In addition to being at 600 C, this scheme also crucially revolves around keeping capex as low as possible. Resistive heaters have lower capex than heat pumps.

In addition to being at 600 C, this scheme also crucially revolves around keeping capex as low as possible. Resistive heaters have lower capex than heat pumps. In a system with low numbers of charge/discharge cycles the efficiency drops in importance compared to capex.