout the island, whereas many coastal areas confirmed excessive favorability. Overlays exhibiting potential clients and restricted areas sharpened the maps.

Geothermal Cooling Potential at College of Hawaii at Manoa

From the island-wide evaluation, ETIPP evaluation homed in and located that the Stan Sheriff Heart on the College of Hawaii at Manoa, a constructing with a excessive cooling load in an space with numerous open house surrounding it, might make an excellent candidate for site-specific evaluation of GHE know-how.

Researchers used a hydrogeologic mannequin to investigate a possible closed-loop system on the web site. They modeled groundwater and warmth circulation, analyzed subsurface warmth circulation, and accomplished a techno-economic evaluation.

Evaluation with out groundwater circulation confirmed that the GHE system could function usually within the first yr, however warmth buildup would improve water temperatures considerably after that, and with out groundwater to brush warmth away, there could be elevated chiller demand in years two via six. Modeling that integrated groundwater circulation—with related circumstances because the Stan Sheriff Heart—confirmed that warmth could be successfully swept away from the borefield, which might allow profitable GHE operation for no less than 10 years. Thus, together with groundwater in evaluation and planning—coupled with low curiosity mortgage charges and excessive capital funding—could present financial advantages to the college.

Chilly seawater could also be an possibility for cooling-source methods, the evaluation concluded, and such a system already operates on the Pure Power Laboratory of Hawaii. The report authors inspired additional examine.

As in Hawaii, ETIPP continues to assist communities discover geothermal and different applied sciences to assist meet their power wants via in-depth, collaborative investigation of potential options.

“This ETIPP venture established a powerful collaboration with LBNL and the muse for what I hope is extra grant funding to discover the potential of GHEs on the UHM campus and throughout the state to chill buildings and scale back load on Hawaii’s grid,” Lautze mentioned.

The U.S. Division of Power’s Power Know-how Innovation Partnership Undertaking (ETIPP) is a community-led technical assist program for coastal, distant, and island communities to entry distinctive options and improve power reliability. By uniting federal companies, nationwide laboratories, regional organizations, and group stakeholders, ETIPP offers tailor-made technical assist to assist communities obtain inexpensive, dependable options to their power system challenges. This collaborative mannequin leverages the mixed experience and assets of its companions to ship complete, sensible options that align with native wants. Be taught extra about ETIPP.