Nuclear vs. Solar vs. Others

Calliban · 2022-08-12 07:49:20

kbd512 wrote:

Calliban,
We could use high-Silicon cast Iron pipes tp resist corrosion:
High Silicon Cast Iron

Good idea, I think. These cast irons will be the first metals we can produce on Mars in volume. High Si cast iron has poor weldability, but at the low pressures and temperatures we are talking about here, we can rely upon flanged sections. Brittle failure concerns can be negated by robust design factors. According to the links I have read, cast irons have low viscosity when liquid and low melting point, allowing them to be cast into complex shapes. We could therefore use inserts made from a soluble salt to cast heat exchangers directly into the vessel. Steam pipes, condenser body and pipes, turbine casing and fixed blades, can all be cast from the same material. The turbine and generator are the tricky bits. It would be really neat if we could design a plant that didn't need any pumps!

Tensile strength of cast iron varies from 150-500MPa, depending on type. That is comparable to plain low carbon steels, although the brittle fracture issue may require pipes to be thicker. But the simplicity of casting makes it the best option on early Mars. Most components could be cast in simple sand molds. Moving turbine blades will probably need to be imported from Earth, as I suspect, will the generator. The turbine shaft itself may be suitable for casting. Bearings may need to be imported as well, though the seats and housings can probably be made on Mars. Valves will mostly be piston type, and will be hydraulically actuated. These will require some machining to get tolerances right, but that can probably be done on Mars with cast components.

For low pressure nuclear systems, Mars made cast iron can comprise the bulk of these systems by mass. The use of castings for reactor vessel, heat exchangers and most secondary side systems, would allow nuclear generating capacity to be built up very quickly. This will be a neccesity for actual colonisation of Mars, as every aspect of life there appears to require vast quantities of energy. At one point it was estimated that a constant power of 100kW per person woukd be needed. That is just an insane amount of power. For it to be achievable, energy nedds to be dirt cheap.

Using heavy water as moderator and by removing fission products on a continuous basis, this reactor can operate using a mixture of low enriched uranium and thorium salts. AHRs operated in this way, have the best neutron economy of any known reactor. Over time, 233U breeding from 232Th, will allow uranium inputs to be tapered down. Eventually, a fuel cycle based entirely on Martian thorium can be established.

Fission product removal will take place in stages. Iodine is volatile and will accumulate in the reactor plenum space along with noble gas fission products, hydrogen (deuterium) and oxygen. Deuterium and oxygen can be continuously recombined by passing them through a sponge of hot nickel foam. The nickel foam provides a catalytic surface. Iodine will be captured in activated carbon filters. Noble gas fission products will be discharged into the atmosphere through a stack. Dissolved fission products can be removed by removing a portion of the fuel moderator mix each day and allowing decay heat to boil off the heavy water, which is then returned to the reactor. The mixture of solid actinides and fission products can then be separated by density and solubility. Fission products can be the stored in cast iron casks in dry storage facilities. AHRs will produce about 300kg of fission product wastes per GWth-year. So the volumes of waste produced by a Martian city will be small. Even assuming a power requirement of 100kW per capita, a 1 million inhabitant city on Mars would generate just 30 tonnes of high level waste per year.

Last edited by Calliban (2022-08-12 08:38:40)

Calliban · 2022-08-15 17:24:50

On the topic of Aqueous Homogenous Reactors. In the previous posts, Kbd512 and I discussed some options for developing a very simple nuclear reactor that can be built on Mars using cast iron and low carbon steels. These will be the first metals that we are able to produce in abundance. Being able to build reactors using grades of cast iron would allow a Martian colony to expand its power supply rapidly and thereby grow rapidly. One particular issue with using cast iron and carbon steels in water based reactors is corrosion.

