least polluting rocket fuel

Roy Smith wrote:
In article .com,
wrote:

Are there any rocket fuels -- existing or potential -- that are less
polluting than kerosene or hydrogen? If so, are any of them
economically feasible?

I can't imagine anything less polluting than hydrogen. The only possible
combustion product of hydrogen is water, regardless of temperature or mix
ratio.

Several people have mentioned this, but it's not quite true.
Of course, only water comes from the reaction of oxygen and hydrogen.

But, when a several km/s jet of any form hits air, it's quite hot and
energetic enough to cause nitrogen oxides to form.

wrote:
Are there any rocket fuels -- existing or potential -- that are less
polluting than kerosene or hydrogen? If so, are any of them
economically feasible?

I'm surprised no one has suggested solar power. ;-)

A simple ground or space based variable-focus mirror and a solar-heated
ramjet is all you need! Needs, ah, a few details worked out....

G. R. L. Cowan wrote:
A rocket with liquid air for propellant,
powered by a laser on the ground,
would be a little cleaner than an oxyhydrogen rocket.

If you kept the liquid air fairly cool when you zap it with a laser,
sure. However, if you heat that liquid air with the laser to several
thousand degrees, you're probably going to get a lot of nitrous oxides.

Mike Miller

"Ian Woollard" writes:

(Manufacturing hydrogen from electrolysis of water using nuclear power,
in principle is clean,

Yeah. And the nuclear waste will be flung, using beanstalks made
of hemp, right into the sun, where it can again be called nonpolluting...

best regards
Patrick

wrote:
Are there any rocket fuels -- existing or potential -- that are less
polluting than kerosene or hydrogen?

HYDROGEN???

When hydrogen burns, it releases H2O. While the dangers of dihydrogen
oxide (more commonly called "water") are well known, it is generally
not considered a pollutant.




--
Sea Wasp
/^\
;;;
Live Journal: http://www.livejournal.com/users/seawasp/

Hydrogen is quite polluting since it takes a lot of energy to
manufacture; and a lot of CO2 and doubtless other pollutants get
generated. The fact that it produces very little pollution when the
rocket flies isn't really the point.

Fuels like bioethanol and don't produce net CO2 since the plants suck
an equal amount of CO2 out of the air when they grow, so you're left
with essentially no pollution - from the fuel anyway.

The rocket itself is a different story- aluminium needs quite a bit of
energy to produce and CO2 is liberated during the electrolysis that
makes it from the ore. Still, a BOTE calculation suggests that this is
a much smaller amount of pollution than the fuel.

On Fri, 27 Jan 2006, Ian Woollard wrote:

Date: 27 Jan 2006 18:23:01 -0800
From: Ian Woollard
Newsgroups: sci.space.tech
Subject: least polluting rocket fuel

Yes, bioethanol and liquid oxygen. And yes, pretty feasible. You might
also be able to use some suitable vegetable oils to replace kerosene
with minimal modification to the engines. Doing it that way, you'd get
minimal pollution (a bit of nitrates produced during the burn, but not
too bad.)

Hydrogen is only less polluting if you make it in a non polluting way,
but hydrogen is actually commercially manufactured from methane; is
energy intensive and probably generates more CO2 than a rocket burning
kerosene would.

(Manufacturing hydrogen from electrolysis of water using nuclear power,
in principle is clean, but is never done on a large scale; the energy
required is prohibitive.)


-----------------------------------------------
It is my undestanding that current large wind turbines create electricity
at 4.5 cent/KWH (with no subsidies) on the average. At that rate it costs
about $2 to produce an amount of H2 by electrolysis which, when burned in
a fuel cell, is
equal to a gallon of gasoline, when burned in a combustion engine. For
automobile use you have to add another dollar for all the remaining costs
of distribution, including profits. So $3/gallon equivalent of gasoline
to produce H2 by electrolysis is hardly prohibitive

In fact the costs would be lower, because the 4.5 cents/KWH assume that
you are using *clean* electricity to perform electrolysis. A major part
of wind turbine costs is the conversion of mixed frequency current to
direct current and then back to clean 60 cycle current -- something that
is needed to run computers and TVs but not for electrolysis.

I don't know why this myth of high costs to clenaly produce H2 persists.
However,
H2 is only truly clean when burned in a fuel cell. When burned using
combution it produces Nitrogen oxides.


-- Larry Gales

In article , Patrick Schaaf
wrote:

"Ian Woollard" writes:

(Manufacturing hydrogen from electrolysis of water using nuclear power,
in principle is clean,

Yeah. And the nuclear waste will be flung, using beanstalks made
of hemp, right into the sun, where it can again be called nonpolluting...

What? And upset the delicate ecology that may exist on the Sun? After
you've polluted the Sun, an unprotected person standing on the surface
would quickly die of radiation (even if they go at night).

--
David M. Palmer (formerly @clark.net, @ematic.com)

According to: http://www.stardrivedevice.com/electrolysis.html a
'gallon equivalent' is 1kg of hydrogen and would in fact cost slightly
over $4 to produce by electrolysing water. However, for rocketry
purposes this neglects the liquification costs which are quite
significant.

Last time I heard, NASA was purchasing their *liquid* hydrogen for
about $7/kg, and that wasn't even environmentally friendly hydrogen,
which is more expensive.

"Ian Woollard" wrote in
ups.com:

According to: http://www.stardrivedevice.com/electrolysis.html a
'gallon equivalent' is 1kg of hydrogen and would in fact cost slightly
over $4 to produce by electrolysing water. However, for rocketry
purposes this neglects the liquification costs which are quite
significant.

Last time I heard, NASA was purchasing their *liquid* hydrogen for
about $7/kg, and that wasn't even environmentally friendly hydrogen,
which is more expensive.

So the only acceptable propellants are wind/solar powered
electrolytically derived and liquified hydrogen and oxygen?
We certainly don't want nuclear-comtaminated fuels, do we?
(sarcasm)

--Damon