# PMA and High RPM from a turbine

## Main Question or Discussion Point

PMA and High RPM from a turbine....

Hey Forum,
I am working on a plan to build a recharging setup. What I want to do in theory is take a jet turbine or a smaller RC turbine that burns bio diesel and turns at around 60,000 RPM. I want to take this high speed rotation into a chain or belt system spinning 1-4 PMAs(Permanent Magnet Alternators). This generated electrical energy will then be stored in large super capacitors or 15 deep cycle batteries.

What I want to know, first is this possible? Also, I am thinking that really high currents will destroy the batteries, hence the use of the super capacitors. Can I still recharge the batteries from the Capacitors? I have found some PMAs that will put out 100 amps, but the website states that the horse power is unknown, so its just a reference. I don't know what the HP would be for a turbine, so I would just have to use an average number. I am thinking that there will be large amounts of heat, and the possibility of burning up the PMAs at that speed, so maybe throttling down the turbine, or using a reducing gear?

I want to calculate how long it would take to recharge the battery bank from this type of setup burning the bio diesel into the turbine. This is possible, but I need help assuming some values.

Lets figure: Battery - 225AH X 15 (# of batteries)
I could find very little on super capacitors and PMA specs.

Thanks,
Sounder

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stewartcs
Re: PMA and High RPM from a turbine....

I have found some PMAs that will put out 100 amps, but the website states that the horse power is unknown, so its just a reference. I don't know what the HP would be for a turbine, so I would just have to use an average number. I am thinking that there will be large amounts of heat, and the possibility of burning up the PMAs at that speed, so maybe throttling down the turbine, or using a reducing gear?
The horsepower for the turbine will vary by type and will be available from the OEM. I'd definitely use a reduction gear to drop the rotational speed. If you vary the speed you'll vary the output of the generator. All gas turbine generator sets I've encountered are constant speed turbines.

BTW gas turbines are already used for this application (e.g. ship power, industrial plants, power stations).

CS

Re: PMA and High RPM from a turbine....