I can add now that reports are available, one glider pilot in North Wales climbed from 3,000 feet to 23,000 feet. He had obtained special Air Traffic Control clearance..
In my time as an active glider pilot (40 years ago) we didn't need clearance, and several times I climbed to above 25,000 feet (but it can be very cold up there!)
There's a lot of untapped power in the atmosphere. Maybe a different type of turbine needs inventing.
Jack