Battery plus flywheel to mimic grid fault advantage of pumped hydro?

Discussion in 'General' started by 101101, Mar 9, 2018.

To remove this ad click here.

  1. 101101

    101101 Well-Known Member

    Batteries are going to be critical to the clean grid that will support a no nonsense 100% clean grid (non carbon sequestered generation) but the current claim in the US is that 1300 GWs or 15x current current pumped hydroelectric storage will be needed as part of the grid back up at about 1.5 million dollars per mwh of virgin capacity where per Jacobson this can be had by upgrading generators at current sites. But Jacobson aims really low with full replacement of fossil fuels and nuclear 33 years from now. On the other hand for the US it would be a mere 1.5T dollars even with virgin capacity to reach the pumped hydro component goal. That's not even a years worth of direct state global petrol subsidies.

    It seems the issue is that batteries have a problem with grid fault back up but can cover just about all other scenarios. I suppose that is the extreme situation where a whole section of grid goes down and needs to be kept from deflating but lesser versions of grid fault are also taxing. It also turns out that pumped hydro, limited as it can be is pretty flawless all around. Could pump sea water up hill?

    My question is why can't batteries plus flywheels mimic the advantage of hydro for grid fault. Gas plants do this by their wasteful default, they keep a flywheel spun up all night long. So in this case it's almost like regenerative braking in an electric vehicle. At first its sounds inefficient i.g., conversion from electrical to chemical to mechanical back to electrical. I am guessing the issue is pumped hydro with its massive heavy impeller (quick spool fly wheel effect) gets an instant impulse and also that its mechanical generation provides for massive voltage like Van De Graff voltage generation but also massive amperage so it can fill an inductive void- really rusty on this stuff.

    Clearly if it were so obvious the people who develop this would already be doing it. What's wrong with this type of logic. Have to also say I get that they want to diversify with hydro, and it sounds cool sun, wind and water.
  2. To remove this ad click here.

  3. marshallwa

    marshallwa New Member

    PBS run a show (NOVA) on energy storage. It featured one company that was working on flywheel storage. You might see if you can still find it.
  4. Roy_H

    Roy_H Active Member

    There has been a lot of research and several companies building and selling flywheel backup systems for electric utility companies. But I have not heard anything announced for the last several years except battery backup being installed. Either flywheel backup just doesn't get publicity, or batteries have proved to be the better value from electric utilities viewpoint.
    101101 likes this.
  5. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    Flywheel storage was briefly covered in the "Nova" episode "Search for the Super Battery", which featured host David Pogue.

    Quoting from "Booting Up the Search for Better Batteries":

    For now, at least, no one battery can do everything we want batteries to do, but Pogue’s travels indicate the research field is booming. “Some of the coolest things we looked at were ice batteries and gravity batteries and flywheel batteries and saltwater batteries and dirt batteries,” he says. “It’s just billions of dollars are being poured into this, in research labs all over the world.”
    But flywheels simply are not practical for large-scale energy storage. What's the problem? If I recall correctly, the basic problem is that even when great efforts are spent on making their bearings frictionless, they still run down and lose all the stored energy within a few hours. As I recall, flywheels are used for stationary energy storage most often as a UPS (Uninterruptable Power Supply) for large buildings, such as hospitals, where maintaining electrical power is critical. But they provide power for only a few minutes, giving time for emergency generators to be brought online.

    As far as large-scale energy storage systems explored in that "Nova" episode, I'm most interested in what Pogue is calling "dirt batteries", which are batteries made from materials which are quite literally as cheap as dirt. The energy density is abysmal, but for large-scale grid storage, that is not a very important downside. Even if the storage sites each have to be as big as a small mountain, that still would be much more practical than a lot of the other proposals.
    Last edited: Mar 9, 2018
  6. NeilBlanchard

    NeilBlanchard Active Member

    Flow batteries are good for grid and home storage.
  7. To remove this ad click here.

  8. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    Flow batteries are certainly an interesting tech. I've been hoping researchers will solve the problem of limited power from flow batteries, but after some decades of waiting I've pretty much given up hope. They can increase the storage capacity easily, just by scaling up the tanks holding the electrolyte, but increasing the power significantly has eluded them despite some decades, now, of R&D.

    I don't know enough about "dirt batteries" to know if they would have a similar problem, but I'm hoping not!
  9. 101101

    101101 Well-Known Member

    I personally don't like the idea of fly wheels but I've been thinking that having some energy from a system in a pres-spooled up fly wheel might be able to address just the grid fault weakness of present Lithium Ion battery systems. It seems I don't get why hydrologic water flow through a turbine can't be emulated for that effect with a reciprocating mass. You can easily imagine that a battery bank could pump a bunch of water up hill so it must just be the moving heft of the hydro pump impellers acting as fly wheels that is the difference. And if this difference can be accounted for in this way on grid faults we can bypass the criticisms of Jacobson's 100% renewable approach which is critical.