It turns out that this may not be a problem after all. By adding 55ppm of technetium to water within the primary circuit and within the boilers, corrosion is entirely suppressed.

https://en.m.wikipedia.org/wiki/Technetium

Wikipedia wrote:

'When steel is immersed in water, adding a small concentration (55 ppm) of potassium pertechnetate(VII) to the water protects the steel from corrosion, even if the temperature is raised to 250 °C (523 K).[89] For this reason, pertechnetate has been used as an anodic corrosion inhibitor for steel, although technetium's radioactivity poses problems that limit this application to self-contained systems.[90] While (for example) CrO2−4 can also inhibit corrosion, it requires a concentration ten times as high. In one experiment, a specimen of carbon steel was kept in an aqueous solution of pertechnetate for 20 years and was still uncorroded.[89] The mechanism by which pertechnetate prevents corrosion is not well understood, but seems to involve the reversible formation of a thin surface layer (passivation). One theory holds that the pertechnetate reacts with the steel surface to form a layer of technetium dioxide which prevents further corrosion; the same effect explains how iron powder can be used to remove pertechnetate from water. The effect disappears rapidly if the concentration of pertechnetate falls below the minimum concentration or if too high a concentration of other ions is added.[91]
As noted, the radioactive nature of technetium (3 MBq/L at the concentrations required) makes this corrosion protection impractical in almost all situations. Nevertheless, corrosion protection by pertechnetate ions was proposed (but never adopted) for use in boiling water reactors.[91]'

Technetium-99 is a radioactive fission product, with a high yield of 6.1%. On the primary side, technetium will be produced as a fission product. By allowing it to accumulate within the water, corrosion is naturally suppressed. If technetium can be extracted and put into the secondary side boilers, then corrosion can be eliminated on both primary and secondary side of the boilers. This means that both the primary circuit and the boilers can be fabricated from cast irons or carbon steel. This enormously simplifies the construction of the reactors.

The other difficult part of the nuclear power system is the steam turbine.
https://www.nuclear-power.com/nuclear-p … -turbines/

The steam input temperature for our turbine will be 150°C and pressure is 4.8 bar. At this low pressure, HP and IP turbines are not needed. A single LP turbine without reheat will suffice. However, the low density of the steam in LP turbines requires long blades. At a rotation rate of 1800 rpm, centrifugal forces are extreme. Blades are vulnerable to creep. To limit the potential for creep, blades are made from chrome vanadium steels. We could in fact use cast iron blades and either operate at lower speeds, mount multiple smaller diameter LP turbines on a single shaft or have multiple small generating sets. All of these options either reduce efficiency (i.e lowering rotation speed) or increase capital cost, i.e. multiple smaller turbines. However, some combination of these options would alliw turbines to be made from cast iron until Martian metallurgy has reached the stage where high quality Chrome vanadium steel blades can be produced.
******************************************************************************************

The Girdler sulfide process for producing heavy water, requires temperatures of 130°C. The low temperature AHRs under discussion here, can provide the heat needed to run this chemical process. This allows Martian AHRs to produce enough D2O for their own moderators and eventually a surplus for export to Earth.
https://en.m.wikipedia.org/wiki/Girdler_sulfide_process

Last edited by Calliban (2022-08-16 07:06:06)

kbd512 · 2022-08-16 15:16:09

Ductile Iron yields around 40ksi to 45ksi and fails at 60ksi to 65ksi. One Ductile Iron alloy, 100-70-03, yields at 70ksi, fails at 100ksi, and has a fatigue limit of 40ksi. It can be hardened up to 50 on the Rockwell C-scale. That's plenty of strength for pipes and reactor pressure vessels. Iron will be heavier than high-strength steel. There are some limitations. It won't be possible to take them to higher service temperatures enabled by stainless or super alloys. Garden varieties of 300 series stainless are remarkably similar, with respect to yield and UTS, to 100-70-03, except that 100-70-03 Ductile Iron has a 25% YS increase over 300. I think the figures of merit are base metal availability, total input energy, corrosion resistance, and ease of forming the metal into the desired shapes. Cast Iron does pretty well on all of those metrics. That said, I don't think making steel will be an insurmountable problem. There's not shortage of Carbon or Iron on Mars, it simply requires more energy input and process control to make high quality steel.

Making single-crystal super alloy blades is another matter entirely. Devising a repeatable process wasn't easy using Earthly resources. I say we either stick with a greater number of smaller steam turbines or import super alloy blades from Earth. To be clear, I don't think the capital cost of operating multiple smaller turbines is much of a consideration for people living on Mars. The major capital cost is sending anything at all to Mars. Reliability, redundancy, ease of manufacture / simplicity override most other design considerations. Having multiple smaller turbines may be necessary for sake of redundancy. No matter how reliable, I think it would be a mistake to be utterly dependent upon a handful of very large turbines and electric generators. Any significant failure could be catastrophic for the colony. Smaller turbines and electric generators that are easier to manufacture and transport are the better option.

