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#76 2019-10-25 22:51:03

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,239

Re: In-Situ Propellant Production, design a opensource demonstrator

MIT engineers devise system that removes carbon dioxide from the air; Researchers have created a system that can remove carbon dioxide from a stream of air

The new system can work on the gas at virtually any concentration level, even down to the roughly 400 parts per million currently found in the atmosphere. The device is essentially a large, specialized battery that absorbs carbon dioxide from the air (or other gas stream) passing over its electrodes as it is being charged up, and then releases the gas as it is being discharged. In operation, the device would simply alternate between charging and discharging, with fresh air or feed gas being blown through the system during the charging cycle, and then the pure, concentrated carbon dioxide being blown out during the discharging.

As the battery charges, an electrochemical reaction takes place at the surface of each of a stack of electrodes. These are coated with a compound called polyanthraquinone, which is composited with carbon nanotubes. In the lab, the team has proven the system can withstand at least 7,000 charging-discharging cycles, with a 30 percent loss in efficiency over that time. The researchers estimate that they can readily improve that to 20,000 to 50,000 cycles.

Deffinately workable for mars and better than other methods we have been discussing...

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#77 2019-10-26 04:24:29

tahanson43206
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Registered: 2018-04-27
Posts: 3,109

Re: In-Situ Propellant Production, design a opensource demonstrator

For SpaceNut re #76

Another great link! Bravo!

The application I see is concentration of CO2 to feed kbd512's concept for carbon nanotube structures, and other structures made of Carbon discovered in recent years.

That seems to imply (to me at least) that CO2 released by burning fossil fuels can be concentrated from the diffuse form in the atmosphere to an almost pure form of the gas for manufacturing of valuable carbon materials, thus providing the economic incentive to drive a self-reinforcing process.

Pushing carbon dioxide into the ground has always seemed to me like a wasteful exercise.

Edit: kbd512 ... Please evaluate the MIT process for possible application on a small scale by individuals as an income stream.

The Yahoo feed I saw this morning included a bullet point about Elon Musk offering to cover a roof with solar panels for less than the cost of a traditional roof. I find that claim to be hard to believe, but aside from that, it seems to offer a way to keep the rain out and to collect solar energy.

Depending upon the amount of energy produced (which would have to be less than the energy delivered by the Sun to the roof) there might be enough to drive the MIT process.  The last time I checked (probably after one of your posts) the value of pure carbon was quite high.  While the output of the MIT process would be (relatively) pure CO2, the gas should have some value as feed stock for a pure carbon extraction process.

A company could collect CO2 from small suppliers and make pure Carbon for the nanotechnology market.

This could be a way to address SpaceNut's "poverty in America" lament.

(th)

Last edited by tahanson43206 (2019-10-26 04:52:39)

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#78 2019-10-26 16:38:22

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,239

Re: In-Situ Propellant Production, design a opensource demonstrator

Reading the description of plates and material in between reminds me of Moxie only Moxie topic.

It seems they are working on a larger unit that can have applications here as well as mars.

The technique, based on passing air through a stack of charged electrochemical plates, coated with a compound called polyanthraquinonen, depending on the battery’s state of charging or discharging.

It sounds like a capacitor with how its go plates that can charge and discharge.

The process this system uses for capturing and releasing carbon dioxide “is revolutionary” he says. “All of this is at ambient conditions — there’s no need for thermal, pressure, or chemical input. It’s just these very thin sheets, with both surfaces active, that can be stacked in a box and connected to a source of electricity.”

This would be better than the very hot moxie unit which requires some pressure...

Compared to other existing carbon capture technologies, this system is quite energy efficient, using about one gigajoule of energy per ton of carbon dioxide captured, consistently. Other existing methods have energy consumption which vary between 1 to 10 gigajoules per ton, depending on the inlet carbon dioxide concentration

Of course this is the issue for mars as energy of that level means nuclear...

http://news.mit.edu/2019/mit-engineers- … e-air-1025

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#79 2019-10-27 10:11:47

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,239

Re: In-Situ Propellant Production, design a opensource demonstrator

Science has known for a while that with the energy, heat and the right catalyst we can make just about any compound from the raw sources and that making methane is no different its just mars that controls the conditions that we must work from within.

New Catalyst turns Carbon Dioxide into fuel

Imagine grabbing carbon dioxide from car exhaust pipes and other sources and turning this main greenhouse gas into fuels like natural gas or propane: a sustainability dream come true.

Changing the level of energy input and temperatures are part of the solution to a Standardization of a safe unit for commercial sales is what we have been waiting for. This gives hope to those that have wood to create a better storable for winters use. The sources for the co2 can also be from lots more than just just wood as we can pyrolyze plastics and paper as well as others to use as feed stock to the reaction.

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#80 2019-12-29 18:10:34

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,239

Re: In-Situ Propellant Production, design a opensource demonstrator

The path for fuel creation here on earth for green world plus is crossing paths with mars again... So why is there no commercial units yet?

index.php?action=dlattach;topic=49630.0;attach=1599942;image

Energy input data is on the slide...

https://www.reddit.com/r/spacex/comment … _starship/

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#81 2019-12-29 20:06:55

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,239

Re: In-Situ Propellant Production, design a opensource demonstrator

The marco polo unmanned mission which would be a precussor landing and insitu fuel processing machine seems to not be moving ahead very fast.

