ALEGrO Soil Monitoring Approach

Extra-high voltage (EHV) underground cables are an inherent part of the German energy transition. Still, they are controversial among the public, affected farmers, and organizations due to thermal losses and potential effects on surrounding soils and crop yield. This practice uses the 320 kV-DC-Transmission line “ALEGrO” to measure and evaluate the consequence of the EHV underground cable operation to surrounding soils for the first time under real conditions.

Highlights

• Combines a sensor network with an extensive site characterisation and attendant biological field and laboratory surveys concerning earthworm abundance and enzyme activity.
• Combination of weather data with the sensor network enable an innovative description of the site-specific mass and energy balance considering operating EHV underground cables.
• Initial findings that there are no significant impacts on the thermal and energy budget of soils and the microbial activity as well as the carbon cycle in the main root zone.

About the practice

ALEGrO is an approximately 90 km long 320 kV direct current underground transmission line (UTL) from Oberzier, Germany to Lixhe, Belgium. During operation, UTL’s emit thermal energy into soil in relation to electric voltage of the cables and other factors. Soil thermal energy modifies several soil processes directly and indirectly, thus artificial soil warming is a highly significant environmental impact factor. At four different study sites near Aachen, Germany, soil perpendicular to the cable line was monitored. In addition to the continuous monitoring of soil temperature and soil moisture dynamics, at each season of the year soil samples are taken from each soil depth, both within the UTL cable lines and the control sites, to analyse soil microbial properties and metabolic processes, thus soil functioning.