• Quick note - the problem with Youtube videos not embedding on the forum appears to have been fixed, thanks to ZiprHead. If you do still see problems let me know.

Flywheels energy storage?

Electric motors have great potential for propelling autos. They are simple, relaible, efficient, develop full torque at all speeds, and can recover energy when braking... But supplying the electricity to run the motors is a challenge.

I have thought for years that flywheels have the greatest potential because the energy conversion efficiency is very high and they can be recharged rapidly (so rapidly that almost all of the energy lost when braking can be recovered). While there are problems to overcome, it always seemed like they would be solvable without "new" technology.

Batteries charge too slowly, are inefficient, and have a limited temperature range. Regenerative braking requires a capacitor bank because no battery can absorb charge as fast as braking generates it. Despite years of effort, there have been no major breakthroughs in battery technology, and none seem likely at the moment.

Photoelectric cells are expensive and require more surface area than available on a vehicle. No drastic improvements seem likely in the next 10 years or so.

Hydrogen gas fuel cells suffer from low energy density of hydrogen gas and its propensity to leak out. Liquid fueled fuel cells require a conversion stage to release hydrogen on demand. Both types require large amounts of expensive catalysts. There is a great deal of development effort currently, but the technological problems are still a great challenge.

I hadn't heard about the super capacitors. That technology may also have some promise...
 
Walter;

----
quote:
The three hybrid vehicles I know off already charge batteries from braking, at any speed.
----

Well, If I understand correctly, flywheels have a much better recover speed. Chemical batteries are too slow storing energy, unlike flywheels or ultracapacitors, and braking times are very short (with the exception of running downhill).
Does the hybrid vehicles you know use chemical batteries?
As AP explained, hydrogen cells are capable of producing hydrogen back, but the process seems quite slow and complex. The helios plane use this capability, but for long periods of time (store during the day using solar power, release in the night).
 
A very interesting article about Chrysler Patriot;

http://www.adams.com/news/newsletter/spr98/satcon.htm

----
From the article:
Chrysler has put the Patriot hybrid electric race car project in mothballs pending technology improvements in the areas of turbine ceramic rotor materials and lightweight flywheel containment materials. Both the turbine ceramic rotor materials and the flywheel containment challenges are currently being addressed by the government/industry Partnership for a New Generation of Vehicles (PNGV).
----

It seems the security issues have stopped investment in this technology, because all information I keep finding come from 97/98.
What a pity, that Chrysler power-train engine really seems "the right thing".

Here is more info. An study with flywheel powered buses:

http://www.uptenergy.com/en/traction/casestudy2.htm

It seems it works better than chemical batteries, without the contamination.
 
patnray;
----
I hadn't heard about the super capacitors. That technology may also have some promise...
----

It's also news to me, but I knew other technology which makes good batteries: superconductors.
Commercial products comes under the name "Superconducting magnetic energy storage", or SMES. An example:

http://www.afrlhorizons.com/Briefs/Dec01/ML0009.html

However, the technology still can't be used for vehicles, although it shows promise...
 
SMES is impractical because it requires cryogenic temperatures. I know quite well that coils can store large amounts of energy. I was once knocked on my a** by the discharge from an antenna coil which had only a few volts but over a mile of wire in it. But coils seem best suited for short spikes, as in the surge compensating example. Room temperature superconductors are still only a dream.

I still think flywheels have the most promise. None of the problems facing them require breakthrough technology to overcome. No toxic materials or extreme temperatures are required. The drive motor/generator can be built on the shaft of the flywheel, eliminating inefficient mechanical couplings. They can be charged/discharged at a rapid rate regardless of their current state, unlike capacitors where the charge rate slows down as it becomes more charged (or the discharge rate slows down the more discharged it becomes)...
 
----
SMES is impractical because it requires cryogenic temperatures.
----

Is that really a problem? I guess some energy has to be used to keep the low temperatures, but how much?
 
I'm no expert, but I believe cryo requires at least two stages of compressors, which are relatively low efficiency mechanical devices.... Plus you'd have the added weight of insulation....
 
From the info recalled in this thread, I learned that the biggest problem with the flywheels is security. When the composite material breaks, it fasly becames a rain of hot red sand highly dangerous.
Googling a bit I have found that big advances in strong & light shields are being done lately:

----
From:
http://www.businessweek.com/magazine/content/02_41/c3803131.htm

Strong and Firm, Aerogels Come into Their Own

Translucent, light-as-air substances known as aerogels may finally find their way out of the lab. To be useful, aerogels must remain firm in different environments--a hurdle that most such materials have not cleared. Now, researchers at the University of Missouri at Rolla have discovered how to make a composite aerogel strong enough to stop abullet and capable of retaining its shape even when saturated.

Nicholas Leventis, a Missouri chemistry professor who led the aerogel research team, has found that by weaving nanosize plastic particles together with silica specks, he can make aerogels that are ethereally light but 100 times stronger than past versions. Using Leventis' recipe, the stuff still takes days to produce. On the other hand, it's dirt-cheap and can be molded into nearly any shape. The scientist believes his aerogel could be fashioned into bullet -proof vests or used as a porous medium to store jet fuel safely.
By Michael Arndt
----

So who nows, maybe flywheels still have some future...
 
