Water vs Hydrogen discussion

[rancke]

It takes money to make money.

A stitch in time saves nine.

Steamer is a funny word in english, unless you want to be directed to the Ohio division, probably best not use it.

Definition of STEAMER
[...]
2

a: a ship propelled by steam

[Merriam-Webster]​

Business is risk averse, a dual stage fuel system would add a 50% failure rate to a standard system...

No, it would not. That's like arguing that installing a CB radio in a truck would increase the failure rate of the motor. Water tanks can be manufactured by TL 5 plumbers. Electrolysis is something TL 5 high school teachers can do with equipment the size of a breadbox. By TL9 one would suppose that the technology was reasonably mature.


Hans

 

[Dragoner]

A stitch in time saves nine.

Definition of STEAMER
[...]
2

a: a ship propelled by steam

[Merriam-Webster]​

No, it would not. That's like arguing that installing a CB radio in a truck would increase the failure rate of the motor. Water tanks can be manufactured by TL 5 plumbers. Electrolysis is something TL 5 high school teachers can do with equipment the size of a breadbox. By TL9 one would suppose that the technology was reasonably mature.


Hans

No numbers to back your business argument?

It's called a fuel purification plant in traveller, I somehow anyone would confuse one with a cb radio, seems to be a mite bit more important to your fuel system as well, curiuosly enough, scanning through CT, I see no merchant ships have one.

Careful with that dictionary, Eugene (esp in Cleveland).

 

[Enoki]

You feed the hydrogen you separate into the power plant as you separate it. It's high school science, not rocket science. If you're talking about jump fuel, you carry along fuel for a second jump as water instead of as L-Hyd. That means you have a big empty tank to put the hydrogen into.

This would mean that the conversion plant has to be capable of the maximum rate of usage of the power plant in size. I would suspect that would make it quite large in capacity.

This technique would not be for ships that make single jumps, since you need the full tankage for one jump. Most ships won't need to do two consecutive jumps. Those who do would do it because such a double jump would save at least one jump. So the differenc ewould be between the hours it takes to process the water vs. the time it takes to make a whole extra jump (or more).

That kind of jumps is certainly not going to be common. But it would be an option for the rare situations where it would be an advantage (such as rift-crossing).

So, for the one jump ship it is a worthless technique. You simply refuel off the world or a gas giant and fill your tanks that way.
For the rare situation where you need to make two jumps wouldn't it just be easier and cheaper to use drop tanks or a cargo bay tank temporary installation to achieve this rather than include a dedicated, but rarely needed, system?

The power plant fuel type of savings would be useful for almost all ships, of course.
Hans

Where does the power plant fuel cost savings come in? You have to have the same amount of fuel regardless. You have to convert the water to hydrogen using a specialized plant.

In my view a more robust fuel filtration plant capable of breaking down simple compounds, mostly gasses, like CH4, NH3, etc., along with H2O would be more valuable. You can refuel from a wide variety of sources, have no extra tankage that is rarely useful and, over all, it just makes more sense.

 

[rancke]

No numbers to back your business argument?

If you have the ability to figure out that a bigger investment for the same return is a worse deal, none are needed; if you don't, none will suffice to convince you.

It's called a fuel purification plant in Traveller...

A fuel purifier plant is capable of purifying gas giant atmosphere and seawater into liquid hydrogen. You don't need that to separate pure water into hydrogen and oxygen at room temperature.

Careful with that dictionary, Eugene (esp in Cleveland).

I shall treat that remark with all the respect it deserves.


Hans

 

[rancke]

This would mean that the conversion plant has to be capable of the maximum rate of usage of the power plant in size. I would suspect that would make it quite large in capacity.

I would suspect otherwise. A water tank, some piping and valves, a source of electricity. As I said, it's not rocket science.

So, for the one jump ship it is a worthless technique. You simply refuel off the world or a gas giant and fill your tanks that way.

