Advocates for geothermal energy say that the path of destruction cut by Hurricane Sandy, which unearthed fuel tanks, ravaged cooling towers and battered air-conditioners, has already persuaded some building owners to switch to geothermal systems that use underground pipes to harness the earth’s energy for heating and cooling buildings.
Andrea Mohin/The New York Times
The geothermal energy system at the Brooklyn Children’s Museum, installed in 2007 at a cost of $675,000.
“We’re seeing dozens of these half-empty and empty oil tanks just popping up all over the place in the flooded areas,” said David E. Reardon, the manager of geothermal drilling for the Miller Environmental Group, an environmental response, remediation and restoration services company based in Calverton on Long Island that has been involved in poststorm environmental cleanup throughout the region.
“Those tanks become buoyant in all that water,” he said. But since geothermal systems don’t use fossil fuels or mechanical systems that are exposed to the elements, Mr. Reardon said, he started fielding calls from people asking for estimates on geothermal systems just days after the storm. “Often it’s a case where they were considering doing it, but were waiting for something to finally no longer be able to be repaired,” he said, and the storm has ended that wait.
Geothermal energy systems, common in countries like Iceland and China, use the constant temperature of the earth to heat and cool buildings.
Geothermal wells are dug to a depth where the earth regulates the temperature of water or a liquid circulating through the system. Geothermal systems may require one well or dozens to regulate a building’s temperature, depending on the size of a building and type of system installed. While the systems are called wells, they are actually an underground network of pipes connected to heat pumps to circulate water or some other liquid.
Because digging geothermal wells can be expensive and logistically difficult, the systems have been slow to catch on in New York City. Yet, according to the Rockefeller Foundation and DB Climate Change Advisors, “buildings consume approximately 40 percent of the world’s primary energy and are responsible for 40 percent of global carbon emissions,” said Jack DiEnna, the executive director of the Geothermal Heat Pump National and International Initiative, based in Washington.
Installing a geothermal system can significantly reduce a building’s carbon footprint, and over the last decade, the number of geothermal heat pump systems in the city has grown steadily. More geothermal systems are installed in New York, New Jersey and Pennsylvania than anywhere else in the United States.
Most systems are being installed in institutional buildings, multifamily residential buildings and relatively small commercial buildings. There have been systems installed by several prominent organizations and sites in the city, including the American Institute of Architects, the Times Square TKTS Booth, the Brooklyn Children’s Museum, the Queens Botanical Garden and the Bronx Zoo Lion House. In some of the outer boroughs and the suburbs, geothermal systems for single-family homes are also becoming more popular.
In all, more than 100 geothermal projects are in operation in the five boroughs, and about 90 percent of those projects are what are known as closed loop vertical bore systems, Mr. DiEnna said. A closed loop system is sealed from the ground and liquids are reused within the system, while an open loop system has discharge water it releases into a ground well or surface water.
Because building sites in the city, particularly Manhattan, tend to be small, the wells tend to be vertical, just like the buildings. Manhattan is not an ideal location for geothermal heat pump systems, because the wells must go so deep — to depths of roughly 1,500 feet — to reach the volume of land necessary to provide a constant temperature. In other areas with more available land, a geothermal heat pump system can be more spread out and much shallower, making it less costly to dig.
Elsewhere, larger scale geothermal projects known as enhanced geothermal systems have raised serious concerns because these larger power-production projects involve drilling wells down to tens of thousands of feet and fracturing the bedrock so water can be injected to create steam.
A few years ago, a project in Switzerland was shut down after it caused small earthquakes, and another project in Northern California was also stopped because of similar concerns. But the static, small-scale geothermal heat pump systems installed in the New York area bear little relation to these projects, said Daniel P. Schrag, a professor of geology and director of the Center for the Environment at Harvard.
Square Feet: Geothermal Energy Advocates Hope Systems Get a Second Look
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Square Feet: Geothermal Energy Advocates Hope Systems Get a Second Look
