Using mother earth to heat and cool structures has long been an attractive option. It has not quite reached its potential, according to experts, because of high upfront costs and a lack of awareness among those who could benefit from the approach.
It is now time to give geothermal heating and cooling a second look. The technology, which has several slightly different names, takes advantage of the fact that near the surface of the earth – as little as 10 feet underground, according to experts – the temperatures consistently are between 50 degrees and 60 degrees Fahrenheit. This fact of
Utilities are using the technology. In the United States, the lion’s share of activity is on the west coast. Ken Silverstein, the Editor-in-Chief of Business Sector Media — the publisher of Energy Manager Today and Environmental Leader — wrote at Forbes two years ago that 80 percent of the utility-based geothermal activity in the United States is in California.
The approach is the same for all proponents of the technology — which can be industrial or commercial facilities and homes as well as utilities. For cooling, a sealed water pipe runs through the earth or the taps into an underground water source if it is available. This water is used to cool the structure above. In winter, structures are heated by using the same pipes to pump heat out of the building and transfer it into the ground.
Persistence Market Research is preparing a report on the non-utility market market. The research, which will be released in September, says that the market is segmented into domestic, commercial and industrial categories. There are four approaches: Ground heat exchange, direct heat exchange, open loop systems and closed loop systems. The latter category is divided into vertical, horizontal, radial, directional and pond subcategories. As of 2013, the largest segment was domestic and the fastest growing was closed loop.
At Bay Journal, Jeff Day looks at heat pumps mostly from the residential perspective. There are two types – air source and ground source (also known as geothermal) heat pumps. They also are appropriate for larger structures, he writes:
The Montgomery County, MD, school system, with 154,000 students and 202 schools, has been putting them in new schools since 2001, spokesman Derek G. Turner said. The system’s facilities department estimates that geo-exchange systems are 20–25 percent more efficient than conventional systems, Turner said. The story offers a nice graphic showing four approaches to how piping is installed underground.
A piece posted by The Observer, which covers New York City, is perhaps a bit overly optimistic about the potential for ground source heat pumps. But it makes a good case for the approach. It is interesting that St. Patrick’s Cathedral, one of the city’s icons, is heated and cooled by geothermal heating and cooling.
Bill Nowack is the executive director of NY-GEO, and an expert in geothermal energy. According to one estimate he shared with me, between 80 and 90 percent of buildings can be heated by ground source heat pumps. It is not for every part of the city and will be easiest to incorporate in the outer boroughs and more residential areas without existing underground infrastructures. An estimate by John Rhyner—a licensed professional geologist—showed that almost all of Staten Island, 70 percent of Queens, and half of Brooklyn residential footage could be heated with this technology.
The drawback, the Persistence Market Research study will say, is high installation costs. That obstacle is followed by unawareness and low confidence in the benefits of the approach, lack of technical progress or a decline in overall costs. Bad press – such as problems with condensation generated by a geothermal system at a new state penitentiary in Fort Madison, IA – certainly isn’t helpful.
Geothermal heating and cooling is not particularly new. It is an option that generates some attention when it is employed (for instance, for Buchanan & Hall’s new facility in the Stratford Wright Business Park in Ontario and new homes in Norton Commons’ North Village in the Louisville suburb of Prospect, KY).