In datacenters, the purpose of a flywheel is to bridge from the start of a power outage to generator power being available. In that scenario, you don't need bat

In datacenters, the purpose of a flywheel is to bridge from the start of a power outage to generator power being available. In that scenario, you don't need batteries. If you have batteries, they can come online as fast as a flywheel. This article talks about the issues a bit: http://www.zdnet.com/article/does-flywheel-have-a-future-in-the-datacenter/ http://www.zdnet.com/article/does-flywheel-have-a-future-in-...