Green Building 101: Tapping into Geothermal Riches

The Nesjavellir Geothermal Power Plant in Þing...
Geothermal Plant in Iceland

If using a banking analogy for the untapped and clean geothermal energy our planet provides, we discover that the world lives on top of a remarkable energy safe deposit vault.

In 2008, geothermal power supplied less than one percent of the world’s energy. However by 2050 it is anticipated that geothermal power will meet between 10 and 20 percent of the world’s energy requirements, according to a report from Renewable Energy World.

Merline Van Dyke, a Colorado engineer and geothermal innovator says there are many different kinds of geothermal systems including some that rely on hot water from beneath the earth’s surface, and others that simply use the constant temperature of soil below the surface as a means of heating and cooling.

“What I’m interested in talking about are the efficient ones,” says Van Dyke. He began experimenting with making homes more efficient in 1994, building a home in the foothills west of Denver, using structural insulated panels.

Van Dyke is presently working with Sims Construction, a Denver builder, as they finish a three-story, 2,400 square-foot geothermal house that uses structural concrete insulated panels (SCIP) on the exterior to maintain efficient temperatures. Net result: R-40 insulation value, an electricity bill that will run half of a normal bill, and no need for natural gas.

Geothermal system from Amasond

The house is located in central Denver and features an Amasond geothermal system. Amasond, an Austrian-based company, provided a geothermal system where pipe was drilled to a non-water level of 118 feet, where the earth temperature was a constant 52 degrees Fahrenheit.

This past summer, Sims flew to Europe to participate in an Amasond training program. “I am very excited about how efficient this home is going to be,” Van Dyke says, pointing out it is the first such home in the area.

Understanding Geothermal Basics

Geothermal energy – or heat from the Earth – has been used in a variety of ways since the early annals of human life on this planet. Perhaps best, in this day and age, most geothermal energy is clean and sustainable, depending on what procedures are used.

Hydraulic fracturing of rock below the surface, a procedure used in oil and natural gas capture, is being explored as a way to obtain hot water, but the environmental impacts to this procedure are being questioned by some. Resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the Earth’s surface, and down even deeper to the extremely high temperatures of molten rock called magma.

Merline Van Dyke and Richard Sims at geothermal house in Denver

Van Dyke and Richard Sims used a geothermal heat pump system consists of a heat pump, an air delivery system (ductwork), and a system of pipes buried in the ground near the building (see photo).

In the winter, the heat pump removes heat from the heat exchanger and pumps it into the indoor air delivery system. In the summer, the process is reversed, and the heat pump moves heat from the indoor air into the heat exchanger.

The heat removed from the indoor air during the summer can also be used to provide a free source of hot water. The Department of Energy, working with the National Renewable Energy Lab (NREL) in Golden, CO undertakes ongoing research to develop and advance technologies for these geothermal applications:

  • Geothermal heat pumps use much less energy than conventional heating systems, since they draw heat from the ground. They are also more efficient when cooling your home.
  • Not only does this save energy and money, it reduces air pollution. The GEO Exchange is a trade association for geothermal heat pumps, an integral part of any geothermal system.

In modern direct-use systems, a well is drilled into a geothermal reservoir to provide a steady stream of hot water. The water is brought up through the well, and a mechanical system – piping, a heat exchanger, and controls – delivers the heat directly for its intended use. A disposal system then either injects the cooled water underground or disposes of it on the surface.

Geothermal Electricity

In 1911, the world’s first geothermal power plant had a capacity of 250 kilowatts. By 1975 the Larderello fields were capable of producing 405 megawatts of power. It was the world’s only industrial producer of geothermal electricity until 1958, when New Zealand built a plant in Wairakei. The Geysers Resort Hotel, California, was the site of the first geothermal power plant in the United States.

In 1960, Pacific Gas and Electric began operation of the first successful geothermal power plant in the United States at The Geysers. The largest group of geothermal power plants in the world – 21 in total – are now located at The Geysers in California.

The original turbine installed at The Geysers, lasted for more than 30 years, and produced 11 Megawatts of power. The Geysers currently produces over 750 Megawatts of power annually. Today, 69 geothermal power facilities are in operation at 18 sites around the United States, and geothermal power is generated in over 20 countries around the world.

Editor’s Note: Green Building Elements is launching a Green Building 101 Series which will be posted bi-weekly, on the 1st and 15th of every month. Take this challenge with us as we learn how to build sustainably from the ground up.