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#82 2019-12-30 04:01:22

kbd512
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Posts: 3,592

Re: In-Situ Propellant Production, design a opensource demonstrator

tahanson43206,

I take no issue with the various attempts to use the Sabatier reaction to produce CH4 for rocket fuel and energy storage, but thus far the R&D efforts to do that seem pretty lack-luster.  Efficient CH4 synthesis is nowhere near as advanced as water electrolysis technology used to produce H2 and substantially more complicated in operation, as the infographic SpaceNut reproduced in Post #80 illustrates.  We already have multi-megawatt reverse fuel cell H2 production plants in operation around the world in every climate imaginable and they fit inside half-length CONEX boxes.  They've been in operation for many years now and function reliably for many tens of thousands of hours without significant maintenance, or any maintenance at all in most cases, using intermittent solar and wind energy.  Oddly enough, that was how they were designed to be used from the outset and probably why they work so well.  None of that should be taken to mean that we shouldn't perfect Sabatier reactor technology to add to our suite of Mars survival tools, but it's clearly going to be an uphill-all-the-way battle.  No doubt Louis will take issue with my assessment, but I've yet to see any compact and lightweight industrial scale (multi-MW) Sabatier reactors in operation here on Earth.  That should be an indicator that there's no other demonstrated use case for such technology (industrial scale CH4 synthesis, not the Sabatier reaction), unlike water electrolysis.  As long as we have so much gas coming out of the ground that we have to flare it off every time we drill a well, that's unlikely to change until governments / academia / venture capitalists decide to develop it for Carbon-neutral fuels or making rocket fuel on Mars.

In any event, regenerative fuel cells reacting O2/H2 still outperform batteries on energy density by at least an order of magnitude and fuel cells as a general technology class are right up there with the most highly refined gas turbine designs in existence in terms of mean time between failures- something that no conventional battery technology has ever demonstrated.  I've never seen a gas turbine spool up to 100% of its rated power in less than 5 seconds, nor am I aware of any that operate most efficiently at less than maximum rated power (not the same thing as burning less fuel at significantly reduced power output; those aerodynamics and thermodynamics issues are a real PITA).  The consumable replacement parts for fuel cells are also very lightweight and compact, mostly limited to seals and membranes that can be quickly replaced by unskilled laborers using hand tools.  As an added bonus, especially given the dearth of gas stations on Mars, the fuel efficiency of a prototypical fuel cell also happens to be roughly double that of a gas turbine.  Apart from the wildly disproportionate energy density advantage provided by nuclear fission, until we can combine all of those highly desirable characteristics into a battery design, a regenerative fuel cell is the most likely candidate for conventional backup power on the scale of 100's of kW's or less.  IIRC, until your power output requirement is in the multi-MW range, no reliable combustion engines (non-race-car engines) compete in terms of power-to-weight with fuel cells (I believe the US Army determined that not even their 1MW output AGT-1500's that power their M1 tanks could compete with fuel cells in the PWR department).  Since the same units that perform the O2/H2 separating would also provide the power, we're unlikely to produce lower-mass alternatives.

Anyway, my $0.02 on that DIY CO2 capture idea for our fellow Earthlings:

So far as I know, pure Hydrogen is the only practical clean fuel with the energy density required for every conceivable use from generators to cars to rockets and pure LNH3 is the only practical way to transport or store that fuel at ambient temperatures, feasible pressures, and with volumetric Hydrogen density approaching traditional liquid hydrocarbon fuels.  In the transition period, we certainly can and should experiment with cleaner alternative fuels such as methane and propane.  Since nobody has explained to me how slowing the rate of atmospheric CO2 increase is doing anything except exacerbating the global warming problem at a slower rate, my presumption is that we actually have to stop emitting CO2 at some point- the sooner, the better according to the science.  There's no other realistic alternative if that's our goal.  After 30+ years of concerted global effort invested into every conceivable leap-ahead battery technology, miraculous new battery technologies have yet to materialize.  The dramatic cost decrease associated with Lithium-ion batteries has merely resulted in a vehicle battery that cost as much as a complete gasoline powered car, none-too-impressive in my book.  As such, it's obvious to me that Hydrogen really is that hard to beat.  All arguments about the efficiency of batteries is academic in the face of current technological reality.  We don't make enough of them to reduce manufacturing costs to the point where they're cost-competitive with combustion engines, we don't recycle them, and they're absurdly expensive for the paltry energy storage they provide.  Assuming we do come up with a Lithium-ion replacement, it'll be at least another 10 years before we've industrialized that new technology and probably another 30 years before its cost comes down to the point that the masses can afford to use it in a significant way, such as powering the vehicle they use to drive to work.

Well, where does that leave us?:

My plan is to centralize CO2 emissions sources and then collect the byproduct CO2 using purpose-built industrial scale machinery optimized to process the CO2 produced by Haber-Bosch plants into pure Carbon powder using a single-step EUV process.  Those plants would be used to create the transportable / storable LNH3 fuel required to power everything else and to provide the precursor material to CNT, which is necessary to fabricate lightweight / high-strength structures for everything from I-beams to aerospace transport vehicles.  The most logical place to end our near total reliance on Earth's finite stores of hydrocarbon fuels is as near to the source as is practical using technology we already have, rather than technology we wish we had.

We don't have anything remotely resembling like-kind replacements for Hydrogen-rich fuels or plastics, so production of gas and oil is still required.  I don't see that changing in the near future, even though we should continue to develop the technology required to synthesize fuels and plastics from atmospheric gases and water.  The fundamental difference between what we're currently doing with gas and oil and what I'm proposing is that we truly "consume" every part of those hydrocarbon molecules we extract to transform them into cleaner fuels and structural fabrication materials at the same time.  That must occur at the refinery.  It's not practical to attach a CO2 collector to every tailpipe.

