Newspaper article Pittsburgh Post-Gazette (Pittsburgh, PA)

Finding Value in Mine Water State's Abandoned Mines a Potential Source of Energy

Newspaper article Pittsburgh Post-Gazette (Pittsburgh, PA)

Finding Value in Mine Water State's Abandoned Mines a Potential Source of Energy

Article excerpt

SCRANTON ? The nuns who founded Marywood University in 1915 paid the mining company that sold them the land to leave pillars of coal untouched beneath their campus to ensure that the ground wouldn't give way.

A century later, the school drilled two wells into the abandoned, flooded mine to draw water. The water circulates through a system that cools the studios in its environmentally sustainable School of Architecture building.

A college built on a coal mine learns to accommodate the void beneath it.

The same might be said of cities and states.

Pennsylvania's abandoned mines could be a massive source of renewable energy, extracted not from coal but from the water flooding the unused caverns. The state's subterranean pools are large, reliably warm and generally close to population centers, which makes them ideal geothermal resources for heating and cooling buildings.

Michael Korb, a program manager in the Pennsylvania Department of Environmental Protection's Bureau of Abandoned Mine Reclamation, wrote a paper about the potential in 2012: "With more than 3 million people living in and around cities like Pittsburgh, Scranton, Wilkes- Barre, Johnstown and Hazleton located over known mine pools," he wrote, "the possibilities for use of geothermal heat from mine pools seem to be unlimited."

Rich with possibilities

Heating and cooling buildings with mine water makes elegant use of a dirty problem.

A flooded mine is "just a reserve of heat," Mr. Korb said. "It is 55 degrees, and it is not going to change temperature because there is so much of it."

Mine water is typically warmer than the air in winter and cooler than the air in summer. Geothermal systems that tap into the pools generally use heat exchangers to draw warmth from the water to heat buildings or sink the heat of the indoor air into the water to cool buildings.

The temperature of the mine water is not far from the temperature you want inside a room, which makes a geothermal system more efficient than a heat pump that relies on air.

"I have a heat pump at home," Mr. Korb said. "When it gets down to freezing or below, it works pretty hard to exchange that air to make it 70 degrees. But it is much easier to make 55-degree air into 70-degree air."

The possibilities are particularly plentiful in Southwestern Pennsylvania.

In 2006, researchers with the National Energy Technology Laboratory evaluated the geothermal potential of the more than 1 trillion gallons of water stored in the Pittsburgh coal seam, which stretches through parts of Pennsylvania, West Virginia and Ohio. About 4 percent of the water ? 50 billion gallons ? is discharged each year at the surface, either at treatment plants or at legacy outfalls where the untreated mine drainage pollutes waterways.

The discharged volume alone could be used to heat and cool about 40 million square feet of building space, the researchers found, or the equivalent of about 20,000 homes. Tapping into the reservoir, they wrote, would allow 10 times as many homes to be heated and cooled.

The energy and pollution savings would also be substantial. If 20,000 homes above the seam used mine water geothermal instead of standard electrical heating and cooling, the researchers found, it would save 437,000 megawatt hours each year and cut annual sulfur dioxide and nitrogen oxides emissions by 2,100 and 920 metric tons.

At the time, they calculated that geothermal heat pump systems using mine water would reduce annual heating costs by nearly 70 percent and cooling costs by up to 50 percent compared to conventional methods using natural gas, heating oil or standard air conditioning. …

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