energy cache gravel trolley

ws9876

Have you seen this system that uses solar power in the day to push buckets of gravel up a hill and dump them and then somehow at night runs the gravel downhill
to turn a generator. Its by a company called Energy Cache. I wonder if they direct drive a generator from the big sprockets at the bottom??
It is supposed to be much cheaper than hydro storage and less EPA problems.And gravel is super cheap.