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Thermal conductivity of seafloor

PTB presents a new measuring method and instrument at the Sensor+Test trade fair in Nuremberg


Probably, the first German offshore wind facility will be put into operation yet in 2009. Then, 12 giant wind turbines out at the North Sea will turn near the isle of Borkum, each one generating 5 megawatts of power, the largest worldwide. The electrical current they will produce will be conveyed over a distance of 45 km past Norderney to the mainland, at a depth of two to three meters buried in the seafloor. In addition to many other technical challenges making the whole project controversial, a metrological problem all around this cable would have to be solved: how can the thermal conductivity of the seafloor be determined accurately enough to be able to predict the later influences of temperature on the buried cable? The seafloor contains great quantities of pebble gravels which create many inhomogeneities and, naturally water which additionally interferes with any measurement due to convection. After several renowned test institutes had given up in the face of these obstacles , the commissioned engineering company turned to the measurement experts of the Physikalisch-Technische Bundesanstalt (PTB). And they were able to help. Using a method they had recently developed themselves, they successfully measured the thermal conductivity of several seafloor samples at the required accuracy. The instrument had already proven its worth in in-situ measurements of river sediments of the Spreewald situated near the German town of Lübben. , The measuring instrument is all-purpose. A manufacturer will soon be bringing it on the market under licence. First of all, it will be presented from 26 to 28 May 2009 at the Sensor&Test trade fair in Nuremberg at the PTB booth (Hall 12, Stand 582).

Dr. Ulf Hammerschmidt, PTB Working Group 1.74 "Thermal Conductivity, Heat transport",
Tel.: +49 531 592 3211, e-mail: ulf.hammerschmidt(at)ptb.de

Dipl.-Ing. Vladislav Meier, "Development of new Thermal Sensors",
Tel.: +49 531 592 3217, e-mail: vladislav.meier(at)ptb.de