Toshiba 250MW / 50Hz Steam Turbine

Some of this stuff could probably be imported from Earth, even though it's pretty heavy. If broken down into major sub-assemblies, a cargo variant of Starship could land it. As indicated above, for a 250MW steam generator setup, the generator itself weighs 277t and the steam turbine weighs 268t. Total weight for the entire setup is 2,800t and includes 74 line items. If you assembled the components onsite, they would fit and ship. I'm pretty sure no attempt to minimize the weight of the generator was made, either. PM generators of the type used aboard ships can be drastically lighter than the cheaper stationary power plant variety.

Calliban · 2022-08-17 15:39:42

We are left with the question of how much to import from Earth and how much to make on Mars. I don't see any way we can avoid having to import the generator from Earth. There are a lot of unknowns (to me at least) around how practical it will be to produce complex components and high grade materials on Mars. But from a cost point of view, importing components would not raise totalncost inordinately, if Musk is able to deliver Starship launches at $2m each. A 250MWe power generating system, weighing ~2800 tonnes, is just short of 100W/kg. If Musk manages to get launch cost to LEO down to $20/kg, then $100/kg delivered to Mars surface would appear achievable. This would imply an import cost of $1000/kW, which would only marginally increase the cost of generated power. Unfortunately, 268 tonnes somewhat exceeds the lift capacity of Starship 1. For Starship 2, Musk appears to be aiming at increasing launch capacity by 8-10×. That would allow quite large components to be shipped to Mars in one piece.

One option for the generator - In purely mechanical applications, like compressing gases or crushing ores, we could use a steam turbine to drive a hydraulic pump and then power mechanical applications using hydraulic motors. This allows reduced electrical generating capacity. The hydraulic pumps and motors are simple devices that we can cast or 3D print. For propellant production, we could use an LP turbine to directly drive an axial compressor. We still need electric power of course, but the more applications we are able to provide using direct mechanical power, the less we have to spend on imported generator sets.

Last edited by Calliban (2022-08-17 15:42:58)

kbd512 · 2022-08-17 17:15:55

Calliban,

If we can source Iron and Aluminum from Mars, then we should be able to make electric generators using equipment imported from Earth. We need a foundry, a forge, and a machine shop. There are no ways around that. At the very least we need the machinery to produce sheet metal, plate, and pipes. There's almost no point to setting up shop on Mars if we can't import the machinery and use the available resources to make that stuff there. We must import the first power plant and fabrication machines, but after that the raw materials and labor need to be sourced from Mars.

Mars_B4_Moon · 2022-08-26 04:20:11

California to ban gas-powered car sales by 2035, but rooftop solar policy hampers climate goals

https://pv-magazine-usa.com/2022/08/25/ … by-2035-2/

Ban on gas-powered cars by 2035?
https://www.foxbusiness.com/politics/ca … s-electric
in favor of electric vehicles - Californians would still be able to drive and buy gas-powered cars after 2035 but no new models would be sold in the state

Last edited by Mars_B4_Moon (2022-08-26 04:21:07)

Calliban · 2022-08-26 05:20:44

Mars_B4_Moon wrote:

California to ban gas-powered car sales by 2035, but rooftop solar policy hampers climate goals
https://pv-magazine-usa.com/2022/08/25/ … by-2035-2/
Ban on gas-powered cars by 2035?
https://www.foxbusiness.com/politics/ca … s-electric
in favor of electric vehicles - Californians would still be able to drive and buy gas-powered cars after 2035 but no new models would be sold in the state

Don't you just love it when starry eye'd idiot politicians start making technical decisions? Who needs engineers when political idealists can just decide what everyone should be using based on what 'feels right' for them. We are seeing just how well that works out in Germany right now.