It's superfluous for jumps that take the ship through any place with a source of fuel (I should have thought that would go without saying). That's why I've been talking about jumps through waypoints without a source of fuel.

For the rare situation where you need to make two jumps wouldn't it just be easier and cheaper to use drop tanks...

Perhaps, if you've invented drop tanks.

...or a cargo bay tank temporary installation to achieve this rather than include a dedicated, but rarely needed, system?

The dedication would be tied to the route. The ships that didn't travel along the route would never need it and consequently wouldn't have it. The ships that did travel along the route would need it all the time and consequently would have it.

Where does the power plant fuel cost savings come in? You have to have the same amount of fuel regardless. You have to convert the water to hydrogen using a specialized plant.

You save on volume, as I indicated in earlier posts. Say you have a ship that has to make two jumps adding up to seven parsecs. Such a ship would use practically every bit of its tonnage on drives and fuel tanks, and bridge and crew accomodation, leaving perhaps a couple of tons worth of cargo space. If it carried the fuel for the second jump in the form of water, it could have 20T of cargo space, thus being ten times as profitable.

Or you could have a courier that needed to make two jump-4. It wouldn't be possible at all. With the fuel for the second jump carried as water, it would be possible. That an improvement of infinity percent.

In my view a more robust fuel filtration plant capable of breaking down simple compounds, mostly gasses, like CH4, NH3, etc., along with H2O would be more valuable. You can refuel from a wide variety of sources, have no extra tankage that is rarely useful and, over all, it just makes more sense.

That would only be valuable if you foresee needing to be able to refuel from a wide variety of sources. If all you need is to buy some reasonably pure water from the two worlds at the endpoints of your route, a fuel purifier would just be taking up cargo space, making no sense at all.


Hans

 

[Dragoner]

none are needed.....

So you haven't run the numbers...

A fuel purifier plant ... You don't need that ....

...and this is why, because all the profits you imagine go out the window. Not to mention that pesky 1 in 12 misjump, losing a whole crew, ship and cargo; that would be hilarious to show on a Income Statement: Ship Expense- Misjump.

Talk about wiping out your bottom line.

 

[atpollard]

So you haven't run the numbers...



...and this is why, because all the profits you imagine go out the window. Not to mention that pesky 1 in 12 misjump, losing a whole crew, ship and cargo; that would be hilarious to show on a Income Statement: Ship Expense- Misjump.

Talk about wiping out your bottom line.

Foul. Bad Form.
The issue is storing fuel as Liquid Hydrogen vs Distilled Water.
No misjump for unrefined fuel is applicable.

 

[rancke]

Foul. Bad Form.
The issue is storing fuel as Liquid Hydrogen vs Distilled Water.
No misjump for unrefined fuel is applicable.

More than that. It's the issue of storing jump fuel as liquid hydrogen vs. storing power plant fuel as distilled water.


Hans

 

[atpollard]

I would suspect otherwise. A water tank, some piping and valves, a source of electricity. As I said, it's not rocket science.

While I like water as fuel from a fuel density standpoint, it will still need to be liquified for jump fuel or the tank to store H2 gas will be massive. No simple room temperature electrolysis.

[EDIT: OK, I am up to speed now. See my next comment.]

 

[rancke]

While I like water as fuel from a fuel density standpoint, it will still need to be liquified for jump fuel or the tank to store H2 gas will be massive. No simple room temperature electrolysis.

True. It's two different cases. Hydrogen for power plant consumption is one case. Liquid hydrogen for jump drive consumption is another case. For power plant hydrogen you need to separate water into oxygen and hydrogen. For refining gas giant atmosphere or seawater into jump fuel you need to filter out the impurities and reduce the temperature of the hydrogen drastically. For the latter, you need a fuel purifier plant. For the former, you don't.


Hans

 

[atpollard]

More than that. It's the issue of storing jump fuel as liquid hydrogen vs. storing power plant fuel as distilled water.
Hans

Then the volume savings will be trivial (as a percent of the ship) will they not?

