MUSE pilot area activities – RESULTS – #2 Linköping

Multidiciplinary field measurements for a High Temperature Energy Storage site (HT-BTES) at Linköping Sweden

Mikael Erlstroem (SGU), 22 April 2021

The heat storage at Linköping aims to shift around 50 MWh excess heat from a waste incineration plant during the summer to the winter season. The storage design includes up to 1500 wells to 300 m depth in the crystalline basement. The performance and economic feasibility rely strongly on the geological prerequisites such as fracturing, ground water conditions, thermal properties, and Quaternary overburden. To get a high level of confidence on the geological conditions is a challenging task and requires a toolbox with various methods.

The MUSE project has allowed us, during three field visits in 2019 and 2020, to test the applicability of various geophysical methods in an around 2 km2 large area at Linköping. Ground geophysical surveys with magnetometer and VLF combined with borehole investigations, including TRT and DTRT measurements, geophysical wireline logging, thermal conductivity measurements and mapping of fractures with drones have been tested (fig. 1 & 2).

The overall aims have been:

  • to evaluate the applicability of different field methods, not typically applied in pre-investigations,
  • to exemplify how multi-disciplinary pre-investigations can support the placing and design of a HT-BTES system,
  • to provide guidance on how and what type of geological information is possible to select for a large-scale geothermal system in a crystalline bedrock setting.

The magnetometry and VLF surveys, in combination with fracture mapping and analysis of the thermal conductivity, have proven cost-efficient methods to map different rock types, fracture zones and orientation of fractures (fig. 3 & 4). The results have provided guidance to a favourable location of the HT-BTES within the pilot area (fig. 4). An important outcome is also that a pre-investigation strategy based only on scattered well observations is inadequate when assessing large scale HT-BTES systems in anisotropic crystalline bedrock. The study has proven that a toolbox with various tested methods give prerequisites for a tailored pre-investigation strategy related to the geological setting and system requirements.

Fig 1. Overview of the investigations performed in the pilot area Linköping.
Fig 2. Location of sampled and with drones mapped outcrops and survey lines for the VLF and magnetometer measurements.
Fig 3. Example of dronar image of on of the outcrops and interpreted fractures and main fracture orientation for all the mapped outcrops.
Fig. 4. Illustration of the revised local bedrock map (left) and a conceptual map of the thermal conductivity based on the magnetic susceptibility, bedrock map and thermal conductivity measurements on outcrops (right).

Find out more about the pilot area Linköping in our previous blog: Pilot area activities – #2 Geological and geophysical surveys in Linköping, Sweden

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