[Agren]

Hi, This link was sent to the Web Links here. A quick look tells me it's a bit suspect, I don't really like magnetic-anything. So, before I add it to the links section I'd like to know if anyone has anyting to say about it, positive or negative

http://www.energynews.gr

[gg3]

I second Aaron's flatulent-noise response. In essence this idea comes down to using magnetic tape as an energy storage medium, and/or using the playback head as a kind of stator in a generator, where the passage of the tape is equivalent to the movement of a rotor. However the energy density of the medium would be pathetically low. I can't even think of an application where a stored waveform at a given frequency would be useful, that couldn't be fulfilled better by generating the same waveform using a software-controlled oscillator.

So, what was that guy smoking, anyway?

[pps]

I guess that kinda sums it up I was hoping that the sender would show up and explain himself, let's give him a day or two

WHOEVER (OR YOURSELF) SAY THAT HE OR SHE DOES NOT UNDERSTAND The Physical Principles Of The PPS Project, TELL HIM / HER TO SAY IT IN THE POLICE AUTHORITIES.

ALL THE Judicial Officials AND Policemen around the World KNOW IT. It is ABSOLUTELY LEGAL to tell OPEC that the Global Economy DOES NOT NEED THEIR OIL. IF THERE IS Terrorist Action against you, THEN the Court Of Crimes (flagrante delicto) INTERVENES in Ex Officio.

ALL THE Judicial Officials around the World KNOW THAT the natural gas companies are THE ACCESSORY before the fact (they are the CULPRITS of the "war on terrorism").

Basil Dimitropoulos
104 - 106 Kremou Street, Kallithea, Athens 176-76 Greece
http://www.energynews.gr
TEL: +30-210-9590530

[EnviroEngr]

I don't think this one's tuned to our frequency.

[Kingcoal]

What gets me about the perpetual motion/free energy crowd is how they never seem to build and demonstrate anything these days. I've seen old movies showing all kinds of ridiculous inventions being bravely demo'ed by the inventor. They mostly failed to work, but you had to hand it to the inventor for his/her bravery.

I mean the last time we saw anything was the cold fusion bottle.

[ohanian]

Hi,

This link was sent to the Web Links here. A quick look tells me it's a bit suspect, I don't really like magnetic-anything. So, before I add it to the links section I'd like to know if anyone has anyting to say about it, positive or negative

http://www.energynews.gr

thanks in advance
Agren
Web Links admin

Using the movement of magnetic material to produce electrical energy has already been done in the year 1832. The BIG LIE is that the output energy is higher than the input (mechanical) energy. Whether the magnetic material is a big magnet or plain magnetic tape is irrevelant.

http://en.wikipedia.org/wiki/Dynamo

[nth]

I got questions regarding this:

How energy efficient is Helium as an energy carrier?

Why can't we use Helium in wind mills to store energy instead of the proposed Hydrogen?

Thanks.

[Jack]

Umm...How, exactly, do they use an inert gas such as Helium as an energy source or transport?

And how does it use Helium as an energy source? Unless they liquify the stuff and run it through a sort of steam engine...

You might want to check the information. It may be that they use liquid helium to chill superconducting magnets...but that probably wouldn't be very helpful in generating electricity.

[BrownDog]

Among the uses of helium is as a shielding gas in arc welding (mostly TIG or GTAW). Since it is inert, it doesn't react with the molten metal and also displaces oxygen and nitrogen, which would otherwise weaken the metal. It's definitely not a fuel.

This is kind of obscure, but there will one day be "peak helium". As you know, it's lighter than air, so it drifts out of the atmosphere and into space, never to be recovered. And short of fusion, there's no way to make more.

[0mar]

Most inert/noble gases actually come from gas fields.

[markam]

helium is used for cooling in turbine generators and such since it has a much higher efficiency than air. I am sure that is what it is used for in MRIs

[aflatoxin]

I'm pretty sure that the (liquid) helium is used to produce the temperatures needed by the materials used in the magnet to superconduct.

Superconductors allow much higher fields to be produced with a given amount of energy. Newer materials can superconduct at higher temperatures than helium, but there may be other problems regarding magnet design.

I had a MRI recently. My impression was that the machine used a prodigious amount of electricity.

Hydrogen gas is used as a coolant in electrical generators at power plants because it is lightweight thus imparting less aerodynamic drag on the moving parts. As an added benefit, it had a high heat capacity, and can carry a lot of heat away, where it is removed with a heat exchanger, and the hydrogen is then recirculated into the generator.

Helium is used in welding, along with argon and CO2. Helium is used to weld aluminum because it is a better insulator than argon, thus creating higher arc voltages. This creates a higher arc temperature, which is useful with aluminum because it is such a good conductor of heat. Most welders use a mixture of Argon and Helium for economy.