Personally, I'd like to see an external bladder that stores the LH2 until just before jump, like a drop tank, and then deflates as the fuel is consumed (like dropping the tank). This allows you to 'drop' your tank AND take it with you.

Now all LH2 can be stored as H2O.

 

[Dragoner]

The issue is storing fuel as Liquid Hydrogen vs Distilled Water.
No misjump for unrefined fuel is applicable.

It is if you don't have a purification plant, those are the rules.

What has happened here is that one simple number has become misleading and after looking at various numbers like Aramis' calcs and various miscellaneous factors, the actual data doesn't bear out the hypothesis.

 

[rancke]

Then the volume savings will be trivial (as a percent of the ship) will they not?

Depends on what you think is trivial. Surely there must be some merchants who believe that every little bit added to what you've already got makes just a little bit more.


Hans

 

[rancke]

It is if you don't have a purification plant, those are the rules.

If you're just trying to prove what the rules say, there's no controversy and this argument is not so much trivial as pointless. If you're trying to refute my claims[*], using the rules as proof is begging the question.

Incidentally, I'm pretty sure the rules don't say that you get a misjump if you use unrefined fuel for the power plant alone and refined fuel for the jump drive. The rules simply don't cover that eventuality.

[*] Which specifically include the caveat: "Note that I'm not saying that the canonical shipbuilding rules don't imply that there's some reason why using water for storage doesn't work. There's just no plausible reason known why this would be the case."​

What has happened here is that one simple number has become misleading and after looking at various numbers like Aramis' calcs and various miscellaneous factors, the actual data doesn't bear out the hypothesis.

I can't make heads or tails of Aramis' numbers. I've been told that water carries hydrogen at approximately 1.5 times the same volume of L-Hyd. That works out at a saving (in volume) of roughly 33%.


Hans

 

[aramis]

True. It's two different cases. Hydrogen for power plant consumption is one case. Liquid hydrogen for jump drive consumption is another case. For power plant hydrogen you need to separate water into oxygen and hydrogen. For refining gas giant atmosphere or seawater into jump fuel you need to filter out the impurities and reduce the temperature of the hydrogen drastically. For the latter, you need a fuel purifier plant. For the former, you don't.


Hans

Actually, the plants and/or fuel scoops include sufficient processing to work as unrefined fuel for both PP and JD; they must, therefore include electrolysis or catalytic liberation of hydrogen from both water and either methane (CH4) or ammonia (NH3). So FPP's must be doing something more than simple electrolysis and/or catalytic cracking.

Plus, the FPP has a minimum tonnage of 3 Td... electrolytic systems are obviously not that minimum, since it's possible NOW to get a few liters per hour throughput in an electrolysis unit under a kiloliter...

(It's also NOT 1/12 misjump for unrefined, it's 1/36. In CT, that's a true misjump; in later editions, it's not always even a misjump, but sometimes just other jump abnormalities.)

 

[rancke]

Actually, the plants and/or fuel scoops include sufficient processing to work as unrefined fuel for both PP and JD; they must, therefore include electrolysis or catalytic liberation of hydrogen from both water and either methane (CH4) or ammonia (NH3). So FPP's must be doing something more than simple electrolysis and/or catalytic cracking.

I don't doubt it for a moment. What I doubt is that you actually need a fully functional 3T+ fuel purifier plant to crack ordinary tap water whatever the RAW says.


Hans

 

[aramis]

I don't doubt it for a moment. What I doubt is that you actually need a fully functional 3T+ fuel purifier plant to crack ordinary tap water whatever the RAW says.


Hans

The rules don't require the FPP to crack tap water, merely to refine it sufficiently to allow a jump drive to work reliably. I suspect that involves a very specific ratios of protium, deuterium, and tritium.

Power plants don't give a whit.

 

[McPerth]

Incidentally, I'm pretty sure the rules don't say that you get a misjump if you use unrefined fuel for the power plant alone and refined fuel for the jump drive. The rules simply don't cover that eventuality.

