Thermal energy grid storage: Liquid containment and pumping above 2000 °C

•Inert containment of large thermal systems appears feasible and economical.•Graphite foil can be used to seal liquids at 2300 °C.•Metallurgical grade silicon can be contained at 2300 °C.•Low grade pressed graphite can contain silicon at 2300 °C.•Silicon alloys containing 67% iron by mass can be contained at 1700 °C.•Affordable silicon can be pumped above 2000 °C using an all graphite infrastructure.