Generators

[SolidHydro]

Who makes the most efficient generators? By this, I mean,...who makes the generators that require the least amount of hp. "Low Friction".

Are there frictionless?

Under full load, I'd like it to turn freely.

I do not want to require huge hp.

[johnlm]

Im not sure what company makes the most effecient generators; however friction as I understand the definition is not a big issue.  I would define friction as the power losses in the bearings, which I suspect are likely less than 1% of the loss (or making it difficult to turn) in a generator.  I would guess many comercial generators / alternators are in the neighborhood of as low as 65% to as high as 90% effecient.  You say you want to use low horsepower.  How many watts do you want to generate?  Take that number and divide it by 746 and then divide that result by a typical effeciency of say 75% (0.75) to get the number of horsepower it will take to run the generator to get the output wattage you desire.  Low HP in = low wattage out.

[SolidHydro]

I understand that John, ....I should have stated "electromagnetic friction", bearing friction (cough), is the least of my concern.

For example, alternators are used over generators, because they require less hp. I am seeking an alternator which spins as freely as possible under load. It's application is irrelivant,... wind, hydro, engine, etc....