AFAIK, rules don't discriminate among PP fuel and jump fuel (at least when PP is a fusion one). I guess they assume that,being Hydrogen in both cases, there's no need for separate fuel tanks.

By inferring form the rules (not explicited on them, AFAIK), in CT and MGT(not applied in MT, not sure about other versions), the fact that you need a PP at least equal (in power) to your JD means (or so I understand) that JD is PP dependent, so using unrefined fuel for your PP, as far as may make your PP to go erratically or outright malfunction, may affect your jump capability, so leading to a missjump.

 

[atpollard]

It is if you don't have a purification plant, those are the rules.

Misjumps only happen if you use unrefined fuel in the JUMP DRIVE. The power plant can run on unrefined fuel just fine.

However, the Refined vs Unrefined issue is a straw man.
I can store refined LH2 as water, crack it to separate the H2 from the O2 and safely use the H2 as refined fuel in the jump drive. The question is will my ship save money and carry more cargo, or will it cost more than it saves and take up more room than a simple LH2 fuel tank?

What has happened here is that one simple number has become misleading and after looking at various numbers like Aramis' calcs and various miscellaneous factors, the actual data doesn't bear out the hypothesis.

Aramis did an excellent job of analyzing the use of a Fuel Purifier and Unrefined fuel stored as water and determined that 15 tons of PP fuel was the minimum necessary to save money using unrefined water and a Purifier Plant (3 dTon minimum size and TL 15).

Hans appears to be looking at simply storing the refined LH2 as Refined water and cracking it as needed ...


If I pump 140 cubic meters (about 10 displacement tons) of REFINED liquid hydrogen (LH2) into an empty 10 ton tank fuel tank, then it will fill it and I can use that REFINED fuel to safely power a Jump Drive. This is what is normally done in Traveller.

If I first pump 52.6 cubic meters (about 4 displacement tons) of pure liquid oxygen (LOX) into the 140 cubic meter tank and then add 140 cubic meters of refined LH2, I get an explosion.

Ok, so lets assume that I install a black box that can both crack water into H2 and O2 using electricity AND safely combine refined LH2 and LOX to form refined Water (H2O). Now we can combine 52.6 cubic meters of pure LOX and 140 cubic meters of Refined LH2 to form 84.6 cubic meters (about 6 displacement tons) of water. The black box can slowly extract 140 cubic meters of Refined LH2 from the refined water to power the Fusion Power Plant and store the excess LOX in the fuel tank

However, I no longer need a 140 cubic meters (10 dTon) fuel tank. What I need is a 84.6 cubic meters (6 dTon) fuel tank. In addition, the tank no longer needs to be designed to contain the super-cryogenic, maximum corrosive Liquid Hydrogen, but rather the mildly cryogenic Liquid Oxygen and room temperature liquid water. A floating common bulkhead or membrane bladder inside the tank separates the water from the pure LOX waiting for the tank to be refilled.

If one is prepared to vent the excess O2 to space, then the portion of the black box that combined molecular oxygen with refined LH2 to create refined water (no impurities) can be moved from the ship to the starport which could offer Fuel in the form of either Refined LH2 or Refined Water. This simplifies the ship's systems to a plastic water bottle for 'fuel' and a 0.07 dT box wired to crack the refined H2 from the water using electrolysis.

All of this applies to the PP fuel and excess jump fuel only, since the JD needs someplace to store the LH2 so it can use it all quickly making the hole to jumpspace.

 

[Dragoner]

Misjumps only happen if you use unrefined fuel in the JUMP DRIVE. The power plant can run on unrefined fuel just fine.

However, the Refined vs Unrefined issue is a straw man.
I can store refined LH2 as water, crack it to separate the H2 from the O2 and safely use the H2 as refined fuel in the jump drive. The question is will my ship save money and carry more cargo, or will it cost more than it saves and take up more room than a simple LH2 fuel tank?