Last edited by Calliban (2022-08-26 05:24:02)

Mars_B4_Moon · 2022-09-01 01:38:36

Switzerland legislates all new buildings must install solar

https://renewablesnow.com/news/switzerl … ly-796366/

'Why even environmentalists are supporting nuclear power today'

https://www.npr.org/2022/08/30/11199048 … many-japan

US to see renewable energy boom in wake of historic climate bill

https://www.theguardian.com/environment … solar-wind

Mars_B4_Moon · 2022-09-02 06:16:09

California lawmakers extend the life of the state's last nuclear power plant

https://www.npr.org/2022/09/01/11197789 … ower-plant

Mars_B4_Moon · 2022-09-07 08:57:07

California Activates 4 Emergency Gas Generators, Grid Suffers Major Defeat

Emergency energy generators to keep the power on amid heat wave
https://abc30.com/california-power-roll … /12206130/

SpaceNut · 2022-09-07 20:32:34

The generators in Yuba City and Roseville are reserved for extreme energy needs, like this week's historic heat wave. "Within 10 minutes, we can be at full capacity with these units. And full capacity right now for what we have got is 120 megawatts of generated capable power," said Tony Myers of the Department of Water Resources. "That's equivalent to 120,000 homes that can be powered by just these four units."

Seems that they could use some more of these to be activated to lower the heat in the power conductors.

Mars_B4_Moon · 2022-09-12 08:26:58

Tokyo plans to require that new homes have solar panels from 2025
https://www.japantimes.co.jp/news/2022/ … new-homes/

Mars_B4_Moon · 2022-09-24 03:21:29

Britain to cut red tape for offshore wind, oil and gas

https://www.bloomberg.com/news/articles … shore-wind

Mars_B4_Moon · 2022-09-24 09:58:40

Here’s how Canadian hydropower will power 1 million New York City homes from 2026
https://electrek.co/2022/09/21/heres-ho … from-2026/

China plans more moon missions after discovering a new mineral
https://www.siliconrepublic.com/innovat … r-missions

Calliban · 2022-09-27 22:36:00

Elon Musk: "Shutting down nuclear power plants is total madness"
https://www.businessinsider.com/elon-mu … &r=US&IR=T

SpaceNut · 2022-09-28 19:07:01

It would seem that some when its close chose to keep them running but when will they learn that the consumer is the one which if it were available would want units that were small spread-out more so as to not allow for grid overloads.

Mars_B4_Moon · 2022-10-03 22:22:03

"This Is What a Nuclear-Powered Future Might Look Like" "South Korea may have the answer"
https://www.bloomberg.com/opinion/artic … -look-like
"A draft long-term energy plan released recently calls for 201.7 terawatt-hours of electricity from nuclear by the end of the decade, or about 33% of the country’s total, aided by six new reactors. Coal, natural gas and renewables will each make up just over 20% of generation."

Nuclear fusion plant to be built at West Burton A power station
https://www.bbc.com/news/uk-england-not … e-63119465
Fusion is a potential source of almost limitless clean energy but is currently only carried out in experiments.
The government had shortlisted five sites but has picked the West Burton A plant in Nottinghamshire.
The plant should be operational by the early 2040s, a UK Atomic Energy Authority (UKAEA) spokesman has said.

Energy crisis: Spaniards seek wood pellets and solar panels to heat homes
https://www.euronews.com/my-europe/2022 … heat-homes

Last edited by Mars_B4_Moon (2022-10-03 22:22:15)

Mars_B4_Moon · 2022-10-12 07:41:29

I remember seeing SpaceNut maybe post news and Calliban discussing Air Compression the other day, I might search again for the thread later.

'China turns on the world's largest compressed air energy storage plant'

https://newatlas.com/energy/china-100mw-compressed-air/

The Chinese Academy of Sciences says the Zhangjiakou plant is capable of supplying the local grid with more than 132 GWh of electricity annually, taking on the peak consumption of some 40-60,000 homes. It'll save around 42,000 tons of coal from being burned in power stations, and reduce annual carbon dioxide emissions by around 109,000 tons – the equivalent of taking about 23,700 average American cars off the road.

The Academy says this design's low capital costs, long lifetime, safety and efficiency, along with its green credentials, position it well as "one of the most promising technologies for large-scale energy storage."