Flywheels and hydrogen do not solve the "big" problem because they are energy storage not energy production methods. The big problem is where the energy will come from. Total energy expenditure from fossil fuel approximates total solar insolation of about 1 kw/m^2, so solar energy is hardly sufficient. Burning oil to spin up flywheels or decompose water into hydrogen and ox is not much of an improvement. The N word is still politically impossible, while fusion, perhaps more palatable, remains hopelessly out of technical reach. Geothermal, tidal, wind & other sources are limited, expensive, geographically restricted.

Unfortunately there is almost no public thinking on the big problem.
 
NWilner said:
Unfortunately there is almost no public thinking on the big problem
Click to expand...
I do not know what constitutes public thinking to you but the concerns about the use of fossil fuels as our primary source of energy looks to me to be one of the most thought about and talked about issues going.

Billions of dollars have been poured into research on various alternative fuel techniques. Billions of dollars have been spent on developing techniques for reducing pollution. Massive bureaucracies have been created to control pollution from the burning of fossil fuel. The ideas that have been put forth in this thread represent only a tiny fraction of the ideas that I have read about over the years for reducing reliance on fossil fuels.

How much more public thinking on the issue do you need before we would exceed your "almost no" estimate?
 
Tez, I took a look at the sight you linked to.

I wasn't able to understand much. What is their idea?

The specification section was really lame. I looked for something along the lines of power per weight, efficiency, etc. but didn't find anything resembling that. I never figured out what the basic concept was. Somehow compressed air has something to do with it, but what?
 
Davefoc, I think I can reply to this one, as the company is doing much of it's operations/gossip between france and spain.
Is just a big compressed air tank, no less, no more.
The idea is to put service stations where you can refill the tanks, and also sell you domestic air compressors...
The cars are for city use, and the tanks are BIG: 2x0,23 (meters). That's the reason the cars have this strange shape.
Air compressed tanks are far less efficient than flywheels, but less dangerous. Still, they are better than chemical batteries.
 
The Carter Administration talked about synfuel. I have not heard much about primary energy production since.

Even the Repubs are leery about restarting the nuke industry.

The other side of the equation, "conservation" is definitely an "out" subject in the present political climate.

The discussions have been about energy storage. This may be important in the short run, but it's not the big problem.

Maybe the choices aren't so hot right now: fossil like we're doing, for a while, with the attendant problems; some kind of solar (I include etOH fuels and even wood in "solar"); nuke; or wierd stuff like beaming energy from space solar collectors. Of these, none are very good options.
 
http://www.sciencedaily.com/releases/2003/11/031114071848.htm

AUSTIN, Texas -- Technology that significantly improves the ability of high-speed flywheels to store energy has been developed by research engineers at The University of Texas at Austin.

A flywheel made with the new technology set a speed record, spinning at 3,000 miles per hour, demonstrating the capability of storing 70 percent more energy than the same-sized flywheel made with current technology.
...
Last year, researchers at The University of Texas at Austin charged and discharged a flywheel 110,000 times with no change in performance. In addition, a flywheel system can be operated so that it wastes less than 5-10 percent of the energy stored as it is charged and discharged. By comparison, chemical batteries can typically be charged and discharged a few tens of thousands of times at best and typically waste more than 20 percent of the energy on charging and discharging.
Click to expand...
Somehow miles per hour doesn't seem like the right units for a rotating object.
 
Peskanov said:
There is a lot of info about hydrogen (as fuel for vehicles) on the media lately. Usually, experts reckon hydrogen is only a form of energy storage, because hydrogen has to be synthesized using more energy.

My question is, why is hydrogen a better energy storage?
What happens with common batteries? Too much weight, or maybe too contaminant?
And, what about flywheels? Flywheels are clean, have large storage capacity and slow energy leaking times...
Click to expand...

There aren't any really good batteries yet. If I can't run my laptop for eight hours on a charge, I'm not going to try to drive to Key West on one. Bateries have been improving a lot recently, but they have a long way to go. Maybe they're OK for commuting short distances.

Flywheels are interesting. My father told me many years ago that there were some mountain trains in Switzerland that ran on flywheels. Some buses, I think, use flywheels. A couple of problems are that you're basically limited to turning on one axis, so maybe you could have horizontal flywheels in Iowa but probably not in San Francisco, and second, do you really want to be around if someone gets into an accident and the case of the flywheel gets ruptured? At least hydrogen just burns; it doesn't run after you.
 
Flywheels would suck as a power supply for small electronics. Can you imagine the fustration engendered in just trying to turn the thing over?
 
Cars? What about houses? It seems perfect for storing unused energy from a day of solar/wind generated power. Keep it encased in concrete so safety isn't an issue.
 
You must log in or register to reply here.

Back
Top Bottom