Aramis did an excellent job of analyzing the use of a Fuel Purifier and Unrefined fuel stored as water and determined that 15 tons of PP fuel was the minimum necessary to save money using unrefined water and a Purifier Plant (3 dTon minimum size and TL 15).

Hans appears to be looking at simply storing the refined LH2 as Refined water and cracking it as needed ...


If I pump 140 cubic meters (about 10 displacement tons) of REFINED liquid hydrogen (LH2) into an empty 10 ton tank fuel tank, then it will fill it and I can use that REFINED fuel to safely power a Jump Drive. This is what is normally done in Traveller.

If I first pump 52.6 cubic meters (about 4 displacement tons) of pure liquid oxygen (LOX) into the 140 cubic meter tank and then add 140 cubic meters of refined LH2, I get an explosion.

Ok, so lets assume that I install a black box that can both crack water into H2 and O2 using electricity AND safely combine refined LH2 and LOX to form refined Water (H2O). Now we can combine 52.6 cubic meters of pure LOX and 140 cubic meters of Refined LH2 to form 84.6 cubic meters (about 6 displacement tons) of water. The black box can slowly extract 140 cubic meters of Refined LH2 from the refined water to power the Fusion Power Plant and store the excess LOX in the fuel tank

However, I no longer need a 140 cubic meters (10 dTon) fuel tank. What I need is a 84.6 cubic meters (6 dTon) fuel tank. In addition, the tank no longer needs to be designed to contain the super-cryogenic, maximum corrosive Liquid Hydrogen, but rather the mildly cryogenic Liquid Oxygen and room temperature liquid water. A floating common bulkhead or membrane bladder inside the tank separates the water from the pure LOX waiting for the tank to be refilled.

If one is prepared to vent the excess O2 to space, then the portion of the black box that combined molecular oxygen with refined LH2 to create refined water (no impurities) can be moved from the ship to the starport which could offer Fuel in the form of either Refined LH2 or Refined Water. This simplifies the ship's systems to a plastic water bottle for 'fuel' and a 0.07 dT box wired to crack the refined H2 from the water using electrolysis.

All of this applies to the PP fuel and excess jump fuel only, since the JD needs someplace to store the LH2 so it can use it all quickly making the hole to jumpspace.

I have no argument with your numbers, however, I do have some citations.

1) Everything must be done in game terms, much of it is a game device for sure, but then again the Free Trader and Speculative Market model for economics are game devices as well, because they don't work otherwise. Which in the game, it does not differeciate between PP fuel and JD fuel, it only says "use of unrefined", which implies either. Without the purifier, the misjump chance is there.

2) Hans has this tendancy to say "implausible" after talking about starships, fusion power and jump drives; which are all implausible. So see #1. The reality is that deuterium would most likely be the fuel of any fusion process, which would be in heavy water and used as a slush. Water itself is best stored as a solid as with anything, you can't spill a solid, but water brings further issues, such as complexity. An implied assumtion of a starship is that every task is complex, maybe easier for higher tech, but that doesn't change the complexity of the task. So no simple water tanks, tubing, TL5, etc. . Traveller doesn't take into account pressure, water reacts differently at different pressure, boils quicker for example.

3) Oxygen is highly corrosive as well. Explosion is a layman's term, it is a chemical reaction, and yes one just burns hydrogen to create water, it is a simple process, containment shouldn't be an issue if one is also containing and shielding a fusion reaction. One reason the scientist I was speaking with said they were bring only Liquid Hydrogen to Mars was that it could be used in simple processes, such as to make water.

3) The black box falls outside the rules, it has to be a fpp.

4) It is the Jump Drive fuel tankage that I am thinking about, if you are already using the tankage, the actual rate begins to fall, so 33% doesn't become enough of a savings, if it was 300%, then of course no doubt. Critical path engineering says to eliminate steps in your flowchart, which if no fpp, no use of water and just hydrogen, saves on complexity (esp infrastructural costs outside the ship), then would it be used?