Flywheel Energy Storage System

The goal of this project is to design a flywheel energy storage system (FES) for a potential lunar mission to be conducted by NASA.

Background
One of the problems a potential lunar mission faces is energy generation and storage. While both solar and nuclear power generation are options, they do have drawbacks. Generating electricity using solar power would not be possible during the approximately 14-day lunar night, and nuclear power generation would have to decrease during the lunar day due to heat. As a result of these drawbacks, an efficient method of storing energy would be needed to ensure the success of any planned lunar mission. The University of Idaho has put forward the idea of using a FES system (FESS) to accomplish this. FES is advantageous due to its high energy density and long lifespan compared to other methods of energy storage.

Passive Magnetic Bearing
The passive magnetic bearing is responsible for levitating the flywheel by utilizing liquid nitrogen-cooled superconductors combined with powerful permanent magnets arranged in a Halbach array. The Halbach array was particularly useful in this implementation, as it augmented the magnetic field below it while greatly reducing the magnetic field above it, thus improving levitation while reducing interference with the magnetic fields in the stator.

Active Magnetic Bearing (AMB)
The UIFESS utilizes two AMB's to both power the flywheel and maintain a 1 mm air gap between the rotor and stator components of the FESS. These AMB's are located at the top and bottom of the stator, with the top AMB acting as a stabilization bearing (SB) and the bottom AMB acting as a self-bearing machine. The AMB's allow the flywheel to rotate at a theoretically unlimited speed and increase the efficiency of the FESS, as there is no physical connection between the bearings and flywheel.

Stabilization Bearing
The top bearing purely acts to provide corrective forces to the flywheel in order to maintain a 1 mm air gap.This 8 pole dedicated AMB was added to the original UIFESS design in order to create restoring moments on the rotor.

Self-Bearing Machine (SLFBM)
The SLFBM portion of the FESS reduces the hardware complexity of the system as well as the mass and size by removing the need for a dedicated AMB. Instead, the SLFBM acts to both rotate and stabilize the flywheel. However, combining these functions into one component increases the complexity of controlling the FESS.

Vacuum Chamber
To eliminate windage losses in the FESS, the entire apparatus is contained within a vacuum chamber. All wiring between the FESS and outside environment thus needed to be run through vacuum couplings in order to preserve the seal and maintain this vacuum.

Team Bios
The 'Fly Rollers' team contributed to this project from Fall 2015 - Spring 2016 and was primarily responsible for wiring the FES system and getting it spinning in a controlled manner. The team consisted of the following members:

Additional Documentation