Pentadyne is trying to make a "Beacon style" flywheel UPS with a composite wheel and magnetic bearings. We have seen how far BCON got with it. Pentadyne hasn't sold a single unit and as far as I can tell from their website, hasn't placed so much as a single beta unit in the field. They want to compete with ACPW but are years behind in development and placement.
The article states that Pentadyne's system can give several minutes of ride through - if true it will be the factor that will beat-out ACPW systems. An average ride through on an ACPW/Cat systems usually generates only 11-15 secs at best on full load. This short ride through period will continue to burden ACPW sales because large data centers need more time just for peace of mind.
As far as weight is concern, who cares if the ACPW systems weighs more---its sitting on a slab and the overall cabinet size is about the same for 120kVA.
Pentadyne will need a lot of good end-user references to move ahead. Untill then facility managers continue to buy batteries----reliable and low cost will continue to out weigh new technology.