Saturday, July 18, 2009

Grid Scale Energy Storage Flywheel

There was a major
breakthrough announced this week in grid-scale energy storage. From the news release dated July 13, 2009, "Power Tree Corp. said they have started building a 30 GW energy storage device designed to help implement the smart grid." That is 30,000 MW or roughly the output of 30 nuclear reactors at 1,000 MW each. The amount of power stored per the announcement is somewhat questionable, as it should likely read 30 GW-hrs. If this is a bona fide project, the Grand Game has changed. Wind power can then be stored as much as needed for as long as needed. Same with solar and wave. Nuclear power may be done for; all this depends on the cost of the storage flywheel and how well it actually works.

As I wrote earlier, "The promises that were made in the 1950's by the nuclear power engineers regarding abundant power, that is too cheap to meter, will finally be realized. However, it will not be nuclear power providing that cheap energy, it will be a mix of renewable energy sources coupled to reliable energy storage systems. No matter how cheap uranium is, nor how efficient it is at producing electrical power, nothing is cheaper than free. Wind is free. Sunshine is free. Ocean currents are free. Rain is free. Those are worthy goals for renewable energy, and CO2 has nothing to do with any of it. The engineers are close, and getting closer."

It is quite tempting to state that the day has come, but it is better to wait and see if this super-storage device actually works, and at what price to build and operate.


Roger Vaughan Carr said...

Very interesting, Roger. Similar to the KERS systems used on some F1 race cars and to a lesser extent commercial vehicles, as well as trains.

A far from novel concept, but applied in the power generating industries at the level the linked press release suggests it could have a significant effect... if only to the extent of making the windmill monsters something less than feel-good icons of visual pollution.

Roger Vaughan Carr said...

On going through Power Tree's Energy Storage Technology, Roger, I note this: "...multi-gigawatt storage capacity with hours of continuous megawatt discharge power..."

"Hours" does not sound the timespan needed for wind, wave or sun. "Days" would seem more appropriate as a duration of storage.

Whilst the flywheel device for smoothing would appear to be a very useful step forward on the conventional grid, to claim it for the renewals as anything more than a short-term smoothing is a stretch -- but it sure sounds good... spinning away there... straw into gold...

Roger Sowell said...

Mr. Carr, I would say it is a bit premature to discredit or dismiss the Power Tree flywheel storage device. We don't yet know for how many hours their device will produce power, and at what level. They may produce for 100 hours, which is just over 4 days. Or it may be 10 hours, or 3. We just don't know.

In any event, there is very likely the possibility of series operation, with three or more of the devices operating. The cost to install and operate will be key.

Roger Vaughan Carr said...

By "series operation" do you mean a transfer from one running down to another starting up, Roger? If so, I suspect friction and friends will degrade the amount of power stored quite dramatically.

However, I am not capriciously endeavouring to either discredit or dismiss Power Tree's development of a storage device. I will applaud a success; but suspect the laws of physics are taking some bending here as so far described.

Roger Sowell said...

Mr. Carr, in this context I refer to several ESS all charged up and spinning, so that as one is depleted into the grid, the next kicks in, and so on for as many ESS as one has operating.

It would make little sense to charge one ESS by discharging another.

Re windmill monsters something less than feel-good icons of visual pollution, perhaps you have not seen the power grid numbers for the state of Texas, with the amount of power generated by windmills. It is a non-trivial amount. see

Roger Vaughan Carr said...

Couple of comments on your last post, Roger (and a note to please wind down the implications that I am being negative or abrasive because I am not):

You note: " one is depleted into the grid, the next kicks in, and so on for as many ESS as one has operating. ... It would make little sense to charge one ESS by discharging another."

Which I believe validates my point that success will depend on duration of storage (spin). Cranking a weight up a hill or water into a dam allows storage of energy for an unlimited time. Spinning a wheel will have a limited duration; which we have been through.

You quote me: "...windmill monsters something less than feel-good icons of visual pollution," which I stand by until the power generated by the Texas windmills can be stored against a calm -- then my beholding eye will see their beauty.

M. Simon said...

If they are going to get long term storage. They need to put the flywheel in a vacuum. Magnetic bearings are also a requirement.

On top of that peak wind is in the winter and peak load is in the summer. A PV, wind, storage - system may be the best option for renewables.

To make it economical (support the storage component) I'd estimate that the cost of wind and PV electricity would have to come in at 1/2 the cost of a coal burner.

It will eventually happen (series production of 10 MW turbines would be what to look for, PV is expected to cross the equal cost point around 2012). But the time frame would be about 2020 or later. Plenty of time except for the hysterics.

You might want to look into the work Argonne has done on Halbach arrays and low loss magnetic bearings.

Here is a paper from 1995.

M. Simon said...

Halbach Technology For Transportation

M. Simon said...

US Navy work on flywheels

Roger Vaughan Carr said...

Fascinating read in the links you supply, M Simon... but don't forget the bungee cord!

Of particular interest to me:
"The results have been so promising that NASA has awarded a three-year contract to the team to explore the concept as a way to more efficiently launch satellites into orbit."

"The first section of the test track uses a set of electrically energized track coils--aided by a stretched bungee cord--to reach this speed."

But I could not get a tie-in with the flywheel and power storage?

Roger Vaughan Carr said...

Or perhaps the Drumm cell could help the windmills smooth their load? (the Drumm Traction Battery)

"The standard rate of charging for a single traction cell of weight 112 lb and allowing for all losses in efficiency, corresponds to an input of 0.134 effective watt-hour/lb/minute which is about four times the normal rate for alkaline cells. In practice the same cell is normally discharged at 400 amps and at an average voltage of 1.65 volts which is equivalent to about 0.1 watt-hour/lb/minute.
"This figure is twice the highest discharge rate of other alkaline cells. But over and above this the current can, when required, be raised to 1000 amps for limited periods, corresponding to an energy delivery of about 0.22 watt-hour/lb/minute - a very high rate indeed. The Drumm cell deals with these loads quite comfortably and with no sign of deterioration. Another feature of the Drumm battery is that it cannot be damaged in any way by frequent over-charging or over-discharging. Neither can prolonged reversals of current through the battery when discharging, cause any harm. The maximum allowable cell-temperature for this battery is 45 oC. The working life of the Drumm battery has been assessed as not less than ten years. Tests carried out on the nickel grid show that it can withstand hundreds of thousands of cathodic and anodic polarisations. The electrolyte is comparatively cheap and can be changed or renewed at very small cost."

"Drumm battery powered train
"The original Drumm train was constructed in the Great Southern Railways workshops at Inchicore. The weight of the train with passengers was about 85 tons. There was seating accommodation for 140 passengers. The train could accelerate from standstill at about 1 m.p.h. per second and attain speeds of 40 to 50 m.p.h. with ease."

James J. Drumm

From a story picked up on Watts Up With That?