HOMER Energy Support

Modeling flywheels

Last Updated: Apr 04, 2018 02:40PM MDT

Do you have plans to add a flywheel storage option to HOMER?


Yes we do have two types of flywheel models in HOMER Pro: 

1) Reserve Model/Flywheel model
2) Idealized storage model

The reserve model, as the name suggests, provides operating reserve capacity to the system. It also needs a constant Parasitic load to operate.

The idealized storage model is an AC device, but HOMER will connect it to the DC bus because it cannot model AC electrical storage.  To model this flywheel in HOMER, you should add a converter, but make it free, 100% efficient, and larger than the aggregate capacity of the largest number of flywheels that you are considering.

Some of the relevant properties of both the flywheel models are:

1. Long cycle life (they can be charged and discharged many times without


2. Lifetime throughput is independent of cycle depth.

3. High round-trip efficiency

4. Rapid charge and discharge rates (high kW rating)

5. Low energy storage capacity (low kWh rating)

6. Rapid self-discharge (relative to batteries)

7. High capital cost


HOMER's battery model can model all of those properties except number 6.  HOMER does not model self-discharge, and in some situations that might be an important aspect of the flywheel's performance.

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