There are three practical ways to "do more with less":

The first is making moving objects lighter to reduce the power required to move them.  CNT fiber is some of the lightest and toughest stuff that we actually know how to mass produce.  However, it requires high purity Carbon and very tightly controlled manufacturing processes to achieve mechanical properties that make it superior to plain Carbon Fiber.  Unfortunately, it also requires a much cheaper source of Carbon than baking Carbon-containing compounds in very high temperature ovens or digging it out of the ground and removing the impurities.  Both of those processes are extremely energy-intensive and thus very costly, ultimately impractical for supplying the quantity of Carbon required to replace the Iron and Aluminum used in today's vehicle structures.  The only practical and "already paid for" source of Carbon that I'm aware of is derived from combustion.

Simply collecting CO2 is not sufficient to produce income.  After the CO2 has been collected, you need to do something useful with it.  You're not going to sell CO2 to anyone, as anyone who needs CO2 already gets it from somewhere else as a commodity product.  The equipment required to separate Carbon from CO2 is not compact or cheap or simple to operate.  Nobody I know makes their own home brew Carbon Fiber, either.  It's the sort of thing we need corporations, maybe even governments, to implement at a scale that would make the CNT product an affordable fabrication material.  I just don't see how individuals are going to separate the Carbon or grow the tubes in their garages, even though it's possible to do it.  The videos you see on YouTube where people are growing tiny quantities of their own CNT most likely don't have the equipment required to guarantee quality control of their product unless they're working for a corporation that has already invested millions in terms of education, training, and equipment.  Apart from the energy required to split CO2, quality control is where most of that capital would be invested.  The university labs have equipment that most amateurs couldn't even begin to afford.  Massive throughput is required to make Iron and Aluminum refining a profitable endeavor and that's what I'm trying to replace at a significant scale.

The second is to increase the efficiency of the engines that power those moving objects.  Until those batteries with order-of-magnitude improvement in energy density arrive, that would mean fuel cells.  It's certainly possible to fabricate fuel cells in small machine shops, even if the knowledge to do that is somewhat specialized.  In both construction and operation, they're much simpler than combustion engines, with very few moving parts.  The catalysts and permeable membrane materials are where most of the cost comes in, but cheaper catalysts certainly would work for generators and motor vehicles.  Mass production and quality control would put a serious damper on home workshop efforts.  An engine factory that cranks out engines by the hundreds of thousands is the most likely candidate for mass production.  Since nobody casts their own engine cases or forges their own crankshafts, either, it's improbable that they'll be machining their own plates, even though anyone with a CNC mill certainly could do it for the price of the mill, knowledge required to use it, and the Aluminum or Carbon for the plates.  I could definitely see servicing performed by small shops or DIY'ers with a modicum of knowledge, much as they already do with combustion engines.

The third way is to stop treating things that should be durable goods as disposable products.  Most people think of cars as disposable products these days, but the energy and labor that went into making them is considerable and one of the best ways to reduce CO2 emissions is to stop treating so much of the material and machining efforts as disposable artifacts of modern society.  This is almost entirely down to the personal behavior of the consumer.  The reason we have so many disposable products is that consumers chose to purchase those cheaper disposable products instead of more durable but more costly products.  If there wasn't a market for such products, then nobody would make them.

Do you really need a brand new car every 3 years, or is the vehicle you have something you intend to keep serviceable as long as you can?

If you knew that 2/3rds of everything we make would end up rotting or rusting away in a landfill, where it's not serving anyone, would that change how you treat what you own and what you choose to buy?

Are you wiling to pay more for something that lasts 20 years vs 2 years and if so, how much more?

Everyone will have different answers to those questions, but when customers start voting with their wallets the manufacturers tend to pick up on that fairly quickly.

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#83 2019-12-30 07:08:17

tahanson43206
Member
Registered: 2018-04-27
Posts: 3,109

Re: In-Situ Propellant Production, design a opensource demonstrator

For kbd512 Re #82

It is an honor to find your long post addressed to me << grin >>

This is one of the better summaries I have seen of ways we humans could address climate change and various other needs, such as increasing availability of clean fuel for average consumers.

I'll tag it with climate change for now, although other tags seem appropriate.

One immediate effect of your comments here is to influence my thinking about sea based wind-to-gas plants to include the ammonia option.

The commercial advantage of making methane is ability to use existing infrastructure to distribute the product.  The customer base would consist of individuals and groups who demand non-fossil fuel for their heating and cooking applications.  The numbers of those customers can be expected to grow as the population comes to understand the consequences of staying on the course we are on.

I agree that moving to production of green methane is a tool for reducing the volume of "new" fossil fuel fed into the environment, but that is potentially a significant change in itself.  Your suggestion of moving toward Hydrogen as a fuel is supportable already, and will become more attractive over time. The use of ammonia as an energy carrier on a global scale has the distinct advantage that it is already in progress on a global scale.

The competition between methane and hydrogen seems (to me at this point) to come down to costs for infrastructure adjustment.  It is entirely possible that the advantages of Hydrogen for the long term will slowly influence designers to build the required infrastructure in new or replacement projects.

SearchTerm:ClimateChange   Author:kbd512

If (someone) can scare up the resources to tackle design of a sea-based wind-to-stored-energy system on a scale appropriate to the problem, then it would follow that teams would be assigned to develop options for methane (on one hand) and ammonia (on the other).

Because the proposal over in the power-to-gas topic is to design for the 14 Megawatt scale of existing state-of-the-art deep sea wind turbines, there would be enough energy available to consider industrial scale solutions which use high pressure vessels and high temperatures to efficiently perform decomposition of molecules from the environment and assembly of the desired energy carriers.

I like the inherent advantage of making liquids for convenience of transport, but a careful analysis might show that leaving selected gases in the form of gases would be economically competitive.  As just one example, Hydrogen could be used to fill the envelope of drone blimps for transport, and the empty shell of each blimp could be brought back to the sea-based wind-to-energy plant by sea.  The blimps would be emptied of content in properly secured facilities.

