Geothermal heating and cooling technology isn't new—geothermal systems have been in use for more than 30 years in homes, businesses, commercial and institutional buildings. It can offer substantial operational savings over conventional methods of heating and cooling.

Yet, geothermal systems account for a relatively small percentage of the heating/cooling market, largely because their cost is higher than other systems, and many potential buyers perceive operational savings will take too long to pay back the initial investment.

However, that appears to be changing with the escalation of the past few years of costs of natural gas, electricity, and fuel oil, and the documented efficiencies of geothermal systems. And geothermal systems of today are much more efficient than earlier versions.

A report released in March by the Geothermal Energy Association (GEA) said there is strong growth in new geothermal power projects that is continuing today.

"There has been a 25 percent increase in new geothermal projects since August 2008, when the previous GEA report was released," said report author Kara Slack.

A geothermal system draws on the relatively stable temperature of the earth below its surface to provide energy-efficient heating and cooling. A geothermal heat pump (GHP)—also often called a ground source heat pump—inside the structure is connected to an underground HDPE pipe loop through which water or an antifreeze solution is circulated to exchange heat from the earth and the GHP. Large commercial and institutional buildings require multiple GHP units and loops.

Vertical drills are used to install vertical loops; pipe for horizontal loops can either be laid in trench, depending on the depth needed, or installed by horizontal directional drilling (HDD). In Moline, Illinois, QC Geothermal is finding strong demand for geothermal systems in the Quad Cities area and beyond. In the heating and air-conditioning business before expanding into the geothermal market, QC President Bruce Soukup installed the company's first GHP system, renting a trencher to install the underground loop.

"We discovered an opportunity and developed a niche in the geothermal market," said Soukup. "Our number of installations has increased year after year—the more energy became a concern, the more installations we did."

Demand reached the level that Soukup decided to establish QC Geothermal and made the decision to install loops rather than only sell and install GHP components.

"We started with one vertical drill, then added a horizontal directional drill in 2001," said Soukup. "We maintained a steady workload of residential geothermal work, and then began taking on commercial projects."

Soukup credits experience gained on residential installations for smoothing the transition to larger, more profitable contracts in the commercial marketplace. Today the geothermal workload is about 20 percent residential, 80 percent commercial. On commercial jobs, QC sometimes turnkeys the project; on other occasions the company subcontracts installation of the loops.

With increased commercial geothermal business, Soukup added another vertical drill and a new, larger directional drill.

Soukup said the use of directional drilling for commercial loops has increased significantly over the last three years. The HDD installation process permits the loop to be installed under driveways and walks; lawns, flower beds, and other landscaping; outbuildings, and other surface obstructions. Because excavation is minimized, restoration costs are reduced. Trenching usually is the option.

"Over the last three years, our use of directional drilling for commercial loops has gone up significantly," said Soukup. "We completed several commercial loops with our old drill, but needed one that was more productive and reliable."

The Ditch Witch JT3020 Mach 1 is a relatively compact, self-contained unit mounted on rubber tracks that enable it to move across both paved surfaces and grassy terrain with minimal surface disturbance. Powered by a 148-horsepower diesel engine, the JT3020 develops 30,000 pounds of pullback, 4,000 foot-pounds of spindle torque, and a maximum spindle speed of 225 rpm.

This drilling unit was used on one of QC's largest commercial geothermal projects, at Tiffin High School near Iowa City.

The project was designed for all underground loops to be horizontal, and all were installed by directional drilling. Portions of the loops were installed under the school's athletic complex, including the football stadium and soccer and baseball fields.

Soukup said 221 300-foot bores were made on the project with loops installed in three layers at 15-, 30-, and 35-foot depths. Loops were of 1-inch HDPE pipe, which was loaded on reels for installation. When pieces had to be joined, they were fused, never glued. (Soukup said most residential systems use 3/4-inch pipe for loops while commercial installations are either 1- or 1.25-inch pipe).

The drilling unit bored a 4.5-inch pilot hole, then pulled pipe back through without the need to backream. Soil was mostly clay, with layers of sand and gravel encountered in some areas.

The QC drilling crew averaged four bores per day and completed loop installation in five months. Pipes were stubbed into buildings, and the project's heating and cooling contractor hooked up pipes, completed interior piping, and connected the 50-plus GHP units.

For a time, said Soukup, there was the perception that geothermal systems could only be installed in new homes and buildings.

"But that is changing," he said, "as more property owners recognize the value of geothermal systems and that retrofits are practical. Directional drilling has played an important role in the increase of retrofit business, because loops can be installed without a lot of mess and can go under surface improvements. HDD is much cleaner than putting in vertical loops. With the directional drill, we just bring pipe into the basement and make the connections."

Soukup said that he is very pleased with the JT3020 Mach 1.

"We think it's the best machine out there," he said.

With more property owners recognizing the value of geothermal heating and cooling and the likelihood that fuel costs will continue to go up, Soukup is optimistic about the future.

"We stay busy," he said, "and we believe as stimulus money begins to come in, some of it will go for geothermal retrofits."

Most of QC's geothermal business comes through referrals and from contractors with whom the company has subcontracting experience.

"As the market grows, we are seeing some HDD specialists interested in loop work," said Soukup. "But we are well established, and some engineers now require that a contractor be pre-qualified to be considered on a project, and that gives us an advantage over drillers from other markets."