[acsinuk (OP)]

The green hydrogen fuel has to be made by electrolysis of water at say 15p per kWh. Then the gas has to be pressurised to 150 bar and shipped to a new fuel depot which might add possibly a cost of 30p per unit which in terms of physics is possible but the economics is suspect..
Rehab old nuclear stations with mini nuclear units enclosed underneath a lake full of water.  Safer than a submarine and no huge concrete structures to waste health and safety money on.
But climate change is caused by high CO2 in the air which is caused by the demands of increases in world population. 
Look at Cox's Bazaar, it had 700,000 Rohingya  refugees in 2017 fleeing Myanmar but now has over a million with kids/teenagers with no jobs and no hope of improvement in the future unless they can escape from this frustrating camp poverty.
Who is responsible for this unsustainable 20% increase in the population in refugee camps but those who think they are doing the right Christian thing by feeding the poor?.
But understand this, free grain will undercut any local farmers production and stop locals refugees kids having jobs. Grain mountains rise in the west who have a months of supply in hand in case the harvest fails next year.  But when the new harvest is good and arriving at their grain silos the old must be disposed of; so why not give it to a NGO or UN? what better way of losing it?   This can only sensibly be corrected by getting the UN to acknowledge the problem and advise NGO's to treat free food aid with a contraceptive before passing it on.  Not treating free food is causing climate change due to population increase and much serious poverty in any and all refugee camps.

[Bored chemist]

treat free food aid with a contraceptive before passing it on.

Do you think that will become acceptable if you say it often enough?

[alancalverd]

I'm a long way from convinced about hydrogen powered planes.

The hydrogen-powered Tu-155 prototype made its first flight on 15 April 1988.

The technical problems have been solved by several manufacturers including Boeing and Airbus, who expect to have production aircraft for sale by 2035, but the problem of fuel distribution is more significant than for land vehicles. Piston engine planes  rarely fly intercontinental nowadays because AVGAS is hard to come by but JETA1 is widely available, and in consequence there is a lot of interest (but sadly not much success) in small aero diesels which can run on jet fuel. A significant part of the takeoff weight of an airliner is fuel*, so you plan to arrive almost empty. No problem if you only have a single route, like hydrogen trains, trucks and buses, but the economics of airlines are deviating away from 747s  and A380s, which need specialised ground handling,  towards 737/A320 and smaller ships that can "fill and go" from almost any municipal airstrip.

So the likelihood is that hydrogen aircraft will enter the market from the bottom, with small trainers and commuter planes using fuel cells rather than batteries (we already have battery-powered trainers with 1-hour endurance and a battery swap for the next pupil), long before hydrogen jets run scheduled flights.

*obviously less of a problem with hydrogen, with 3 times the gravimetric energy density (J/kg) of kerosene, but with only half of the volumetric energy density  (J/ltr)  you have to sacrifice loadspace for fuel tanks.

[alancalverd]

Lpg has a density lower in volume but higher for mass, one would imagine that it would be ideal for jet engines,

See reply #182 above. Same economic problem - there's plenty of JETA1 available everywhere - and no less CO2 emission than any other fossil fuel.

[Petrochemicals]

The green hydrogen fuel has to be made by electrolysis of water at say 15p per kWh.

You can actually be paid to take electricity.

Lpg has a density lower in volume but higher for mass, one would imagine that it would be ideal for jet engines,

See reply #182 above. Same economic problem - there's plenty of JETA1 available everywhere - and no less CO2 emission than any other fossil fuel.

Yes but it is lighter,

. A significant part of the takeoff weight of an airliner is fuel*, so you plan to arrive almost empty.

Given 747s are being retired for 777s because of the increaced efficiency one would think that anything lighter would be sized upon?

[alancalverd]

Quote from: alancalverd . Same economic problem - there's plenty of JETA1 available everywhere - and no less CO2 emission than any other fossil fuel.
Yes but it is lighter,

Not a lot. Similar problem to hydrogen - slightly higher energy per unit mass, but lower energy per unit volume,so you need to sacrfice loadspace. And again, not widely available, so only a limited number of routes can be flown.

from: alancalverd on Today at 15:32:15
. A significant part of the takeoff weight of an airliner is fuel*, so you plan to arrive almost empty.
Given 747s are being retired for 777s because of the increaced efficiency one would think that anything lighter would be sized upon?

Probably the first airliner type that will be available in a hydrogen format. The extreme range that allows London-Perth  in a single hop makes it the target for single-route zero-carbon flights, but I don't see hydrogen replacing liquid fuels for Ryanair/Easyjet short-haul  operations (like London-Belfast-Malaga-London in a day)  for a long time.

[Petrochemicals]

Not a lot. Similar problem to hydrogen - slightly higher energy per unit mass, but lower energy per unit volume,so you need to sacrfice loadspace. And again, not widely available, so only a limited number of routes can be flown.

Its10 percent lighter as per mass. Nearly there Alan, what possible reason(s) could there be for not adopting propane on board an airplane an energy saving measure? The airlines are throwing away perfectly good airframes and engines because of energy saving s of around 10 percent? A gas is even more handy as the stowage is even easier, a gas will fill the entire container it is in.

[alancalverd]

Its10 percent lighter as per mass. Nearly there Alan, what possible reason(s) could there be for not adopting propane on board an airplane an energy saving measure?

Because
(a) it's 30% bulkier so you need a bigger fuel tank
(b) the fuel tank needs to be pressurised, so is heavier
(c) the fuel isn't available in bulk at all municipal airports 
(d) rapid refuelling with LPG involves a pressure drop across the nozzle that can precipitate ice - can be quite a problem if it's raining!

