Episode 43 | Fantastic Flywheels | Amber Kinetics
It was first brought to my attention how flywheels were being used for energy storage earlier this year. It's a very old technology in theory, but recent advances have made them idea for renewable energy storage capable of deploying large amounts of energy, with essentially no degradation over time.
Amber Kinetics is based in the San Francisco Bay area, and has been operating since 2013. The company says it works best charging up and deploying energy (preferably from renewables) to help level out the grid.
Dr. Bill Golove, our guest and Amber's VP of Business Development, spent several years developing wind projects before coming to the company in June '17. He says unlike chemical batteries, flywheels never become less efficient over time. These flywheels are tough, capable of running constantly and requiring maintenance about every 10 years. In fact, if the flywheels were allowed to run the same speed all the time, they could operate for as long as 100 years!
I have to admit I had some challenges getting my head around this technology. My biggest hangup was understanding how flywheels charge up and then deploy energy. Wouldn't the generator slow them down instantly?
After speaking to Amber's Mark Stout for almost another hour, I think I got the process down. Here it goes:
The flywheel consists of a large, steel disc attached bearings that power both a motor and a generator. The system is designed to deliver 8 kilowatt-hours for 4 hours, so 32 kilowatts. The motor, also 8 kilowatts, speeds up the flywheel to 9,000 rpm.
Ideally, the company would love to see this motor powered by renewable energy…wouldn’t we all?
As you’d guess, this Flywheel would start slowing down once power was no longer applied. To combat the friction, the Flywheel has been placed in a vacuum-sealed containment, and magnets lift all but 5% of the weigh the flywheel off it’s bearings. Then a small motor, running at just 100 watts, keeps the flywheel spinning. Kinda of like giving a small push to a spinning plate.
When it’s time for this Flywheel device to create energy, it engages a generator, producing, again, 8 kilowatt-hours of electricity for four hours. During these four hours, the Flywheel gradually slows from 9,000 rpm to 3,000 rpm, the low limit they call the “zero state of charge.”
What’s cool is that though the speed is gradually dropping, there’s no gradual drop in power being created. That’s steady, DC current. The DC current is inverted to AC and the power that was stored in this Flywheel is released onto the grid.
I love that flywheels, and technologies like batteries, vehicle-2-grid and even ice energy storage have formed a cottage industry of energy storage. Not all technologies are industrial-scale chemical batteries, and that is necessary to create large-scale energy storage over the next decade.
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