[Stoves] Re Alexis Belonio article

[David G. LeVine]

>A 135 HP elecric DC motor is really large and heavy.  I don't have a 
>mass on hand, but it is a big device.  And expensive.  The frame of 
>the vehicle also has to be strengthened hold it up.

A 125 HP AC motor weighs about 1,000 lbs and costs $1,600 surplus, 
see 
http://www.surpluscenter.com/item.asp?UID=2007041111371056&item=10-1977&catname=electric 
for details. Go to 400 Hz and its weight drops dramatically.  AC 
motors with big sized using VFDs are generally better choices unless 
you are running a locomotive, where the extra weight is helpful.

Technology changes.

>A 135 HP single cylinder hydrogen engine is tiny, like a lawnmower 
>engine.  Smaller mounts, smaller space required.

Now this does not sound reasonable.  Why does a hydrogen powered 427 
Cobra ( 
http://www.clean-air.org/Hydrogen%20Cobra%20Story/Hydrogen%20Cobra.htm 
) develop 1/2 the BHP that it does on gasoline or create unacceptable 
levels of pollution?  With 270 BHP and 427 CID (7 Liters), a 135 BHP 
hydrogen engine would need about 215 CID (3.5 Liter) and that is not 
a lawnmower engine unless it ran at VERY high speed.  Running at very 
high speeds has issues with ring life.

>So, the efficiency calculation has to include the power needed to 
>accelerate and brake (regenerative?) the extra mass of the DC motor 
>for the whole life of the vehicle.  Maybe the motor/regenerator 
>beats the light engine in city driving.
>
>I would be interested if someone can show us what a 135 HP DC motor 
>would look like on the web.  A 100 KW motor is a sizeable chunk of metal.
>
>Suppose the DM motor weight 15 times as much and cost 5 times 
>more.  At what cost of electricity would the cheaper route be 
>internally generated hydrogen over a three year period?

Actually, a hydrogen motor developing the same BHP runs about 1/2 the 
weight of a low frequency AC motor, BUT it needs a transmission and 
cooling.  By the time you add those in, it is a wash except that you 
are comparing apples and gorillas.

An electric motor has a service factor to consider and can run 2-3 
times its' rated power for short bursts (like starting the compressor 
in your refrigerator or accelerating from a stop.)  In general, an 
electric motor needs about 1/2 the HP of a reciprocating IC engine in 
a normal vehicle for similar performance.


David G. LeVine
Nashua, NH  03060