Re: Ammonia as fuel

I think you're not quite right.
First, the LH tanks on a plane do not have to be that heavy - about
5% / hour vaporization would be perfecly Ok for the aitcraft, assuming
it can take off soon after fueling. Think of Space Shuttle - I beleive
it can take off many hours (24 ?) after fueling, and tanks there are
very lightly insulated.

The space shuttle can take off many hours after fuelling because
the tanks are constantly being topped off and it is spewing hydrogen
all over the place in the meantime. but perhaps the tanks themselves
will need to be only 4 or 5 times as heavy as a similar sized room
temperature liquid tank. Still quite an impediment to place on an
aircraft. Remember, the space shuttle is an example of what is
possible if you *absolutely do not care* about price.

Second, about the volume required to store fuel. This is the first
page that came up on a quick Google search:
http://www.kenya-airways.com/kqdispinfo.aspx?colm=74
Aircraft length 60m, fuselage diameter 6m, fuel capacity 170 m3. So
the same aircraft would require, let's say, 600 m3 of LH. With 6m
diameter, it will take about 23m long tank. So the aircraft will be
80m long, not 60m, big deal.

well.... that's at minimum, a complete redesign. now remember
here, that you can't simply extend the fuselage, you need to make it
wider as you make it longer for structural reasons which means you'll
need to carry more fuel. now, that extra structure has weight, which
means you'll need bigger wings. now, the new larger cross section and
longer fuselage will mean more drag, which means you'll need to carry
more fuel. so you see that this ripples and gets messy.

Third, I think large scale LH production, translated to the wheel
power, is about 20% efficient with currently known technologies, not
10%.

call it 15%. it's unrealistically high, and still totally
shitty.

If it turns out that there are some fundamental limitations on energy
density of rechargeble batteries (and it increasingly seems so), then
LH may be a very viable alternative. I think by "liquefied coal" you
meant synthetic hydrocarbons; they may be a way out, too, provided
that A. you have reliable and easy to purify source of carbon B.
"global warming" stuff is BS, which it may, or may not, be.

Prolly isn't BS. It is probably going to happen. however, we
have a better chance of giving up food than hydrocarbon consumption.

Okay dude, you've got a few problems here. The fuel on current
jets is stored in the *wing* look at relative volumes here and you
will see that 3 times the volume would fill half the fuselage as
well. That's one. 2 is that the high pressure cryogenic tanks that
would be needed are rather heavy, unwieldy, prone to leaks and
generally tetchy. Including the storage tanks, there would be no room
whatsoever on the plane for passengers. If it comes to running jets
on h2, we stop running jets.
Hydrogen is basically a non-starter as fuel. At best, the total
process efficiency is in the neighborhood of 10%. That's pretty
miserable.
The next generation of cars will either be fueled by a
combination of grid electricity nuclear derived, and liquefied coal,
or they will stay still. There are no other viable options, hydrogen
is simply too stupid to contemplate.


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