Re: Hydrogen cells, diesel electrics

[Jon@AppliedThought.com (Jon Hylands)]

On Wed, 08 Oct 1997 16:26:13 GMT, Jon@AppliedThought.com (Jon Hylands)
wrote:

On Wed, 8 Oct 1997 10:45:02 -0400 (EDT), Coast Guard Kiteman
<exfloridians@ecsu.campus.mci.net> wrote:

>         I'm thinking along two different lines that I haven't seen in the
> short time
> I've been on this list.
> 
>         First is propulsion.  Instead of using batteries, has anyone
> investigated using hydrogen/oxygen (or hydrogen/air) fuel cells?  Several web-
> sites for fuel cells are on the internet.  It seems the advantages would be (1)
> longer endurance time, and (2) qucker turn-around time.  Just replenish your
> hydrogen supply (using a hydride tank which would also act as ballast), which
> would be quicker than recharging batteries.

I think it would be cool. Does anyone have any hard info on how effecient a
fuel cell is (in terms of electrical output to weight and electrical output
to volume) compared to batteries?

>           I know U.S.Submarines<?>, the folks advertising on the web with
> the multi-million $ private subs, are going diesel-electric.  I don't like
> that because as soon as you get 1 inch below the water (unless you're using
> a snorkel), that diesel becomes completely useless dead-weight.  Then your
> batteries (which you've been dragging around on the surface) take over until
> they're exhausted.

Well, no, actually, some of the diesel-electric systems I've heard about
are "closed-loop" systems that (like a rebreather) can allow an engine to
"breathe" with no external air supply or exhaust. I believe the British
navy has perfected such a system. They recycle the exhaust, chemically
remove all the bad stuff, and reinject it into the engine with a small,
fresh supply bleeding in from storage tanks.

Also, you can go (for smaller amounts of time) with a system like the VASH
uses, which is basically an on-board compressor to fill an air tank while
you're on the surface, and then when you go under water the engine breathes
from this supply, and just exhausts into the water. The VASH can only go
under for two minutes at a time, but then again they're feeding a 200 HP V6
two-stroke gasoline engine in a sub the same size as mine that only weights
600 lbs...

>         And yeah, there's not a hydrogen filling station on every corner.
> Yet.  But
> for our use here with personal subs, I'm sure that could be overcome.  I mean
> if you're building a submarine from scratch [and you'll need a lot of
> scratch <g>],
> you're going to have to build some support equipment on your own, too.

It's not hard to make hydrogen (its a by-product of electrolysis), but you
do need an external electricity supply. So, you have a big tank at home and
a system for generating H. You do a transfer to your sub's tank(s) in the
morning, and turn the system on when you leave. While you're off having
fun, the system is slowing turning water into hydrogen and oxygen, and you
capture both (H as fuel, O2 for the rebreather).

The really nice thing about fuel cells is that if you could refill your
tanks from shore in a matter of minutes, instead of waiting for 12 hours to
recharge your batteries.

But, of course, for really small subs, the critical thing is power output
compared to volume. If it's better than batteries, you'd have it made. If
not, well, you're out of luck. From the limited amount of research I've
done, I'm inclined to believe that batteries are more effecient per unit
volume, but then again maybe someone knows otherwise...

Later,
Jon

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- Jon Hylands Jon@AppliedThought.com http://www.AppliedThought.com/jon -
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