The temperatures we’re talking about (1000C) would be incredibly dangerous in residential applications, plus a small installation would lose too much energy to

The temperatures we’re talking about (1000C) would be incredibly dangerous in residential applications, plus a small installation would lose too much energy to the environment due to the ratio of surface area to volume. More practical IMO is to use a daily cycle like what Harvest Thermal is doing: store energy in your water heater tank during the daytime and release it at night.