Using Flywheels to Meet Peak Power Grid Demands

hackertourist writes "A novel type of electricity storage was recently added to the New York power grid. The unit, supplied by Beacon Power, uses flywheels to store energy. This system is intended to replace gas turbines in supplying short-term peaks in power demand (also known as frequency regulation). It can supply up to 20 MW, using 200 flywheels." If you can't afford a 200-flywheel system, you can always get a racetrack-ready Porsche 911 GT3 R Hybrid, which has a single energy-storage flywheel that can give you a 160 HP burst of power when you need a little extra oomph.

Comments

Re:and if you use maglev bearings

[gblackwo]

The discs do appear to be parallel to the ground so keep in mind that depending on which way they are spinning and which hemisphere they are in, the Coriolis effect will either help or hurt them.

Gimbals

[TomorrowPlusX]

Dumb question, I suppose. But, given that the earth rotates, and given that the flywheels will have a huge angular momentum, are they gimbaled? The article says they're suspended in a vacuum, levitated on a magnetic field, which is cool. But if they're not gimbaled a huge amount of energy will be wasted fighting precession as the earth rotates.

I assume the people making these things are smart and know their shit. I'm just curious how a problem like this is solved. If not gimbals, what?

Re:Gimbals

[SETIGuy]

But if they're not gimbaled a huge amount of energy will be wasted fighting precession as the earth rotates.

You don't need to gimbal them. If oriented correctly you can draw energy from the rotation of the earth to fight the precession effects. Basically nearly all of the force that keeps the axis aligned is transmitted through the mounting, and only tiny amounts will be derived from the rotation. Induced currents will be a more significant source of losses.

What's the cost?

[jamesl]

Why don't these alternative energy/power storage articles ever include cost comparisons? What do these flywheels cost to buy and operate compared to what they're replacing?

Re:What's the cost?

[h4rr4r]

but they don't see that the CO2 output of building the damn thing divided by its useful lifetime is much higher than a heavy polluter coal plant that lasts much longer and is easy as hell to build.

It's not. Please let us know why you think it is.

Re:What's the cost?

[h4rr4r]

It depends on what system you're looking at. Old solar panel technology took a large amount of nasty chemical pollutants to make, and produced a hell of a lot of liquid toxic waste output. I think our solution has been to dump it in the water supply.

That has nothing to do with co2. All commercially available solar panels have had payback times in co2 terms of less than 50% of their lifetimes.

It's like buying a fleet of electric or hybrid cars for their "environmental impact," while Toyota won't release statistics on how much energy goes into building one and how much pollution it produces. There's no total lifetime numbers for something as innocuous as CO2, which leads many to speculate that Toyota might keep such things secret because the total CO2 production for an electric hybrid exceeds the total CO2 production for a 25mpg Sedan over its expected lifetime. Less not knowing, and more not caring because the numbers in front of you support your foregone conclusions already.

You can figure out how much energy goes into making one, look at the price. A 25mpg sedan is going to probably cost more than a prius anyway, as it only gets 25mpg for a good reason. That is because it is heavy and made from more material generating more CO2 when it was produced.

A corolla might be better over the lifetime of the car in co2 terms vs a prius, but that 25mpg sedan won't. An electric car in fleet use might be even better, depends on source of that power.

Your talking points suck. Stop moving the goalposts and do some fucking math.

Re:What's the cost?

[k8to]

Looking at the price for CO2 cost is a lot more accurate than some might think. There's some research which shows that costs closely track energy used in production, and that in turn should closely track CO2.

Sure, some things deviate, like the priciest wine vs the cheapest, but for things like pens, cars, computers, where pricing pressure exists (even for most luxury cars!) it seems to mostly hold.

Re:New tech?

[plut4rch]

The JET tokamak has had a couple of huge flywheels to provide the power to its field coils since the early 1980s, and those are around 400MW peak output. True the pulse only lasts around half a minute or so, but it's still very impressive. Each flywheel has a moment of intertia of something around 14 million kgm^2. This may not even be that relevant to TFA but I thought it might be interesting.

Re:Power should cost more during day time.

[h4rr4r]

Domestic electricity prices are constant all day.

Maybe where you live, but not where I live. I bet if you requested the time based pricing you could get it. When I was growing up we only did laundry and dishes after 8pm. Cut the electric bill by a huge amount.

Re::-) but a serious question, what % loss?

[Gibbs-Duhem]

The efficiency of an electric motor can be in excess of 90%. Energy is transferred to a flywheel via electric motor, and extracted (mostly likely) through the same electric motor, so your maximum theoretical efficiency is going to be your motor efficiency squared. If they tried hard, probably something like (92%)^2 or something like 85% total storage efficiency.

This is of course assuming that mechanical losses are zero, but given the design they are very likely to be close to perfect. There will also of course be some energy lost indirectly in levitation/cooling/ohmic stuff outside of the flywheel.

I think the thing about this article that bugs me the most is they say that the flywheels can store 20MW. What on earth kind of way to measure an energy storage device is that? 20MW for 0.5 seconds? 20MW for three days? Embarrassing.

Re:New tech?

[TheRaven64]

One of my physics teachers at school used to work in a power station for a bit. He showed us some pictures of a 'fuse' that they used. When I think of a fuse, I think of a small, thin, piece of wire. This was a large copper bar. He also had some pictures from when it blew - the entire bar was vaporised. When people talk about MWs and GWs, the numbers don't seem real. When you see lumps of copper being instantly turned to gas, you get a real feeling for the amount of power involved.

So, in monetary terms...

[alispguru]

... the system can buffer $500 worth of power (5 MWh = 5000 KWh, $0.10/KWh wholesale).

And it cost $40 million to build (at least that's the size of the loan)? That's 40,000 times the value of the energy it can hold.

If the buffering keeps an expensive peaking source off-line, it might pay for itself in a few years of continuous use.

Re:New tech?

[goodmanj]

My worry isn't rolling stones, it's shrapnel. Beacon Power's flywheels store 25 kwh of electrical energy. If the rotor fails, this energy will be released in a fraction of a second, causing an explosion with the same energy as 20 kg of TNT. But TNT releases most of its energy in the form of heat, which is imperfectly converted to kinetic energy, while the flywheels will release pure kinetic energy. And it's kinetic energy that kills people. You'd better hope the engineer who designed the metal casing for the flywheel knew what he was doing!

Re:New tech?

[Gibbs-Duhem]

If memory serves, the giant flywheel that MIT uses to spark their fusion test reactor is rigged with explosive charges to blow it to pieces if it ever came loose. I believe the calculations show that without detonating it, it would likely continue *through* several buildings before landing in the Charles River... could have been an urban legend though.