In any case, thanks for taking the time to build on your previous work to address the issues at hand.

I'll make this offer again:  If you are willing I would be willing to post your #82 here on luf.org's blog.  I think it would stand up to the review there.

As you have probably noticed, Louis made the cut.  I think you could do so as well, or at least i'm willing to recommend your work.

(th)

Last edited by tahanson43206 (2019-12-30 11:21:25)

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#84 2019-12-30 11:34:11

kbd512
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Registered: 2015-01-02
Posts: 3,592

Re: In-Situ Propellant Production, design a opensource demonstrator

tahanson43206,

Feel free to repost to your heart's content.  I'm not sure how any of what I'm saying is the least bit controversial.  If you accept the following empirically valid premises, then I'm not sure why people would come to other conclusions:

1. Global warming is an actual problem that requires practical solutions.  It doesn't matter if it affects everyone this very minute if it will eventually significantly damage the environment that future generations must live in.  I have children, as most of us do, so I care about the world I leave to them.  None of the far-fetched doomsday scenarios have to be true to validate the logic of hedging bets on how what we do now will affect the environment for future generations.  I think good examples of that logic are the various superfund sites that we, as a nation, have decided that we're willing to spend any amount of money to clean up.  We can't afford to permit the entire planet to become a superfund site.  Since we also don't seem to have any starships available to leave home for other worlds, I'm presuming that most of us will still live on Earth in another generation or two.  I can only speak for myself, but I'm not willing to bet the farm on us creating warp drive enabled starships to travel to other inhabitable planets that we haven't ruined in the next generation or two.

2. Batteries with energy densities equivalent to the same mass of liquid hydrocarbon fuels have not materialized, even in laboratories with no practical limits on what they can spend to produce a working prototype.  If it was simply a mater of money, then the hundreds of billions of dollars expended worldwide on battery tech R&D efforts should've produced something with an energy density approaching that of liquid hydrocarbon fuels.  Since that hasn't happened, we should devote more money to alternatives that do match the energy density and significantly exceed the power density of combustion engines (up to at least 1MW or so, as determined by our own military's experimentation).  I'm not in favor of stopping R&D on batteries, but I'm in favor or taking stock of where we're at and where we'd need to be to replace hydrocarbon fuels.  It's not a pretty picture, so I want to paint a new one.

3. Current fuel cells are roughly an order of magnitude more mass efficient, even though they are less energy efficient than batteries, and mass is the major driver of power requirements and therefore cost at a planet-wide scale.  Everything we use has to be moved, often over very significant distances, from where it was manufactured to where it will ultimately be used.  If we can match the energy density of liquid hydrocarbon fuels and best them on power density in most use cases, then we have a like-kind substitution and a rough doubling of energy utilization efficiency over combustion engines of any kind in most cases.  Large commercial aircraft power plants are the only cases where the physics of moving them doesn't initially favor fuel cells, but those are far lower in numbers and all aircraft use in aggregate only accounts for around 2% of CO2 emissions at a global scale.  As such, any realistic plan to address global warming should focus in on those 98% use cases.

4. Apart from energy efficiency, the other very important aspect to the physics and therefore economics of moving something from Point A to Point B is structural mass.  This is where advanced high-strength / low-density fibers and plastics come into play.  If we can combine a rough doubling of energy utilization efficiency with at least a rough tripling of weight reduction over metals, then we have something that is qualitatively "better" in all aspects affecting energy economy when compared to what we're currently using.  If the same production process that creates the fuel also produces the precursor for this new "best in class" structural material, that's a very fortuitous and happy coincidence that represents a synergy in production processes.

5. The only Carbon-free fuel that can be stored as a liquid at room temperature, under manageable pressures, is anhydrous ammonia.  LNH3 product will be transported and stored in bulk quantities at service stations, whereupon its Hydrogen will be extracted at the pump using plasma crackers and the Nitrogen exhausted back into the atmosphere it was originally extracted from, and then pumped into high pressure H2 tanks made from our new CNT composite structural materials.

The entire point of this exercise is to replicate the existing energy transport and distribution infrastructure for everything that moves or provides backup power, this time without injecting massive quantities of CO2 into the atmosphere.  It requires no revolutionary leap-ahead technologies, no improvements over existing technology in energy or power density, and uses existing extraction and capture processes.  It does require scaling out of those processes, but we already know how to do this because it's no different than the infrastructure we're already using for agriculture.  The fuel cell technologies are already in use in many metropolitan buses and trains.  This approach can actually work because it doesn't require new technology that doesn't actually exist.

If there are other seriously scalable approaches that don't require massive new infrastructure programs or technologies that simply don't exist, then I'm unaware of what those approaches entail.  I've done quite a bit of review work to see what else is available and practical, but nothing else gives me a "warm fuzzy" about a wholesale approach to solving our global warming problem.  Putting batteries we don't recycle into absolutely everything, banning airplanes, and killing all the cows is just lunacy from "green religion" fanatics (I'd call them heretics to their own cause) and needs to be pointed out as such by everyone with rudimentary mathematical abilities and plain old uncommon sense.

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#85 2019-12-30 12:41:17

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,239

Re: In-Situ Propellant Production, design a opensource demonstrator

Amonia fuel cell nitrogen concentration release is it at a level that will cause occupant of a vehicle to have breathing dificulty as its used? We have trouble now with smog created by vehicles and wonder under the same levels of traffic would we not have a simular condition but with nitrogen concentrations.

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#86 2019-12-30 12:42:15

tahanson43206
Member
Registered: 2018-04-27
Posts: 3,109

Re: In-Situ Propellant Production, design a opensource demonstrator

For kbd512 re Permission to Repost #82

Thank you for your approval.  You may check out the posting here: https://luf.org/2019/12/30/climate-change-fuel-options/

If you wish to request changes please do not hesitate to let me know.

luf.org, like NewMars forum, draws readers from around the world.

