Life Cycle Assessment of a Thermal Sprayed Al2O3-NiCr Resistive Heating Coating for Pipe Freeze Protection

In cold climates, precautions must be taken to prevent water from freezing and bursting pipes in aboveground water distribution systems. Conventionally, electric heat tracing cables are installed around pipes to replace the heat lost and prevent liquid from freezing. A multi-layered thermal sprayed coating that includes an electrically insulating alumina layer and a nickel-chromium conductive layer has been applied to carbon steel pipes to provide more efficient and uniform heating. Prospective environmental life cycle assessment (LCA) was used to compare the environmental performance of the two systems with the coating-based heating system modeled based on laboratory-scale production, a laboratory heating test, and conservative assumptions. Under initial assumptions, including a shorter expected life, the coating-based heating system generated more environmental damage during fabrication but used less energy during operation. From a life cycle perspective, the coating-based heating system was found to be environmentally preferable when used in areas with longer, colder winters and where electricity was generated from non-renewable energy sources. Break-even analysis was used to determine the energy efficiency required for the coating-based heating system to be environmentally preferable in different climate regions using different electricity mixes. However, if the coating-based heating system proves to have an expected life similar to the heat tracing cables, it would likely prove to be environmentally preferable in most climate regions. The environmental impact of the coating-based heating system would be further improved by reducing the environmental impact of coating materials production, deposition, recovery, and recycling.