Mars_B4_Moon · 2022-10-17 15:24:30

Solar meets all electricity needs of South Australia from 10 am until 4 PM on Sunday, 90% of it coming from rooftop solar

https://reneweconomy.com.au/solar-elimi … uring-day/

Calliban · 2022-10-20 11:51:17

The green energy revolution is almost impossible.
https://www.manhattan-institute.org/gre … impossible

The productivity of wind and solar investments is extremely poor.

kbd512 · 2022-10-21 05:35:15

Calliban,

Your article appears to be high-level but sufficiently detailed research (in engineering details actually matter) and a source of independent / external confirmation that I knew what I was talking about when I asserted that the only intelligent use of grid-scale wind and solar power, from an environmental preservation perspective, was as a means of synthesizing hydrocarbon fuels from scratch. Doing that completely bypasses the need to store energy as heat or in batteries, both of which have absurdly poor energy density per unit mass of material. The only possible exceptions are hydro and rocks / salts / metals, because the cost is so low and so little input energy is required to use those materials (essentially limited to the cost of transporting the materials to the power storage device attached to the power plant), given that said mass of materials must otherwise be transformed, using input energy, from whatever energy source is used for that purpose.

It's abundantly clear to me that most people can't separate beliefs based upon false advertising from engineering reality. In my objective reality world, I cannot identify another like-kind energy source to replace hydrocarbon fuels. Moreover, no other research scientists or engineers can, either. I'm perfectly willing to accept that some of those people could be ten times smarter than I will ever be. If they can't figure it with trillions of dollars of funding, then what are the odds that I can figure it out with none of their education and resources? They've tried their hardest, but math and physics are unyielding to ideology. In objective reality, two plus two always equals four. If you start with an energy source orders of magnitude less energy dense, then that form of inefficiency ALONE, makes some concepts completely impossible.

For example, so long as Earth's air density is 1.225kg/m^3 and gravity is 9.81m^2, it's physically impossible to create an airliner powered by air, using all known materials science.

Will we put a nuclear reactor on a truck, train, or aircraft?

In almost all cases, the answer to that question is a hard "no".

Can you power a car with batteries in a practical way?

Over shorter distances of no more than 100 miles, yes. It's just barely feasible to do without making insane concessions on weight, input energy, reliability, and monetary cost.

Trains? No. Ships? No. Aircraft? It's technically feasible for very short flights aboard light aircraft, but otherwise utterly impractical, in much the same way that solar powered aircraft are absurdly impractical with the strongest and lightest construction materials available. You can invoke CNT fabric as your composite material, but then you have a 2 seat aircraft the size of an Airbus A380, which costs tens of millions of dollars to construct.

Can you power an airliner with batteries simply by "building it bigger"?

Again, that's not happening using current battery technology. The electric motors are more than capable of providing sufficient thrust, but something sufficiently energy-dense has to supply the input electricity, and the only form of energy capable of doing that is Hydrogen-based, and Hydrocarbon-based if we're "keeping it real".

This says it all:

Then there are the hydrocarbons and electricity needed to undertake all the mining activities and to fabricate the batteries themselves. In rough terms, it requires the energy equivalent of about 100 barrels of oil to fabricate a quantity of batteries that can store a single barrel of oil-equivalent energy.

100 barrel of oil energy input equivalent to store 1 barrel of oil energy as output, in the form of electricity, by using batteries as we know them. If battery energy density improved by 1 order of magnitude, meaning 10 times better than what we have today, it's still a losing proposition. Maybe we should just call liquid hydrocarbon fuels, "super batteries" that emit clean, renewable CO2.

tahanson43206 · 2022-10-21 06:09:50

For kbd512 re #271

Nice!

Maybe we should just call liquid hydrocarbon fuels, "super batteries" that emit clean, renewable CO2.

(th)

kbd512 · 2022-10-21 12:21:50

tahanson43206,

Re: "clean renewable CO2"...