No problem building a plane to fly in clear calm skies with liquid hydrogen fuel. Sadly, you have to fly in the weather you've got, with the fuel you can buy, so you design the plane appropriately. 

Not sure that anyone is throwing way perfectly good airframes. They have a certified life and at some point you need to overhaul or scrap major parts. Eventually it becomes cheaper to replace the whole ship, and a 10% reduction in fuel cost for the same journey amounts to a 2 - 5% increase in profit, which will repay the interest on the purchase loan. That said, airframes do last a long time. Some passenger-carrying 747s are over 40 years old and my little Cessna, at 50, is regarded as "a bit modern" by other spam-can aviators.

[Petrochemicals]

Safety Alan, gas has an ability to mix with air ever so easily, any leak and you have a bomb at 35000 feet, even if it doesn't bring down the plane there is a good chance a leak wil damage the control surfaces and the fuselage will be heading back to earth like a dart.

[acsinuk (OP)]

Safety is important but LPG and jetA1 are both hydrocarbons and will produce CO2 as a product so changing over is not helpful to climate change.
In fact climate change is due to increase in world population and not treating free aid food with a contraceptive  is making the situation much worse.  Look at the problem in Gaza and see what happens. They rely on free aid and are not producing their own food, most teenagers are out of work , huge unemployment being made worse by UN free aid.
To solve the problem all pro Hamas and anti Israel Palestinian's will need to be killed OR exiled 2000 miles into a Palestinian refugee camp by declaring themselves as refugees and asking the UN please to transport them 3,300 km to their new home.

[Petrochemicals]

Safety is important but LPG and jetA1 are both hydrocarbons and will produce CO2 as a product so changing over is not helpful to climate change.
In fact climate change is due to increase in world population and not treating free aid food with a contraceptive  is making the situation much worse.  Look at the problem in Gaza and see what happens. They rely on free aid and are not producing their own food, most teenagers are out of work , huge unemployment being made worse by UN free aid.
To solve the problem all pro Hamas and anti Israel Palestinian's will need to be killed OR exiled 2000 miles into a Palestinian refugee camp by declaring themselves as refugees and asking the UN please to transport them 3,300 km to their new home.

Are you proposing genocide?

[acsinuk (OP)]

No, to avoid bloodshed the Gaza city refugees need a new home and western Sahara would be ideal for them as they pride themselves as fishermen.
They will need to feed themselves and become self sufficient in every way using technical aid from everywhere but refusing free food aid unless it has been treated with a contraceptive.
This will avoid impoverishing their children and avoid the population explosion that is causing global warming. as is happening in Cox's Bazaar.

[Bored chemist]

No, to avoid bloodshed the Gaza city refugees need a new home

What's wrong with their old home?
Oh, I remember now...
It got invaded.

Palestine.jpg (53.48 kB . 512x339 - viewed 671 times)

How about moving the invaders instead?

Incidentally, we really need to knock this stupidity "refusing free food aid unless it has been treated with a contraceptive." on the head once and for all.
Do you understand  that children eat food?
Do you understand that the chemicals used in contraceptives would massively and permanently disrupt the development of children who ate it?

That's effectively proposing genocide again.
Just stop suggesting it- if you really think destroying them is a good idea but don't have the guts to say so explicitly, at least pretend you are a decent human and stop suggesting it implicitly.

[Petrochemicals]

No, to avoid bloodshed the Gaza city refugees need a new home and western Sahara would be ideal for them as they pride themselves as fishermen.
They will need to feed themselves and become self sufficient in every way using technical aid from everywhere but refusing free food aid unless it has been treated with a contraceptive.
This will avoid impoverishing their children and avoid the population explosion that is causing global warming. as is happening in Cox's Bazaar.

The people of western Sahara may complain. jeebus and Co where fishermen, so maybe a mission to the holy land in the name of Christianity would help?

[alancalverd]

gas has an ability to mix with air ever so easily,

The good thing about hydrogen is that it disperses very quickly, upwards, unlike kerosene and gasoline which hang around and stick to metal surfaces. A jet engine is a blowlamp with a turbo booster, quite unlike a fuel cell. And if your liquid fuel, be it AVGAS, JETA or LPG, didnt mix easily with air, it would be useless. 

[alancalverd]

their

Who "they"? The area you have marked as "Palestine 1946" was delineated in 1920 by the League of Nations and contained less than a million inhabitants with no single identity of tribe or nation, practically all of whom will have died by now.

Just a couple of days ago, the land was claimed as "ours" by the UN representative of the scum who govern Iran.

[Bored chemist]

Who "they"?

Gaza city refugees

[Petrochemicals]

And if your liquid fuel, be it AVGAS, JETA or LPG, didnt mix easily with air, it would be useless. 

Yes but they are gassified prior to, it would be impossible to make a jet with a liquid, it is the necessity of premixing the fuel with the oxydiser, even ice cars achieves this to some degree depending how hot the engine is. Premixing is a blow torch, not doing so is your kitchen cooker.

[paul cotter]

Not getting into the current phase of this thread but I think the politics should be dropped as it will only lead to flame wars with the thread being locked, my 2cents.

[Petrochemicals]

Not getting into the current phase of this thread but I think the politics should be dropped as it will only lead to flame wars with the thread being locked, my 2cents.

I agree Paul, possibly get the politics deleted.In an attempt to subvert such posts perhaps you should start a ?Paul's big thread on the middle east" in just chat, or would it be new theories?