Solar thermal can melt salts turning the salt liquid at 600 degrees. I've read that there is alot of waste converting elec to heat and vice versa. However if it is waste electricity that was only going to be dumped then it's a moot point. Storing the heat would be very useful.
Discussion
Yeah, but solar thermal does that with arrays of mirrors as big as a solar farm that have to be actively focused to concentrate the heat.
They even mention that their energy density per land area is lower than other forms of actively capturing solar energy, but that the extremely reduced cost of install and maintenance for a static farm (fixed panels at low angles for reduced wind shear) are what make it possible for the long term economics of this project to compete with natgas
Now.... I wonder if there is a similar passive way of capturing solar thermal on a comparable land area that can reach 800C or whatever