Infrastructure 101: Flywheel UPS
It’s no secret at Data Cave that our critical UPS infrastructure is built from flywheel UPS units. Our initial build consists of multiple Active Power based CS1200Z units providing the critical power needs to the customer and internal IT loads.
Conceptually, the system works almost exactly the same as battery based systems that people are familiar with. However, the difference is in the energy storage. With batteries, energy is stored in the batteries and is released as part of a chemical reaction. With flywheels, the energy is stored as kinetic energy, with large rotating steel disks. During normal operation, electricity is used to power the flywheels or batteries and keep them steadily “charged”. When the source power goes away, as in a power outage, that stored energy is then converted to electrical power to keep the critical load powered until a backup source, such as a generator, can be brought online.
Flywheels: still a great choice for data centers
Even though flywheel technology is older, it’s still sometimes viewed as the new kid on the block for data center UPS infrastructure – while batteries are the incumbent. This very fact alone causes many new data center build designs to prefer batteries over flywheel systems. However, in just the past two years we now see that there are a number of flywheel manufacturers, and all leading battery UPS manufacturers also offer flywheel options to their product lines. This evidences the demand.
The choice of flywheels is compelling. The systems are significantly smaller than their battery counterparts, as they don’t require the large amount of space taken up by batteries. They’re also more environmentally friendly, as the batteries don’t need to be replaced each year, and the chemicals inside of them are considered non-environmentally friendly. And, usually, the overall electrical efficiency of the units is higher than equivalent battery systems (97% vs 92% is what we’ve found). While a 5% difference in efficiency looks small, it is quite significant when you’re talking about megawatts.
Of course, the main downside of the units is their significantly reduced runtime next to battery systems – seconds vs. minutes. Depending on the design and load, a flywheel system may only provide 30 seconds of operational runtime vs. upwards of 15 minutes with battery systems. This is significant. However, in our experience is makes no difference. Our 2 megawatt generators are designed (and tested) to be up and online within 20 seconds – and we routinely see 12 seconds as the normal startup time. We simply don’t need 15 minutes to switch to generator power.
In short: we love our flywheel systems, and feel very confident about their ability to perform their critical operations.
We also love giving tours. Contact us today and we’ll happy show off our flywheel systems, and all of the other critical systems that make our data center one of the best in the midwest.
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