Design and Scaling Laws of a 40-MW-class Electric Power Distribution System for Liquid-H-2 Fuel-Cell Propulsion

Electric propulsion is understood to have many advantages for commercial aviation, including 2-6x reduced fuel costs, similar to 3x lower purchase cost, > 10x reduced maintenance costs, large reduction of CO2 emissions, and other. Transportation is a leading source of greenhouse CO2 gas emissions, with aircraft contributing to 10% of the CO2 emissions equal to 900 million metric tons. The use of green H-2 gas/liquid produced with renewable energies, could result in zero CO2 emissions. Implementation of all-electric, hybrid, and turboelectric propulsion systems presents many difficult challenges in regards to power capability, specific power, and specific energy. Superconducting power transmission and cryogenic machines have unique properties that can help overcome these challenges. Advantages include no ohmic losses, and utilizing ultra-small/light conductors which can enable practical solutions for lower transmission and system voltages. Cryogenic machines utilizing superconducting wire have very high efficiency typically > 99.9% including cryo-cooling losses, and can operate at ultrahigh current densities > 1000 A/mm(2). This presentation provides the design and scaling of an electric power distribution system for 40-MW-class power, and compares different wire technologies including cryogenic metals, superconductors, and 'conventional' metals at ambient temperatures. To effectively study how to optimize the weight and efficiency of electric aircraft designs, the mass and heat loss scaling laws of the components of the electric drivetrain are required for varying power/voltage /ampacity levels (0-20 kA) and power-wire distribution architectures, which is a focus of this work. Electric power system components studied thus far include metal conductors (Cu-clad-Al (CCA), Al 99.999% 'hyperconductor'), busbars, current leads, metal/superconducting T-joints, high temperature superconducting (HTS) Y,RE-Ba-Cu-O cables, and cryoflex tubing. A weight and efficiency analysis of a 40 MW power drivetrain system will be provided, and material options for the power transmission cable will be compared.