    The fossil fuel/energy industry has to understand that its over that there is no place for its crap- and justice demands that there be none with retributive economic consequence. The usual argument that public investors are entitled to a return is crap here- it should have just been taxed away to begin with and in essence it is being taxed away- there was no room for profit in these private monopolies Coase was stupid relative to Hotelling on this . Just because it was a public investment doesn't mean they had a right to risk-less on return. The continued investments in petrol are criminal and stupid beyond belief- if it were me petrol investors would face criminal prosecution sooner because its worse than investing in the regular black market.
  10. Martin Williams

    Martin Williams Active Member

    Interesting that flow batteries in cars seem to be acceptable where hydrogen isn't. The two are rather similar in that reagents are combined so as to generate electrical power. The big differences are that in a flow battery the reagents are liquid and therefore heavy, two are involved, and they have to be returned after use. Hydrogen requires a high-pressure tank, but only one light reagent needs to be supplied (the other comes from the air)and the result can be safely discharged to the environment.

    I submit one idea which may or may not be practical, and that is to use a flow battery as a way of getting a lot of power into a battery car quickly. The filling station provides the reagents which are fed into the car where they are converted into electrical power to charge the battery. I haven't looked at the detail or sniffed for the smell of sulphur. The bulk of the thing would obviously be one problem. The power conversion level would be another. To get 100kWh into a car in 2 minutes (say) involves 3MW which is prohibitively dangerous in electrical form. Doing it with a flow-battery might turn out to be as safe as filling the tank on a conventional car.

    Not to be taken TOO seriously at this point. I am rather busy with other things now but will try to research the feasibility when I get time.
  11. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    So far as I know, nobody is using flow batteries in automobiles. Please note this discussion thread is about grid power storage.

    I do vaguely seem to recall seeing one single InsideEVs News article about some sort of concept car or prototype car which was claimed to run on flow batteries, but it seemed to me to be very sketchy, and probably just another example of how many or most claims from high-tech battery startup companies are outright B.S.

    I have seen at least one proposal for EV filling stations to replace the electrolyte in batteries with freshly charged electrolyte. While that is very probably possible in the engineering sense, I have not seen anyone demonstrate that it can be made practical in the economic sense. Adding liquid fuel to a fuel tank is quite simple, so long as that fuel is liquid at room temperature and pressure. Even low-pressure gas (such as propane or LNG) isn't that big of a problem to dispense. (One of the tractors on my grandpa's farm was propane powered, and filling up the tank didn't take much longer than filling up a diesel tractor's fuel tank.)

    But back to replacing the electrolyte in an EV: The problem, it seems to me, is with removing the old, spent electrolyte from the battery (or batteries) before -- or simultaneous with -- injecting the fresh electrolyte. I have yet to see anyone demonstrate how that could be accomplished with a system which would be simple and fast enough for practical use at a filling station.
  12. To remove this ad click here.

  13. Martin Williams

    Martin Williams Active Member

    My suggestion was not to do away with battery-powered cars, but to use flow battery technology to power the usual batteries, using charged electrolyte supplied by the filling station to an onboard flow battery which would safely charge the conventional batteries. (Back-to-back flow batteries are used as high powered DC-DC converters already in some applications.) The car would carry NO electrolyte in use and would run on batteries as they do now.

    The idea was to be able to get a lot of energy into the vehicle quickly, without resorting to ridiculously high voltages. It depends on a high power flow battery (3MW maybe) being small enough to mount in a car without bending the axles, and of course batteries which can be fully charged in two minutes. Both seem extremely unlikely in the near future, if ever. So it probably isn't very practical.

    A pity, as it would make for safe recharging in a time comparable to tank-filling, but you can't have everything. I'll look into it more carefully when I have time.
  14. 101101

    101101 Well-Known Member

    There is the metal fuel or dry metal fuel approach that I think IBM was working on for very quick reliable power transfer. But
    I don't think its dangerous certainly not more dangerous that gas transfer. Tesla Mega Charger is an example. These are DC circuits.
    It would be 3 mega charger lines going into the car. If you wanted to make it work the car would pull up and these would engage underneath the car automatically. But honestly a mega charger would charge a 100KWH batter to full in 6 minutes. That is about as fast a gas and its safe.
  15. 101101

    101101 Well-Known Member

    I am going to answer my own question because I've had some time to think about out. There is nothing that stops batteries from replacing pumped hydro right now.

    Logic is follows.

    1. A bank of batteries, at night for instance, would keep a heavy fly wheel (pumped hydro heavy impeller) spun up.

    2. In a grid fault the instant need for energy would hit that rotation of that fly wheel as generator on one side of it began produce power and
    and create drag.

    3. Simultaneously an electric motor on the other side would begin to add back in spin force to counter the drag.

    It seems that what conventional batteries lack something akin to the conventional transmissions clutch- a load matching and balancing system that is up to the demand or strain that a fault would place on the system. The heavy load and its inertia in this system provide the coupling and balancing element.

    That this is possible its quite evident in that batteries could be used to power pumped hydro up hill in the day and the pumped hydro could be let to flow at might to let the system recharge with equal rates.