Explaining basic physics to ideologically mentally disabled people gets tiresome. Sometimes it's easier to use marketing BS to sell an idea to them when they're otherwise not intelligent enough to understand how it works. Every Lithium-ion battery that stores 1 Barrel-of-Oil (BoE) energy equivalent requires an astounding 100 BoE input. Lithium-ion batteries are fantastic marketing BS, but they simply don't do what our weather changers think they will do. Physics dictates that batteries cannot do what those people want done. The unvarnished truth is that there are only dirty vs dirtier energy sources, and if we decide to make human civilization battery-powered, then we will only succeed in making Earth's environment dirtier and more toxic than it already is.

Imagine if I was in the business of making aircraft from Depleted Uranium, and called them "thrust-enabled flying machines with fantastic diving rates", in order to make it easier for them to return to Mother Earth when the flight needs to end. What's all this "gliding nonsense" about? Tired of waiting in the pattern for your turn to land? Why can't we get our planes back on the ground, pronto? Well, what if you could get your favorite airliner back on terra firma in mere seconds, simply by cutting the power? With our new Depleted Uranium aircraft, constructed from only the finest in Heavy Metal technology, that will no longer be a problem during your next flight. The instant the thrust stops, the flying stops with it. Problem solved. See you in, I mean "on", the ground after your next flight.

See what I did there? I used marketing BS to sell an inexcusably bad idea to people who don't know any better.

If making aircraft from Depleted Uranium seems rather foolish and not a worthwhile pursuit to everyone else, then I would tend to agree, and hope that people who can do basic math know how much more foolish it is to power cars / trucks / trains / ships / airplanes using batteries alone. Depleted Uranium alloys are vastly better aircraft construction materials than Lithium-ion batteries are a suitable power source for that same aircraft. Uranium-Titanium alloys (0.75% Titanium, the remainder being U238; with a rather lengthy and precise heat treatment and annealing process) have a yield strength approximately double that of 7075-T6 Aluminum alloy, but still very susceptible to stress-corrosion cracking afterwards without superb oxidation protection and limiting the stress applied to something well under 130ksi, meaning no better than 7075-T6 in practice. We mostly quit using Aluminum in airliners, unlike small aircraft, because it's too heavy relative to the performance requirements placed upon them. Aluminum obviously works for aircraft construction, but GFRP / CFRP works a lot better when strength-to-weight ratio is a consideration, weight being the mortal enemy of all flying machines.

If you never see people like me proposing something as nutty as using U238 alloys to construct airliners, then why do we have so many people advocating for something orders of magnitude nuttier, such as powering cars, trucks, ships, trains, and aircraft with batteries?

If I had to input 100 barrels of oil (4,200 gallons of hydrocarbon energy storage) to get 1 barrel of oil (100 barrels of oil transformed into a battery that stores the energy equivalent of 1 barrel / 42 gallons of oil) out, I would call that an abhorrently bad energy trade. Anybody proposing that we do that on a human civilization scale should have their head checked to see if they have more than a few screws loose.

Does anyone else here see the obvious but surreptitiously laid "energy trap" here, or am I the only one?

We transform all this stuff into photovoltaics / wind turbines / batteries using 100 barrels of oil energy and get, at most, 1 barrel of oil energy as output. In reality, it's far worse than that, because the 1 unit of energy storage output is only the energy storage. The photovoltaics and wind turbines are similarly bad energy trades.

Why do I want to use solar thermal, then, to make new hydrocarbon fuels?

You convert 25% of your 1kW of photonic power from the Sun, into electrical power, using affordable photovoltaics. Those last for 25 years at most before the electronics begin to fail. In my case, most of those electronics didn't last 1 lousy year. I can blame lots of things for that, but excuses don't matter in the real world, only results.

You convert 75% to 85% of your 1kW of photonic power from the Sun, into thermal power (without invoking any new / magical / rare / expensive technology, only polished Aluminum), using solar troughs that last 75 years, same as any other thermal power plant, in actual practice. IF you want to convert that into electrical power using sCO2 gas turbines, you still get 37.5% of that, which is better than actual onshore wind turbines and as good as photovoltaics that cost $1M per 1kWe that won't last for 75 years using any known technology. 75 years from now, or whenever you feel like it, you re-polish the shiny metal surface, good as new, and melt down any corroded pipes carrying heat transfer fluid. You employ a bunch of people to make real usable storable energy (Methane, Propane, gasoline, diesel, kerosene), that stimulates the economy, and you can continue recycling CO2 until the Sun incinerates the Earth a couple billion years from now. Presumably, we will have magical battery / photovoltaic / fusion / anti-matter technology by then, but not now, because we still don't know how to do that and it'll be decades before we can implement unworkable forms of those technologies at a human civilization scale.

