a geothermal greenhouse in Iceland

Direct Heat Use

Geothermal energy is among the oldest, most versatile, and most common ways to use Earth’s natural heat. The simplest uses of geothermal energy harness heat or steam as it leaves the ground: bathing and thermal spas, space heating, greenhouses, district heating systems, and drying—all of which date to prehistoric human civilizations.

Direct Use

Low-grade geothermal resources (i.e., those cooler than 150°C or unable to support power generation) are abundant. The United States Geological Survey estimates that low-grade systems could produce nearly three times the annual thermal needs for residential heating, cooking, and clothes drying. This rises to eight times the thermal needs for these applications when incorporating sedimentary resources.

Direct-use applications extend beyond heating to include greenhouses, aquaculture, food processing, and industrial uses, such as pulp and paper processing and drying construction materials.

More Than Heat

The City of Boise, Idaho, has operated a municipal geothermal system since the late 19th century. Today, it heats more than 6 million square feet of downtown building space and has the potential to expand both its footprint and its services. The accompanying video (produced by the City of Boise) illustrates the potential of a large-scale direct‑use geothermal system.

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Project Spotlight

Mokai Power Station Greenhouse

RESPEC engineers led a feasibility study and construction of a geothermal greenhouse next to the Mokai Power Station.

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Direct Use Prefeasibility Study

RESPEC conducted a prefeasibility study for a district heating system for the city of Estevan, Saskatchewan.

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Tasman Pulp and Power

To replace an old gas boiler, RESPEC staff helped manage construction and operations of a new geothermal system.

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Image: Adobe Stock

Geothermal Heat Pumps

The thermal storage capacity of soil, rock, and water near the surface is a vast, highly accessible geothermal resource. Though it may not be hot, the nearly constant year-round temperature within about 10 meters of the surface can provide a heat-exchange medium for efficient, low-cost heating and cooling of residential and commercial buildings. Geothermal heat pumps (GHPs), or ground-source heat pumps, take advantage of consistent shallow-earth temperatures. A GHP system includes a group of buried or submerged pipes to provide heat exchange, a forced-air and/or radiant delivery system, and a heat pump to move thermal energy between the system and the ground. These systems can be installed almost anywhere and can provide hot water, heating, and cooling.

RESPEC has widespread experience designing and overseeing the construction of both vertical and horizontal loop fields and their accompanying heat pump system infrastructure. RESPEC has provided closed-loop ground coupled heat pump systems for schools, office buildings, aquatic centers, airports, and more.

Project Spotlight

Geothermal Ground Loop

RESPEC oversaw drilling and construction for a geothermal ground loop serving a new 500-bed, multistory dormitory at the University at Albany.

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Juneau International Airport

RESPEC has helped modernize several airport buildings, including installing geothermal systems to aid in heating, cooling, and snow removal.

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Mendenhall Valley Library

Completed in 2015, this 21,000-square-foot, LEED Gold Certified public library is heated and cooled via 18 vertical boreholes.

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