TT Asia Pacific, a part of the world wide Tracto-Technik Group of Companies, is very excited about geothermal radial drilling (GRD). Tracto-Technik has shown that this technology is successful. Geothermal Technology Manager Andreas Hagedorn will be at Trenchless Live 2010 to answer questions about GRD.

The pyramid connection, you may ask? Well, anyone travelling to Giza in Egypt will, not surprisingly, see pyramids. But when travelling to Lennestadt in the Sauerland region of Germany the pyramids surprise and delight. The energy concept is just as surprising.

The Sauerland pyramids are a local landmark, and are situated on a mountain overlooking the town of Meggen. The area, named the Galileo Park, is a modern, high-tech business and expo centre. Alternative medicine company Rayonex is based in three of the seven energy-efficient pyramids.

Rayonex owner Wolfgang Schmidt said “It is not a place for simple entertainment. It is in fact a place full of sophisticated attractions, intended to awaken the interest in new topics and encourage the mind to reflect on certain aspects.”

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Powering pyramids with geothermal energy

An innovative energy concept is now being used at the pyramids. Geothermal energy was selected for heating and cooling in the first pyramid, which was built in 2005. One of the reasons for this was the fact that gas was not available and oil was not wanted under any circumstances.

Additionally, Tracto-Technik had the necessary bore know-how, so the decision to go for geothermal energy was easy.

In Galileo Park the buildings are heated and cooled, along with the 200 square metres pond. In this case the innovative GRD technology was applied. A shaft was installed on the pond’s island, from where 10 bores of up to 50 m depths and 114 mm in diameter were produced radially. Water was used as a heat transfer medium inside the coaxial ground source heat exchangers. This is called direct heating and cooling, and does not need the addition of a heating pump to the whole circuit. The geothermal heating and cooling load is 15 kW.

The GRD bore rig has a great advantage when renewing heating systems in old buildings. The compact bore rig only requires a small set-up surface and causes minimal surface damage. A study carried out at Siegen University has shown that radial bores are especially energy efficient and have minimum running costs.

An animal enclosure was connected via an 8 kW air-water heating pump to the ground heater. The Sauerland pyramids are therefore operated with horizontal, vertical and radially-installed geothermal sondes, as well as being equipped with twin U-sondes. The heating load is 32.6 kW. The heating is direct, which means heat exchangers are not used. Instead, the brine volume from the pyramids is circulated into the mountain and vice-versa. As the area is situated on the filled ground of a disused mining site, a special focus during the bore process was set on boring through water-leading horizon as much as possible. This was intended to increase the high-extracting and regeneration performance.

Another bore method was applied to heat and cool the other pyramids. A total of nine vertical bores, each over 99 m (total: 881 m) were carried out with the vertical bore rig Geodrill 20 V from Tracto-Technik. After completion these bores were also equipped with double U-heat exchanger pipes (32 mm diameter). To be able to plan the ground source loop field, the pipe array was calculated in advance using the “Earth energy designer” software. The heating and cooling of the pyramids is steered from the energy supply station, the so-called “energy temple“. The 63 kW heating pump installed here provides a pleasant climate in all of the pyramids.

The pyramids are a first-class example of the benefits of geothermal energy combined with the use of the Geodrill 20V and show the huge potential worldwide for domestic applications.