Mic wrote:
Perpetuated Motion
Electric propulsion for boats: A century-old technology may just be
the wave of the future

LINK:

http://www.cruisingworld.com/article...ID=396&catID=0

" Advocates for diesel-electric propulsion list among its virtues that
it's clean, quiet, efficient, and requires very little maintenance.
Another advantage frequently noted in connection with the STI system
is the ability to make electricity--to "regenerate"--when the boat is
under sail."

"While internal-combustion engines are typically described by their
horsepower rating, STI's motors are named for the torque they develop.
An ST 37 puts out 37 foot-pounds of torque or 6 horsepower; Tether
recommends using it on monohulls up to 32 feet and 10 tons or to
replace diesel engines of up to 24 horsepower. An ST 74 puts out 74
foot-pounds of torque or 12 horsepower; Tether recommends using it on
monohulls up to 50 feet and 16 tons or to replace diesel engines of up
to 48 horsepower."


This is cool. But, lead acid batteries and high voltage DC and salt
water are like rocket fuel, deadly as chlorine.

A Canadian (British) submarines had a fire recently that seems to
point to the biggest drawback.

Lithium iron batteries are way dear, yet.

The steam idea; now what if, when you made hydrogen electrically
from water, instead of throwing away the pure oxygen, you stored it
and then introduced it into an I.C. engine that burned hydrogen?

Would that be a steam engine? How efficient and how large or small
could such an engine be?

I know, we haven't figured out how to corral big lumps of H2, yet,
but who knows what will come along.

Isn' it unfortunate that we cannot yet efficiently derive
electrolyzed O2 as a liquid? Can hydrolysis occur at very cold
temperatures, under pressure? Seems to me it shouldn't matter too
much, as the atomic bond of water might not be bothered much by
ambient considerations.

The nicest thing about all that is that if you spring a leak in the
system, the water around the boat might get cold enough to walk on.

'Gorra, If gasoline is dangerous on boats, how about pressurised
supercold O2?

Oh, and sails inflated with H2?

On subject, the balance in such a subj. electrical system, it seems
to me, would be a 5 hp charger and a 20 hp, 20 minute battery drive,
or about that. In a blow at sea, no self respecting sailor would
prefer to rely much on the engine, when the wind is so free, if
wild. Any sailboat that cannot sail might never expect to be able to
power out of a storm.

I still want to know how an engine would work if it dispensed cold
instead of heat. Liquid nitrogen is more benine than gasoline, and
could be used to suck heat through an engine if the heat source is,
let's say, relatively infinite, being represented by the enormous
heat stored in the liquid water of the sea.

It's heat would vapourize the LN2, providing gas volume to be
harnessed in an "external combustion" steam type engine, leaving in
it's wake only cold water, perhaps even ice, and still cool nitrogen
gas. Just think, free air conditioning as a side effect!

All that is lacking is a cold temperature LN2 low volume injection
pump of some sort, to introduce LN2 to a heat exchanger, boiling the
LN2, providing overpressure and volume to drive a piston.

A small bore, cold environment injection pump could generate a large
volume of cold gas in a heat exchanger which would gain power from
being warmed by the sea.

A leaking LN2 tank (dewar) could asphixyate cabin occupants, so must
vent overboard. Anyone being asphixyated by evaporated liquid
nitrogen would likely wake up from the increasing cold before
expiring. If half of the nitrogen and oxygen in a cabin were
replaced by pure cold nitrogen, the ambient temperature would freeze
the nose and the water in the exhalations passing through your nose.
When it gets that cold, all your nasal hairs freeze together and
pull on one another, causing pain, and that should wake you up
before more than half of the oxygen is displaced from the room. Ask
any musher about that cold effect.

You can make your own liquid nitrogen. All you need is a good
compressor and a heat exchanger, which stores potential energy in
the form of a temperature differential, in the environment and an
insulated cold tank until you want it back. Using a windmill to pump
air to provide storable LN2 might even work.

Terry K