I am hoping to encourage more cross-site correspondence.  We have already received contributions from Lizard King on finances and related matters.

Your contribution may stimulate someone else to respond.

For luf.org readers/members who find this post, please be aware that NewMars.com/forum has a VERY liberal registration policy.

Almost ANYONE can gain registered status, as the large number of spam providers confirms.

However, occasionally the registration software blocks a person we would LIKE to have join.  The clue is that you do NOT receive the confirmation email promptly from the registration software.   If you do not receive the temporary password within 24 hours, the ID you tried is blocked for some reason.

You can deal with that after you get registered. Just try another ID until you receive the confirmation email.

If THAT doesn't work the problem may have to do with your email provider.  Try another email provider.

Please document ALL problems and report them when you finally secure access.

***
For SpaceNut ... the recovery option appears to have been removed.  Has anyone notified you of the change?

(th)

Last edited by tahanson43206 (2019-12-30 12:54:32)

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#87 2019-12-30 15:42:27

kbd512
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Registered: 2015-01-02
Posts: 3,592

Re: In-Situ Propellant Production, design a opensource demonstrator

SpaceNut,

I'm not talking about directly pumping LNH3 into passenger vehicles.  Toyota has LNH3 plasma crackers / pure H2 gas dispensing stations in Japan and California as I write this.  Their plasma cracker technology produces ultra high purity H2 form LNH3, meaning 99.999%+ purity.  I wrote about this in another thread and provided links.  I believe this technology stemmed from a joint venture between Gifu University, the Japanese government, and Toyota.

The H2 is first separated from LNH3 by the plasma cracker at the gas pump and then pressurized as it's fed into the Mirai's 10,000psi Carbon Fiber composite tanks.  The 5kg of stored H2 is sufficient to propel a small SUV more than 310 miles.  I believe the combined weight of the H2 tanks is 87.5kg.  IIRC, the 114kW fuel cell system weighs 57kg, or 2kW/kg.  The shoebox-sized 100kW H2 fuel cells from that British company I mentioned in that other thread are 3kW/kg, made possible merely by the reduction in plumbing and pumping that comes from recirculating the H2O byproduct to cool the fuel cell.  That cell is standard Aluminum construction in all other respects, meaning nothing special.  Mirai's total system weight with fuel, less drive train, is around 350 lbs.  That's right inline with a very advanced all-Aluminum and plastic 4 cylinder turbocharged gasoline engine.  The drive train components are lighter than traditional transmissions and ancillary power transfer equipment.  Curb weight is around 4,000 lbs, which is nearly identical to our Cadillac XT5 which weighs in around 4,100 lbs.

Feel free to ignore this rant about engine weight and cost...

You can certainly make 4 bangers substantially lighter if you don't care about longevity.  Yamaha's 150hp Apex snow mobile engine is around 120 pounds in dry weight, but you're going to replace components on a regular basis with revs to 10,000rpm+ and its fuel economy is more inline with aircraft engines than modern car engines.  That's not necessarily a bad thing since the components are relatively small and inexpensive, but it's not a 100,000 mile engine and would never pass state emissions tests.  IIRC, the people working on this in the experimental aviation world seem to agree it's realistically a 1,000hr TBO engine, no different than modern 2-strokes.  After that period of time, you're going to tear it apart, inspect it, and replace nearly everything that moves, just like any other aircraft engine.  The fuel and overhaul costs make them cost competitive with traditional large displacement low-RPM aircraft engines from Continental and Lycoming, but only just.  No support from the manufacturer will ever be forthcoming, either.  I attempted to acquire one of these engines for my homebuilt aircraft last year.  The amount of money I was going to ultimately spend on the complete installation ($25K) would've been equal to or greater than a certified aircraft engine with the same horsepower, fuel economy was no better, and it required 93 Octane vs 87 Octane MOGAS (not the same thing as pump gas).  Turns out that there are no free lunches to be had in the aviation world- reliable liquid cooling systems, purpose built EI + EFI + engine monitoring, and gear boxes with actual torsional vibration testing are crazy expensive.  If you demand quality, you're going to pay dearly for it.  The Apex's firewall forward weight was around 100 pounds less than the 150hp Continental O-300D that I'm currently building, which was a highly desirable advantage.  I also looked into Mazda wankel engines as well, but the builder who actually owns a Mazda parts shop out in WA state and has one installed and flying on a routine basis in his homebuilt Vans RV quoted a nearly identical price for a nearly identical power output engine.  His firewall forward solution was even heavier than my O-300.

After 2 failed attempts to acquire an Apex engine through eBay I gave up, accepted the lesson there, and then acquired most of the major bottom end components through eBay from various aircraft engine parts salvage operations.  I have my crankcase, oil pan, and crankshaft cleaned up and they're going into the repair stations used by the certificated world (DivCo and Aircraft Specialties) very soon.  My gears, camshaft, and connecting rods already yellow tagged (released from maintenance as serviceable parts).  All told, around $6K worth of parts with another $3K to $4K worth of repair work.  Once that's done, the 6 aftermarket jugs and pistons from Superior Air Parts will set me back another $6K.  The mags and throttle body injector (poor man's fuel injection) will run another $4K.  I have no idea what the custom engine mount will cost after I submit the CAD files to Acorn, but I'm guessing it'll be at least $3K if not $5K.  The wooden prop is only around $1K, which is nice.  The custom intake and exhaust will run around $1K each.  At the end of the day, I'll have some small peace of mind that all these critical parts have been professionally inspected and repaired or fabricated, for whatever little that's actually worth.

