The phase-out of nuclear power in Germany led to a rapid energy transition with a focus on renewables. However, since electricity from renewable energy sources is mainly produced at locations far away from users (e.g. off-shore plants), it has to be transported over long distances. However, the existing grids are not yet designed for this, and so the electricity is "stuck in traffic" and cannot be transported away. Due to the low public acceptance of overhead lines, the 2009 Energy Line Expansion Act (EnLAG) calls for further development of underground cables, e.g. in pilot projects. This development calls for the development of an appropriate bedding material for high-voltage and extra-high-voltage lines that absorbs the high stresses on the soil and the cables caused by thermal emissions and electric and magnetic fields. High thermal resistance of the soil can lead to localized thermal damage (hot spots) of the cable. Thermally conductive bedding allows heat generated by losses to be dissipated from the cable trench and, with less conductor and soil heating, can result in performance increases of up to 21%. Since greater spacing between cables in the ground is not possible due to the larger magnetic field, the bedding material must be able to absorb and dissipate the heat emissions. State-of-the-art bedding materials are lean concretes or sand-gravel mixtures as well as thermally conductive special concretes. However, bedding materials that have high thermal conductivity, can be re-excavated and are durable, and at the same time also increase the performance of the power cables and service life, have not yet been developed Self-compacting backfill construction materials (liquid soils) in accordance with H ZFSV (FGSV) with high thermal conductivity, which are intended to combine all these properties, encase pipes and cables permanently, without voids or stresses, and without mechanical compaction. Compared with conventional backfilling, they require much smaller trench widths and can be walked on after one day and fully loaded after a maximum of one week. By optimizing the aggregate and the binder, liquid soils can be specifically adapted to the given requirements. In this research project, they are to be developed as a thermally conductive bedding material with high conductivities (Fig. 1). In addition to the aspects of sustainability, the increase in performance during current transport and the extension of service life are decisive factors for a practical backfill material.