Re: Methane and other winds (was Re: alternatives to big oilandifthey can ...

From: Charlie Stross (
Date: Mon Feb 07 2000 - 06:19:13 MST

On Sun, Feb 06, 2000 at 01:04:04AM -0800, Michael M. Butler wrote:
> I think not. As best I can recall the subs you're thinking of used
> catalyzed high-concnetration hydrogen peroxide H2O2 when they were
> operating in "rocket" mode. They got steam to run turbines and oxygen as
> output. Not sure what they did with the oxygen.

They didn't quite work that way. IIRC, they just catalytically cracked
the high-test peroxide to provide oxygen which they fed into their
deisel engines. The exhaust was CO2 plus water vapour, and was either
stored or vented.

Conventional subs of the day had two propulsion systems: diesel engines
for running on the surface at up to 20 knots, and battery-powered
electrics, for submerged operations. The batteries were charged by
the deisel engine (via a generator) while on the surface. (For this
reason they're best considered as submersible boats rather than true
submarines in the same sense as a modern nuclear boat.)

Normal subs could make maybe 10-12 knots submerged for a couple of hours
on battery power, or 4-5 knots for 12-24 hours. A peroxide boat could
charge along at 20+ knots for a day or two; this enabled them to make a
much more successful getaway after an attack -- it massively increased
the area that would have to be searched by ASW craft hunting the sub.

Peroxide boats still carried batteries and schnorkels; the use of
peroxide to let them run their deisel engines while submerged was basically
an emergency get-out-of-trouble-fast measure. It was also sodding loud,
which is why the technique fell out of favour with improvements in sonar
after the war. (Electric and nuclear boats are _much_ quieter.) There's
apparently some work in hand (in Norway, IIRC) on resurrecting the idea,
this time using a very quiet Stirling cycle engine and storing the exhaust
gasses in a double-hull arrangement.

-- Charlie

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