I purchased the oil pan and accessory case used in the Continental IO-360 because the bolt pattern is the same (the IO-360 crankcase is a slightly beefed up O-300 crankcase design) and the pan is Aluminum alloy instead of the O-300's Magnesium alloy that nobody will repair ($250 for a brand new part vs $1,000+ for something that looks like it's been through the last world war).  Unfortunately, this necessitates a custom intake manifold since the intake no longer goes through the oil pan (a truly crap-tastic design with unequal length runners), but I finally found someone willing to do this sort of work and he's been fabricating custom parts in his machine shop for longer than I've been alive.  My crankshaft is also an IO-360 crankshaft because Continental quit making O-300 specific crankshafts and now uses the IO-360 crankshafts on O-300's.  That was an absolute PITA to figure out, until I finally spoke with someone at Aircraft Specialties who knew the answer.

Anyway, sorry for going off on a tangent there...  Now back to fuel cells vs combustion engines.

The Cadillac XT5's LTG engine has a dry weight in the 330 pound range.  The dry weight of the 4L65E is around 120 pounds.  Highway range is around 490 miles with 116 pounds of 87 Octane gasoline.  Since we still have another 216 pounds to play with, we could easily match the weight and range of the LTG/4L combination to produce equivalent range and power output, if that's desirable.  The vehicle form factor might have to change to accommodate slightly larger H2 tanks, but that's only a matter of engineering.

The power to pressurize the H2 comes from the combination of grid electricity and from solar panels mounted to the roof of the gas stations.  That is how they manage to transport and store H2 at higher volumetric Hydrogen density than Liquid Hydrogen.  In practice, this means that Hydrogen reacted in a fuel cell contains approximately equivalent energy content to liquid hydrocarbon fuels for purposes of fueling prime movers used in transport.

I'm not sure why you think releasing Nitrogen back into the atmosphere would create more smog than combusting hydrocarbon fuels, but whatever smog is created would be significantly less than that created from internal combustion engines that are no more than half as efficient as H2 fuel cells.  There will be some nitrous oxides generated during the reaction in the fuel cell because Nitrogen is naturally present in Earth's atmosphere and a tiny quantity of N2 reacts with the O2 being reacted with the H2, but in significantly lower quantities than what we get from combustion engines.  In any event, emissions issues pertaining to the use of fuel cells have already been fairly extensively studied by researchers and I've never read a paper positing that emissions from fuel cells would be greater than combustion engines.

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#88 2019-12-30 16:04:18

SpaceNut
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Re: In-Situ Propellant Production, design a opensource demonstrator

I seemed to remember that the cracking unit was on the vehicle but could be wrong as we cover so much ground in the topics which covered how to contain hydrogen and what was the better carrier.
Power to Ammonia for Energy Storage
Autonomous Passenger Carrying Electric Aircraft
Fuel Cell Development, Application, Prospects
which ends up usually at Power to gas is the way forward for storage

For mars the use of nitrogen as a carrier component of fuel creation its not as readily available for use. Which makes it problematic until there is a surplus of it being generated.

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#89 2019-12-30 17:09:49

kbd512
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Re: In-Situ Propellant Production, design a opensource demonstrator

SpaceNut,

On Mars I think we'd simply electrolyze water and pay the piper for the compression costs, in terms of electrical energy input, required to store the O2/H2 gases produced.  I don't believe there's a limit to the number of times we can recycle the water byproduct, so once we've acquired a single H2O charge to store however much power we think we need to store, only periodic "topping off" is required.  We can take purified water with us and then split the reactants after the ship arrives on the surface.

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#90 2019-12-30 17:29:36

SpaceNut
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Re: In-Situ Propellant Production, design a opensource demonstrator

Its the added mass of launch to mars that costly and why we are doing insitu processing in the first place to make fuel from mars and not bringing it from earth as we are not able to land the tonnage that a ship will require to get back off from its surface.

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#91 2019-12-30 17:55:00

kbd512
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Re: In-Situ Propellant Production, design a opensource demonstrator

SpaceNut,

Fuel cells still beat batteries if energy density, longevity, and field repair / refurbishment matter.  For the power requirements we're considering for ISPP, I say it does.  Others are free to disagree.  NASA has a long history of developing man-rated fuel cells for space flight applications, so it's within their institutionalized knowledge base, just like solar panels and batteries.  If we need to store power in batteries, then the tonnage of batteries required starts getting crazy when the power requirements range into the 100's of MWh's.  We have a fixed time table for returning to Earth, so we can't afford any downtime.  Every last bit of energy we collect has to be used or stored for later use.  I think a fuel cell is also a good option to even out power input to the ISPP plant.  Power fluctuations measured in megawatts from an oversized solar array won't agree well with continuous process equipment like a Sabatier reactor.  I really do think some manner of stable base power needs to be established.  If others here are so opposed to nuclear reactors, then we don't have a lot of other practical options that can provide the kind of stable input power this process demands.

