Not sure why.
Only know that it takes hours/days to get boilers up to steam pressure to take over as the wind dies, or clouds cover the sun.
I guess it works for your home, as you’re always plugged in for backup, or an expensive battery pack can provide for your own needs. But the battery backup doesn’t scale up.
Thanks for the info. If private industry wants to go for it, that’s great.
Just not govt funds. Solyndra or whatever it was called, was enough.