The story leaves a lot to be desired in terms of defining technology and specifying methods.
Depending on how you buy/sell power, and if you have access to TOU metering, you could spin up flywheels with cheap power and sell it back when rates are higher. If you've got your own generation on site (solar PV, wind, tidal), you could bank excess energy with flywheels.
In terms of storage, flywheel round-trip efficiency is very, very good, above 90% for well-designed systems. The problem has always been storage density and cost. Beacon Power produces 25KWh flywheels priced at around $1000 /Wh.
Add into this the failure modes (Beacon's systems are installed underground in concrete culvert pipe with a several-ton lid cap), and remaining problems with precession (even the Earth's rotation around its axis peturbs flywheels), and they have some significant hurdles. For mobile uses (automobiles, etc.) these problems are compounded.
My money's on large, cheap batteries for grid-scale storage (molten salt or liquid metal), though flywheels for short-cycle load/generation matching may play a role.
Beacon Power produces 25KWh flywheels priced at around $1000 /Wh.
Is that really a $25mil flywheel? Or should that have been $1000/KWh?
For mobile uses (automobiles, etc.) these problems are compounded.
I'm probably demonstrating considerable mechanical naivety with this question, but could you balance multiple flywheels in different directions and orientations to mitigate these problems?
Looks like I had my numbers a bit off. It's $10,000/KWh, putting each flywheel at about a quarter million. The cost data aren't clearly stated and I didn't find my earlier posts on this until just now:
https://plus.google.com/104092656004159577193/posts/21sJzeSw...
Flywheels are used in cars, and the current generation of Formula One hybrids includes flywheel regenerative braking designs. While you can offset gyroscopic effects with counter-rotating flywheels, you still have the issues of loading the bearings of the individual flywheels due to vehicle vibration, movement, rotation, etc. Some of this can be mitigated by gimbal mounts, but that introduces increased volume requirements to the design, and avoiding gimbal lock requires four (rather than three) axes of rotation, one of which must be driven. It's one thing to have the flywheel last for the duration of a race, another for it to stand years of use in a private vehicle.
Depending on how you buy/sell power, and if you have access to TOU metering, you could spin up flywheels with cheap power and sell it back when rates are higher. If you've got your own generation on site (solar PV, wind, tidal), you could bank excess energy with flywheels.
In terms of storage, flywheel round-trip efficiency is very, very good, above 90% for well-designed systems. The problem has always been storage density and cost. Beacon Power produces 25KWh flywheels priced at around $1000 /Wh.
Add into this the failure modes (Beacon's systems are installed underground in concrete culvert pipe with a several-ton lid cap), and remaining problems with precession (even the Earth's rotation around its axis peturbs flywheels), and they have some significant hurdles. For mobile uses (automobiles, etc.) these problems are compounded.
My money's on large, cheap batteries for grid-scale storage (molten salt or liquid metal), though flywheels for short-cycle load/generation matching may play a role.