Utility scale flywheel systems are being added to new powerplants, but it's been slow going. Utilities are not exactly dynamic organizations; my cofounder used to consult for one, getting them to change anything was an enormous pain. There are many growing companies in this area: Beacon Power is one in particular.
They aren't being added to nuclear powerplants because nuclear powerplants have a wide and controllable dynamic range (they can run higher or lower depending) and new ones aren't being created.
There are large scale installations of flywheel systems in government use, though. The Princeton Plasma Physics Lab used a flywheel system for peak power delivery, as did many other government labs; including particle accelerators.
Utility scale flywheel systems are being added to new powerplants
Can you name one?
Beacon Power
Has Beacon Power ever made a single sale in its 11-year existence? I see it is trading at $1.25 (up from 84 cents, within the last year). The NASDAQ keeps threatening to delist it.
On making sales, the short answer is yes: they announced a sale as far back as 2001, uncovered from shallow googling. This was for a telecom utility though, not a powerplant scale utility.
[edit: in H1 2007 they produced sales of $842,034, with $30,244 gross profit, minus substantial operating expenses of $6,443,344. Such magnitudes may or maybe not be expected in a startup company]
On adding to powerplants, the intent with the beacon power demonstration plant is to actually commercially deploy the system and make revenues from regulation services. Technically this is not adding to an existing powerplant, though it is adding to the power grid. Eventually the aim to to add to existing power plants where possible, as this avoids transmission losses.
I'm not intimately familiar with the state of the two large utility scale demonstrations. The public information, posted in their stockholders 'results' release, is that they're building a 5 MW plant, have tested a 1 MW system, siting another (10 MW), and ramping up to production; following approval in open bid regulation market.
Beacon expects to have frequency regulation facilities in two locations before the end of 2008 with a total of five megawatts of capacity. To that end, the Company has initiated the process of establishing up to five megawatts of frequency regulation capacity on its Tyngsboro site, and is actively pursuing potential locations in the PJM Interconnection in addition to a site in Stephentown, New York. On July 17, 2008, the Company received a land-use permit it had requested from the town of Stephentown, New York, and subsequently exercised its option to purchase the land. Pending approval of an active interconnection request to NYISO and any other implementation requirements of the NYISO, a possible location for Beacon's first 20 megawatt frequency regulation plant will be in Stephentown.
There's also Pentadyne, which manufactures smaller scale UPS systems, used, for example, in process plants. The economics are much the same though, since it competes against batteries. If anything, economies of scale should tweak toward the utility scale implementation.
Actually, I don't think so. The accuracy of one's predictions must be weighed against the expected importance of their consequences on how one might decide to act. Obviously this is an issue important to both of us. But the energy problem is a big problem, perhaps the problem, with monstrous amounts of data, being generated faster than one can argue about it, at detail.
The goal is to act well, not to make zero mistakes. The arguments we've had have unearthed interesting data, but I would not suggest it's worthwhile to continue much further, unless, for either of us, it is in good sense productive. Some of the arguments and contrary positions you've taken have been very helpful for me. But I must admit, I am getting tired, and there is work to do.
They aren't being added to nuclear powerplants because nuclear powerplants have a wide and controllable dynamic range (they can run higher or lower depending)
Nuclear powerplants, typically, are capital intensive. For this reason, their operators aim for high capacity-factors. Unless economic forces are being ignored, they cannot easily be throttled. They run at 100%, all of the time, except when they are being refueled. The only nation that uses its nuclear powerplants in load-following mode is France -- since such a high proportion, some 80%, of its electricity is nuclear -- and France pays a price for that.
Additionally, it is not mechanically good for a nuclear-powerplant to throttle up and down. Such cycling causes parts to wear-out faster. If it is going to be used at all, it is best to keep it on, at a steady output.
There are other considerations. The nature of reactor poison build-up is such that throttling-up immediately after throttling-down tends, in typical reactor designs, to be difficult to do.
Unlike nuclear-powerplants, hydro and gas-turbine powerplants load-follow well (though the more-efficient gas-turbine powerplants take longer to start-up and might have to burn fuel, idling).
I will confess I know less about fission power plants than you seem to. Good point on the capital intensity. I suppose this does answer why there aren't major flywheel installations are not present at nuclear powerplants.
One thought: why aren't there flywheel systems at wind turbines, moderated by a CVT? This would get rid of a lot of transformation losses, and since a motor is unneeded it would be fairly cheap.
There are two methods to throttle nuclear plants: by control rods, moderating neutron flux, and by temperature, moderating coolant flow (in, say, a pebble bed reactor). Either of these work well for generating heat, though coolant flow is simpler technically. Beyond this the plant is a steam turbine, which would have the same maintenance problems as any other steam turbine designed for the load. It's not as fast as gas, but the fuel is cheaper. But as DabAsteroid pointed out, Nuclear Plant are typically base loaded, in the US at least, so that's not terribly relevant.
I don't understand enough of the specifics of the particular designs Dab alludes to to comment on reactor poison buildup. I know that in pebble bed reactors throttling was intended by design.
I think that within the US market (which was, erroneously on my behalf, what I assumed the conversation was about), the point of new power plants not being yet created still holds: whatever load balancing one would need is an investment already made. (though this is mostly irrelevant to the point of discussion where nuclear plants don't supply peak demand). Of the proposals for which nuclear plants would supply peak power, the question is still out there: how will they balance the load? There are many possibilities, but they're mostly guesses. There is, increasingly, a diverse market for load balancing technology, and companies, struggling with technology and sales and tradition and economy, to try fill that need.
There are also resistive shunts that can be used in conjunction with an entire national 100%-nuclear fleet running at full throttle full-time. The resistive shunts would be used to simply dump any excess power. We use resistive shunts for this, today (which is how we get rid of wind and solar power that grid utilities are required to "buy" from the public), but in the proposed scenario, they would be used even more. To encourage demand during times of excess supply, a real-time free-market could help.
I envision that demand fluctuations would be smaller in the future, because of larger overall demand dwarfing weather/seasonal/earthspin-related (paganistic) heating and cooling fluctuations, and because of a global move toward a continuous day (after all, many of us are up in the "middle of the night", here, making our "day" when we feel like it).
http://beaconpower.com/
They aren't being added to nuclear powerplants because nuclear powerplants have a wide and controllable dynamic range (they can run higher or lower depending) and new ones aren't being created.
There are large scale installations of flywheel systems in government use, though. The Princeton Plasma Physics Lab used a flywheel system for peak power delivery, as did many other government labs; including particle accelerators.