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#92 2019-12-30 19:55:02

SpaceNut
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Re: In-Situ Propellant Production, design a opensource demonstrator

Lets work out the benefits of high pressure hydrogen and long term storage on mars is sending a means to make a composite tank on mars to hold it and not smelting of metals to make the tank to hold it. The Hydrogen can be stored physically as gas typically in a high-pressure tanks at 350–700 bar or 5,000–10,000 psi tank pressure. Storing 1 kg of hydrogen at 100 kPa and 25°C requires a tank of volume 12.3 m3. Compressing hydrogen to 350 bars decreases the required storage volume by 99.6%.

http://www.hydrogenmaterialssearch.govtools.us/

https://www.energy.gov/eere/fuelcells/hydrogen-storage

fcto_storage_fuel_density.png?itok=cEGlqiC9

https://www.hydrogen.energy.gov/pdfs/re … 2013_o.pdf
Development of High Pressure Hydrogen Storage Tank for Storage and Gaseous Truck Delivery

https://www.nrel.gov/docs/fy02osti/32405b27.pdf
Hydrogen Composite Tank Program

For the rocket we would need to move the high pressure by reducing the temperature of storage before fueling up the ship so tha the amount of storage volume of liquid hydrogen is as small as it can get. Liquid requires cryogenic temperatures because the boiling point of hydrogen at one atmosphere pressure is −252.8°C

We will also want to do the same for the oxygen process as well as it save energy until the time to launch the ship is required.

https://www.mahytec.com/en/products/com … n-storage/

Making a landed ship have less mass for landing means making a strap on sort of drop tank for sending the ship home after making all the fuel to go home.

Something else to think of is that the tank making equipment can double as habitat chamber making for crews to live in.

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#93 2019-12-30 20:33:48

tahanson43206
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Re: In-Situ Propellant Production, design a opensource demonstrator

For SpaceNut re #92

Thank you for the infograph (a term I'm picking up from kbd512) comparing various fuels (liquid and various pressure gas forms).

I followed the Storage Tank link and followed the manufacturer's summary of their progress in meeting DOE goals for hydrogen storage for shipment.

This topic is not the right place for what I am looking for, which is a way of evaluating the use of lifting property of Hydrogen at 1 bar to ship the gas via blimp. The question that occurs to me is what compression is feasible (a) and (b) cost effective for a blimp shipment method.

The pdf from the manufacturer of hydrogen shipping containers estimated 90% throughput for a shipment using their equipment.

Is that a figure that would work for a blimp transport system?

The Earth's winds could be enlisted to move blimp Hydrogen transports from the point of manufacture to a destination, if enough time is available before losses exceed acceptable levels.

(th)

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#94 2019-12-30 23:33:10

kbd512
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Re: In-Situ Propellant Production, design a opensource demonstrator

SpaceNut,

We don't need or want (my contention) high pressure gaseous H2 for delivery to refueling stations.  At room temperature, liquid NH3 pressurized to 114 psi, or thereabouts, contains more H2, by volume, than pure liquid H2.  Incidentally, the big rig that delivers the LNH3 to the refueling stations has tires that are most likely pressurized to around 110 psi if they're properly inflated.  That's what I meant by manageable pressures.

There is no compelling reason to go any further than that down the technological rabbit hole of greater volumetric H2 storage density because it simply doesn't get much better than LH2 when the practicality of the solution is taken into account.  We absolutely must stick to practical existing technologies.  We have plenty of N2 in our atmosphere, we have plenty of H2 from CH4, Haber-Bosch works quite well, and that process provides plenty of leftover CO2 to transform into Carbon Fiber or Carbon NanoTube fabrics for composites or fiber filled plastics or wiring needed for future vehicular structural applications to produce stronger yet lighter and more durable structures than metals will ever allow for.

We can get everything we need to build a CO2-free energy infrastructure using what we already use for other purposes.  No magical new technologies should even be considered.  This is about getting stuff done, not satisfying the endless curiosity of scientists too busy playing with their expensive new toys or scaring the kiddies with doomsday prophesies to recognize the fact that some of us here are more interested in actually solving the problem, rather than just talking a good game about using cleaner forms of energy.  So long as there's an almighty dollar to be made, we can always count on someone who's willing to do whatever it takes to make it.

There's no way in hell we're going cold turkey off of fossil fuels, because if we're honest with ourselves we're not within a country mile of that goal, so oil companies need not lobby to stop anything.  Their product will still be in just as high demand as it ever was, but more people will get to benefit from it and there won't be nearly as much in the way of unwanted byproducts from using it.  The solution doesn't have to be perfect, nor must it satisfy the religious beliefs of the heretical high priests and priestesses of climate change to be better than what we're presently doing.  More jobs will be created scaling out the required infrastructure and making new cars.  We'll have Ford / GM / Chrysler make trucks with greater aesthetic appeal than Tesla's DeLorean-esqe abortion so people will actually want to buy them.  We can also do another cash-for-clunkers program to cull the existing fleet of combustion engine powered vehicles.  They don't need to drive themselves, fly if you put wings on them, or any other such nonsense.  They just need to be built like brick outhouses using tougher-than-sheet-steel fiber filled plastics and composites that deform rather than dent and don't rust.  BMW already proved that was the way to go and the insurance companies agreed so they lowered rates on their CFRP bodywork EV's, which are far less laborious to replace than repair of equivalent sheet metal bodywork.

For Earth-bound passenger vehicles, 700 bar gaseous H2 storage tanks are a real thing, they've been crash tested to our government's satisfaction, and constructed with a safety margin of a factor of 2 or more (I don't recall what the exact number is, but I know it's at least 2 for the Mirai's H2 tanks; IIRC, they're designed to turn into Carbon spaghetti rather than fragments if they rupture- still dangerous, but not as dangerous as some have made them out to be).  In all practical use cases, the weight is a wash between combustion engines and fuel cells or it slightly favors fuel cells- especially in terms of ongoing maintenance costs.  Apart from the initial startup costs associated with kick-starting the transition, which we can afford to write off for both ourselves and the rest of the world- one of the benefits of holding the world's reserve currency, the rest is gravy.

For Mars bases, the power infrastructure isn't going anywhere, much like military bases here on Earth.  Spectacular volumetric and gravimetric energy densities aren't required, just something around an order of magnitude better than the best batteries in existence, which is completely doable with regenerative fuel cells plus solar panels and right in line with hydrocarbon fuels used in internal combustion engines.  For vehicles, it might make more sense to use some combination of batteries, super capacitors, and/or fuel cells.  I think it'd really depend on the use case.

