The Year of Geology 2016

Studying the core of geoenergy in more detail than before

Finland’s bedrock is an excellent heat source in each part of the country. Almost all households can utilise this enormous geoenergy battery and almost emission-free heating/cooling system with reasonable starting costs and small operating costs. Geoenergy is being studied continuously to allow its optimal use. Old inventions, like optical fibre cable in this case, may be of great use.

When a traditional sensor measures the underground temperature in one point, an optical fibre has measuring points at the interval of one metre. If there are, for example, multiple cables in a heat well that is 30 metres deep, which is the case in the DTS system studied by GTK, it is possible to obtain valuable temperature data from the distance of multiple kilometres at once. Optimisation of, for example, half a centigrade, means significant monetary gain in large construction projects that have multiple wells.

“In winter, we can get heat from the bedrock’s geoenergy battery, but in summer, we can transfer it back to the locations which, due to the bedrock geology and heat properties or the flow of groundwater cool down faster than usual,” says research assistant Ilkka Martinkauppi from GTK’s Geoenergy unit.

Originally the DTS (Distributed Temperature Sensing) method was developed for monitoring tunnels and oil and gas pipes.

“Optical fibre is more reliable and accurate than an electrical cable, because in the case of fire, measuring does not stop completely, but continues until the cable is cut.”

Students study the technology

Ilkka Martinkauppi and his colleagues spread the DTS competence to Finnish students. A heat well, fibre cables, and a measuring device for research and teaching purposes will be built on, for example, the new campus of the Metropolia University of Applied Sciences in Myllypuro, Helsinki.

The students of construction and HVAC technologies can learn how to use the system and also learn about the heat properties of soil and bedrock. Metropolia is very interested in and enthusiastic about the technology.

GTK studies and applies the DTS method also in monitoring the dam structures of mines and in surveying groundwater areas.