Geothermal heats up the Twin Cities


What do the Twin Cities and Iceland have in common? Well, literally speaking, in some Minnesotan winter months you might feel like you are living in an iced country. Actually, the Icelandic sea climate is much more moderate and there is rarely snow. Despite their differences, Minnesota and Iceland share at least one common ground: the use of geothermal energy.

Throughout Iceland about 90% of the population heat by geothermal. “A lot of people coming to Iceland are surprised because of that strange smell in the air. It’s the smell of sulphate originated by the many underground hot water sources across the country,” says Erlingur Óttar Thoroddsen, an Icelandic exchange student at Hamline University.

Iceland is located on what geologists call a “hot spot.” Due to the newness of the land itself (approximately 16-20 million years), the crust of the Earth is thin, which accounts for the huge number of hot springs around the country. In Iceland, these geothermal resources are used for heating, and also harnessed to generate electricity. The Icelandic profit highly from these natural resources. “Although living costs are high in Iceland and Reykjavik is considered to be one of the most expensive cities worldwide, we’ve got one thing that is very, very cheap, and that’s energy,” Erlingur says.

Unfortunately, the best geothermal resources around the world are concentrated in areas of volcanic activity and are not widely distributed. The main high temperature resources suitable for electric power generation are found only in Italy and Iceland. Most parts of Europe and the United States are dominated by intermediate- to low-temperature geothermal resources. These resources are more suitable for direct uses such as: space heating, district heating, greenhouses, bathing, and geothermal heat pumps dominate.

Compared to European cities in general and Icelandic cities in particular, the use of geothermal heating in the Twin Cities is still rare. Nevertheless, the Science House of the Science Museum, the Green Institute and a couple of residential houses use geothermal heat pumps to heat and cool the building.

The shallow ground of the earth maintains a nearly constant temperature between 50° and 60°F (10°-16°C). Like a cave, this ground temperature is warmer than the air above it in the winter and cooler than the air in the summer. Geothermal heat pumps take advantage of this resource to heat and cool buildings. Through a system of underground pipes, they transfer heat from the warmer earth to the building in the winter, and take the heat from the building in the summer and discharge it into the cooler ground. Depending on the geology of the area, the size of the home and the location of the home/property, different types of geothermal systems may be used.

The geothermal system at the Green Institute, which was installed in 1999, is a vertical system with 120 feet-deep wells. Out of one unit of electricity to run the pumps it produces three units of heating. Although the start-up costs were high, the system proves to be highly efficient. “At the beginning, we expected a nine-year payback, but since gas prices increased, the payback period was just five or four years,” Carl Nelson, Director of Community Energy at the Green Institute, explained.

Chris Shields, Editor and Deputy Communications Director of the think tank “Minnesota 2020,” and his wife just moved into their new, energy-efficient town home in South Minneapolis. Their home uses a geothermal ground source heat pump. “It’s been working great; we didn’t have to turn on the heat so far,” Shields said on DATE. “In fact, I turned the thermostat a few degrees cooler. I suppose this comes with the territory when you’re living in one of Minneapolis’ green homes.”

The most difficult part of geothermal heat pumps seems to be the installation. “It’s not like installing a furnace or something,” Carl Nelson says. The challenge is to find the appropriate size of the system and because of the technical knowledge and equipment needed to properly install the piping, it’s not a do-it-yourself project. Nevertheless, “as long as you properly install it, you don’t have problems,” Nelson says.

Although the use of geothermal in the Twin Cities won’t pave the way for living in an energy dreamland like Iceland, it’s at least one step toward a cheaper future.