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#95 2019-12-31 09:40:21

SpaceNut
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Re: In-Situ Propellant Production, design a opensource demonstrator

Applications are the dictator for storage volume...

http://www.airproducts.com/Products/Gas … rogen.aspx

https://h2tools.org/hyarc/calculator-to … calculator

BFR is for starship 1,100,000 kg and the volume at liquid 1 atm is 548,703 ft3 or 15,537.5387 m3

https://www.asknumbers.com/cubic-feet-t … eters.aspx

if the bfr starship is a 10m tank diameter how tall is the tank?
https://www.sensorsone.com/length-and-d … alculator/

https://www.calculatorsoup.com/calculat … n/tank.php

10 x 100m long is 7,854 m3 which is half of liquid h2 for starships tank size

https://ntrs.nasa.gov/archive/nasa/casi … 001808.pdf

http://canada.marssociety.org/winnipeg/ … esting.doc

The ability to make Basalt tanks has been answered for mars
Basalt fiber

Compact and Lightweight Sabatier Reactor for Carbon

http://www.digipac.ca/chemical/mtom/con … batier.htm
http://www.digipac.ca/chemical/mtom/con … atier2.htm

http://www.pennenergy.com/articles/penn … ction.html

We know the process and the work that nasa is doing to lower the power, pressure and heat of reaction but for all its worth there is not COTS vendors to which we can send.

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#96 2020-01-01 22:02:25

SpaceNut
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Re: In-Situ Propellant Production, design a opensource demonstrator

updating topic

tahanson43206 wrote:

For SpaceNut re #721 and references to scroll pump ...

The link you provided to the NASA site came up with a powerpoint dated 2017, with a number of references to work by Dr. Zubrin and associates.

The technology of a "scroll pump" is new to me.  Someone might be interested in the page at Wikipedia:

https://en.wikipedia.org/wiki/Scroll_compressor

In the NASA powerpoint, only two stages of compression are shown, moving from Mars atmosphere to input to the Sabatier reaction.

(th)

RobertDyck wrote:

NASA SBIR - 1998 (abstract only): Mars Atmospheric Carbon Dioxide Freezer

NASA Technical Report Server (NTRS) - 2012: Mars In Situ Resource Utilization Technology Evaluation

We have examined the technologies required to enable Mars In-Situ Resource Utilization
(ISRU) because our understanding of Mars resources has changed significantly in the last
five years as a result of recent robotic missions to the red planet. Two major developments,
(1) confirmation of the presence of near-surface water in the form of ice in very large
amounts at high latitudes by the Phoenix Lander and (2) the likely existence of water at
lower latitudes in the form of hydrates or ice in the top one meter of the regolith, have the
potential to change ISRU technology selection. A brief technology assessment was performed
for the most promising Mars atmospheric gas processing techniques: Reverse Water Gas
Shift (RWGS) and Methanation (aka Sabatier), as well as an overview of soil processing
technology to extract water from Martian soil.

NASA NTRS - 2011: Evaluation of Mars CO2 Capture and Gas Separation Technologies

NASA NTRS - 2017 (slides): The Technology and Future of In-Situ Resource Utilization (ISRU)

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#97 2020-01-05 10:47:53

SpaceNut
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Re: In-Situ Propellant Production, design a opensource demonstrator

repost:

louis wrote:

This is a good description of what is required:

https://www.thespacereview.com/article/3484/1

The Exytron approach at Augsburg might be relevant:

https://www.carboncommentary.com/blog/2 … -and-reuse

They do seem to have an installed pilot project:

https://exytron.online/en/news/

It would obviously need scaling up.

This Danish biogas planet has successfully experimented with a methanation plant...but again, looks like they need to scale that up.

https://www.lemvigbiogas.com/MeGa-stoREfinalreport.pdf

But this might be where Space X would go for manufacture or consultancy advice for their own manufacture.

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#98 2020-01-11 14:51:17

SpaceNut
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Re: In-Situ Propellant Production, design a opensource demonstrator

599 page document
http://strategic.mit.edu/docs/PhD_2016_do.pdf

Towards Earth Independence – Tradespace Exploration of Long-Duration Crewed Mars Surface System Architectures

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#99 2020-01-11 16:00:35

tahanson43206
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Posts: 3,109

Re: In-Situ Propellant Production, design a opensource demonstrator

For SpaceNut re #98

What a find! Thanks!

The author is from Australia.

NASA assisted with funding.

(th)

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#100 2020-06-10 19:44:57

SpaceNut
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Re: In-Situ Propellant Production, design a opensource demonstrator

Some reactors with control of temperature and catalyst will do better than 44 kilograms of carbon dioxide that is converted into 16 kilograms of methane in the Sabatier process, you need four kilograms of hydrogen. The Sabatier process only produces 36 kilograms of water in the balanced reaction.

An optimized system of this design massing 50 kilograms “has been projected to produce 1 kg/day of O2:CH4 propellant… with a methane purity of 98+% while consuming 700 Watts of electrical power and of course that's wen we say ouch for the size of the power source required for the production rate for a bfr starships use.

Overall unit conversion rate expected from the optimized system is one metric ton of propellant per 17 megawatt-hours energy input.3 So assuming all feedstock is available to feed the processing the power to produce a full load of methane (in gaseous form) for a BFR (240 tons) is estimated to be in the neighborhood of 4.1 gigawatt-hours.

Hercules reusable Mars lander
3085a.jpg

https://sacd.larc.nasa.gov/files/2018/1 … -Paper.pdf

https://ntrs.nasa.gov/archive/nasa/casi … 006324.pdf

https://ntrs.nasa.gov/archive/nasa/casi … 005557.pdf

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