    Real issue for a battery must just be the instantaneous load that a fault response requires but the battery based system above with a fly wheel used as a coupler only provides a means to emulate pumped hydro's main advantage. P

    Pumped hydro has some other advantages but it also has many disadvantages.
  16. Martin Williams

    Martin Williams Active Member

    Put some figures on your ideas. Otherwise, they remain pipe dreams.
  17. Martin Williams

    Martin Williams Active Member

    AC or DC makes no difference to the power levels required. 100kw in 6 minutes is a MegaWatt for six minutes. I don't believe that's safe. It is also three times longer than a tank fill, long enough to be irritating. And are there batteries available that can be fully charged in 6 minutes anyway?
  18. 101101

    101101 Well-Known Member

    Yes, faster as a matter of fact. Look at Store dots quantum dot tech. Also you can look at the graphene stuff that Fisker keeps going on about. And no, nothing irritating about it when you consider most charge couplings will likely be mostly wireless unobtrusive, available seamlessly in may parking lots and parking spots, more importantly that same tech in home garages mean most electrics never come to service stations and most of all the predicted 18x reduction in vehicles on the road due to autonomy. Finally the real consideration that people will likely not fill all the way up at the service station because its likely to be cheaper at home and the autonomy system maximize the safety margin on range while minimizing cost and waiting. People will be able to add an emission free, much cheaper and reliable 100 miles in the time it would take to put dirty petrol in the car. All of these things will hit people like a revelation and there will be not petrol counter.
    Last edited: Mar 11, 2018
  19. 101101

    101101 Well-Known Member

    Sorry not, thought experiments are stronger that people just throwing out numbers of damn lies in the form of statistics with circular circle jerk citations. Thought experiment there unless someone counters it is strong enough to say its possible, but we can see distributed micro grid use of batteries obviates the need for pumped hydro in any form.
  20. Martin Williams

    Martin Williams Active Member

    You can, no doubt, construct a DC charging system that is faster than an AC on. You can also just as easily construct an AC charging system that is faster than a DC one. It's simply a matter of where the rectification to DC is done. In the charging station or in the car. There is no particular speed advantage in either.

    As to charging a battery pack in six minutes flat, I will believe it when I see it. No doubt someone claims to do it in laboratory conditions, but in a practical battery pack for a car, capable of lasting many years over a wide temperature range and with reasonable energy density it is probably years away if not decades.
  21. Roy_H

    Roy_H Active Member

    Pumping a million tons of water uphill into a large lake is perfectly reasonable, now can you imagine a million ton reciprocating mass? Definitely not feasible.
  22. Roy_H

    Roy_H Active Member

    I'm sorry 101101, but you just lost all my respect for you. Are you high on drugs? Your post makes no sense whatsoever, am I to assume that the pumped hydro impeller is not in water but running dry? This would be a relatively small amount of energy. Any scheme where you draw energy from a generator and then make up lost power by adding an electric motor is nonsense. All you have done is throw away some heat energy losses and gained nothing.
  23. 101101

    101101 Well-Known Member

    If you read the above you would know that was anticipated. But its not like the million tons of water is immediately active on that impeller, its some tiny fraction acting on a set of impellers to include the substantial weight of the water column. And if a set of batteries could pump the water up hill in the first place it must just be something about the immediate moment on the heavy impeller- in practice such impellers may already be in motion in hydro.

    I am saying this situation could be mimicked by having a pool of inertial energy on tap in a flywheel for the initial sharp rise in load from and then feed the expended energy with with batteries. But there is no need for this inelegant electrical to chemical to mechanical to electrical situation because supplementation of the grid with micro grid battery back ups knocks the problem down enough that batteries alone can handle it.

    "Any scheme where you draw energy from a generator and then make up lost power by adding an electric motor" What? This was a thought experiment and it didn't entail that. Spool the flywheel anyway you want (I get that it doesn't have the load of the water column behind it) including daytime PV. After it absorbs the jolt run it on battery as needed while tapering to straight battery. This isn't something I claim to have any solid grasp on (note above where I said if this were possible the pros would have done it...) but in a catastrophic fault my guess is the grid and its inductive load is like a balloon that is deflating and something has to pump it back up again- might almost be like trying to reverse a rushing river. The water in the column comes rushing down like a hammer.

    Now lets blow up the BS you were trying to push above: If natural gas and diesel generator engines are used as fault back up then you know its BS that batteries can't handle grid fault even if they had to run an electric motor to drive an electric generator- literal BS- that's all the reciprocating ICE engines are doing. And that battery to motor to generator arrangement (possibly aided by fly wheel sump/clutch mechanism) was the inelegant bit I was attempting suggest above as thought experiment. But even aside from this and aside from the better micro grid solution now that I see their actual response is distribute diesel generators I can see its nothing but petrol ICE BS as usual trying to say batteries couldn't be used to handle the load. The kinds of motors power these generators as in locomotives or small ships. But again it doesn't seem like anything batteries couldn't do alone in micro grid or with some kind of power conditioning arrangement that would probably just boil down to more batteries but would be unnecessary due to supplementation with microgrids as back ups or even primary where the grid is the back up.

Share This Page