Lifecycle Analysis of Greenhouse Gas Emissions: Comparing SF₆ and scCO₂ Circuit Breakers

The electricity industry is actively pursuing more sustainable power transmission by phasing out environmentally harmful fluorinated gases (F-gases), particularly sulfur hexafluoride <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\text{SF}_{6})$</tex>. This paper presents a comparative Life Cycle Assessment (LCA) of greenhouse gas (GHG) emissions between <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{SF}_{6}$</tex> and supercritical carbon dioxide <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\text{scCO}_{2})$</tex> circuit breakers (CBs). Specifically, our study evaluates the emission reduction potential of a novel 72 kV <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{scCO}_{2}$</tex> CB prototype developed by our team against traditional <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{SF}_{6}$</tex>-based CBs. We have developed a cradle-to-grave LCA tool tailored for assessing the lifetime emissions of CBs using the GREET database from Argonne National Laboratory. The LCA tool is designed using a process-based methodology, offering flexibility to integrate various assumptions. Results indicate that <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{scCO}_{2}$</tex> CBs substantially reduce lifetime GHG emissions, even under conservative assumptions: Emissions from fluid leakages are reduced by over 99.9%, and total lifetime emissions are decreased by nearly 100 tons CO2e for outdoor installations and over 150 tons CO2e for indoor installations.