Biocementation for Soil Thermal Conductivity in HV Cable Zones

The patent replaces mechanical installation methods (embedding thermal conduits or installing complex bedding structures during construction) with a biological-chemical system. Biocementing microorganisms are injected into the soil, which naturally produce calcium carbonate to bind soil particles and create thermally conductive pathways. This biological process substitutes for complex mechanical thermal management installations.

The biocementing microorganisms perform the thermal improvement function autonomously after injection. The microorganisms metabolize nutrients (such as urea and calcium sources) present in the soil or injected with them, producing calcium carbonate that binds soil particles. This self-organizing biological process creates thermal pathways without requiring external control systems or complex installation procedures.

The patent creates a dynamic system where thermal conductivity can be improved at any time by injecting additional biocementing microorganisms. Unlike static pre-installed thermal conduits or bedding materials, the biological system allows for repeated injections to progressively enhance thermal pathways. The soil's thermal properties become dynamically adjustable rather than fixed at construction time.

The method prepares the soil for future thermal improvements by establishing a baseline of biocementing microorganisms that can be activated or enhanced later. Nutrient sources can be pre-positioned in the soil, and the microbial communities can be established in advance, ready to respond to thermal management needs when they arise without requiring major construction interventions.

The patent changes the fundamental parameter of how thermal conductivity is achieved. Instead of importing expensive engineered materials with inherently high thermal conductivity, the method transforms the soil's thermal properties by altering particle bonding through biocementation. The calcium carbonate produced by microorganisms creates contact bridges between soil particles, increasing thermal conductivity through changed particle arrangement and contact quality rather than through high-conductivity materials.

The patent uses inexpensive, readily available substances (urea, calcium sources, and common soil bacteria) to achieve thermal improvement. These materials are far cheaper than engineered thermal bedding materials. The biocementing process uses naturally occurring or easily cultured microorganisms that metabolize cheap nutrient sources to produce the binding agent, replacing expensive permanent thermal materials with a low-cost biological process.

The patent uses injection technology to deliver biocementing microorganisms and nutrients into the soil around operating cables. This hydraulic injection method allows treatment through boreholes or injection points without excavation or cable exposure. The injectable suspension carries the microorganisms directly to the treatment zone, enabling thermal improvement while cables remain in service without mechanical disruption.

The biocementing microorganisms act as intermediaries between the injected nutrients and the soil structure. The microorganisms metabolize the injected nutrients (urea, calcium sources) and transform them into calcium carbonate, which then binds soil particles to create thermal pathways. This biological intermediary enables subsequent treatment without direct mechanical intervention in the soil-cable interface, allowing improvements while cables remain operational.