Hope this helps to answer your questions

[satjeet]

i work in a radiology department - they get the energy off the grid - helium or maybe even nitrogen is used as a coolant -

[MicroHydro]

The neobium magnets in MRI machines need to be cooled to liquid helium temperature to operate. Peak natural gas (circa 2015) is peak helium. By the end of the century, helium will be gone. Unless new superconductors are found that can create the high field strength needed for medical MRIs at LN2 temperatures, MRIs will fade into history.

[ChumpusRex]

As has been stated already, the helium is just a coolant.

The electromagnet is a superconducting coil of wire. Interestingly, because it is a superconductor - once the coil made superconducting it can be energised from the grid. However, once energised, no energy is lost from the coil because of its superconducticity - so the coil can be disconnected from its power supply, yet will retain it's current flow and magnetic field.

Note that the helium is not an energy source - the magnet is initially energised with electrical energy (although this is a one-off event), and huge amount of energy are needed to keep the helium cold and minimize evaporation.

Currently most MRI systems use low-temperature superconducting wires cooled with helium, but there is a lot of interest and a few prototypes of devices that use high-temperature supercouducting materials cooled with liquid nitrogen. This would be a huge decrease in cost - the helium alone costs about $30-50k per year, let alone the energy needed to keep it cool.

You can even make MRI scanners with permanent magnets - they look like huge horseshoe magnets on their side. They just aren't as good as the superconducting versions. Hitachi permanent magnet MRI scanner

[nth]

Thank you guys!!
That was very helpful.
I worded wrong... helium obviously is not an energy source.
I didn't know how helium worked in MRI.

Now, I know that it is used as a coolant.
I just heard MRI magnets can store energy and keep it for a very long time and the only way to demagnetize it was to release all the helium.
This all make sense now.

thanks, again.

[ChumpusRex]

I just heard MRI magnets can store energy and keep it for a very long time

Yup, that's it. Once you have power flowing through the coil, you simply connect both ends of the coil together with a superconducting switch - and the electricity will keep flowing in a big loop for as long as the whole circuit remains superconducting.

Normally, there is a discharge system, an external non-superconducting circuit is attached to the magnet, and the superconducting switch is disabled - forcing electricity through the non-superconducting circuit where there energy will be released as heat. Because no heat is released near the helium, you don't waste any.

There are circumstances where superconduction may be lost inside the helium area - this is a big problem. Essentially, a severe fluctuation in the magnetic field (e.g. someone allows a large iron object into the range of the magnet) can cause the superconductivity to fail within the elctromagnet itself. If this happens, all the energy in the magnet is converted into heat in the helium circuit. This causes the helium to boil and evaporate extremely quickly - This enormous volume of ultra-cold gas has to escape through huge vent pipes. The safety vent pipe for the scanner at my local hospital is nearly 18" in diameter!

If this happens, the scanner remains out of action until you replace the $5k of helium you boiled off, and have the manufacturer come out and recharge the magent.

[nth]

ChumpusRex,

So i was told you cannot shut this thing off and turn it back on every morning like a computer. You basically leave it on period.
Even if you unplug it, the magnet is on and will be on for awhile.

Is that true?

[ChumpusRex]

So i was told you cannot shut this thing off and turn it back on every morning like a computer. You basically leave it on period.
Even if you unplug it, the magnet is on and will be on for awhile.

That's correct. The magnet requires no energy to maintain the magnetic field.

Once the electromagnet is charged, it will stay charged until the energy is released (either deliberately through a discharge circuit, or because the superconductiivty fails).

Even if you cut off all power, the magnet will remain energised. however, the helium would eventually evaporate (this would probably take a few days - weeks) and the superconductivity would fail - at which point the magent will lose its energy.

(Edit - removed reference to cooling systems. Most systems do not have their own helium coolers - instead the helium is allowed to evaporate and fresh helium is delivered on a regular basis).

Some MRI scanners do have cryocoolers to help reduce the evaporation of helium.

Most scanners do have an option to discharge the magnet - mainly for safety reasons - however, this is very rarely used.

The magnetic field is so strong, that the forces generated in the actual electromagnet itself are measured in tonnes. Discharging the magnet releases these forces, and there is a small risk that when this happens the magnet will fracture or buckle. With the going rate for a new magnet at about $ 1 million, you want to avoid this as far as possible.

Similarly, charging the magnet usually needs to be done by an engineer from the manufacturer - expensive, and best avoided.

As an aside, there is a lot of interest in cryogen free superconducting magnets. Essentially, cooling equipment is getting smaller and more efficient, meaning it is possible to attach the magnet directly to a piece of metal (e.g. copper) which is attached to the cooler. No need for any liquid helium or nitrogen. There are some prototype MRI scanners which use liquid-free superconducting magnets.