When the energy that moves people and machines is divorced from a finite consumption cycle that relies upon "easy access" (cheap drilling) and "easy money" (banks handing out money like it's candy), then we can move on to bigger and better things. Money is a proxy for energy and work in the physical world, which is why "the broken window fallacy" is always fallacious. Breaking all the windows in a city is artificial economic stimulation that takes money / energy / labor (all at the same time) away from food / shelter / water / clothing / technological "goodies" (that only come from making windows only when required, then spending money / energy / labor on other things). Until energy is limitless and we invent Star Trek Replicators, that rule is ironclad, every bit as real and inescapable as gravity or thermodynamics. Nobody "made it up" to confuse communists and other energy / economics illiterates. I wish a lot of things didn't work the way that they do, but wishing physics would "go away" will not make it so.

They do still teach math and engineering in college, but you have to show up to class, take notes, and ask questions if you don't understand. After class is over with, then you have to apply what you've learned, meaning prove to everyone else that your degree is worth the paper it's printed on.

Is it any wonder that some of us question the logic behind what we're ultimately doing by building these "bridges to nowhere", especially when we know how little uncommon sense is applied?

I'm clearly not the only one.

kbd512 · 2022-10-21 15:43:13

Some here may not that I advocated for making the solar troughs from lower-cost steel, and that's true. The polished Aluminum is only a surface coating. This is how automotive manufacturers make engine exhaust systems. They take a cheap low carbon steel, apply a thin coat of Aluminum to protect the steel from corrosion, and then that system survives hot CO2 and water for years before a replacement is required.

Pure Aluminum alloy sheet metal would also work, but it would be a bad energy trade and at least three times more expensive than necessary. My solution is about getting things done at minimal cost and environmental damage (Aluminum is worse than steel, but something with the strength of steel is required, which is why it's used), not spending money to please engineers or purists.

I need a lot of steel and concrete, some Aluminum for the mirror coating / surface finish, but comparatively trivial quantities of everything else. The working fluid is oil because it flows well, sealing in a hot liquid is a lot easier than a hot gas in this case, and that also minimizes cost. If this was done with nuclear thermal vs solar thermal, then I'd need a lot less concrete and steel, but then I'd have a lot of radioactive / heavily irradiated steel after 75 years that I can't easily transform into a new nuclear reactor.

Since this solution is about making fuel vs making electricity 24/7, I use my ease-of-recycling advantage to easily scrap the steel and Aluminum when I'm done using the solar troughs. I'll melt the Aluminum coating off the steel, then melt the steel, then make new solar troughs in another 75 years or so (assuming some sort of structural damage was done to the steel). If there's no damage, then we re-polish or reapply and polish the Aluminum coating, sort of like spray painting a car after the paint fades or gets chipped after many years of use. Since the solution is mostly easily recycled steel and Aluminum, I don't need any special technology to deal with radioactive components.

This solution produces fuel in daily batches, so that daily shipments of finished product can be pipelined around the country or shipped to foreign customers such as our allies in Europe. I prefer Propane because it's storable at modest pressures at room temperature (250psi at 120F, IIRC), burns cleaner than gasoline or diesel or kerosene, and can be used in any kind of internal combustion engine. Propane doesn't "go bad" within 6 months the way gasoline or diesel or kerosene do, meaning it's indefinitely storable. If we need or want to, we can continually build up a surplus of energy storage (to remove more CO2 than we add back into the Earth's atmosphere). We can also make those other products, but only at the cost of even more input energy. We may decide that even Propane is not energy-dense enough, and convert the output product into crude oil. However, I tend to think Methane (for heating and electricity) and Propane (fuel for vehicles) will be the primary outputs. We'll still need diesel fuel because Propane alone doesn't burn well in diesel engines, but up to 1/4 of the fuel input can be Propane.

Modern spark-ignited engines can be highly efficient, as Mazda and Toyota have proven- almost as efficient as diesel engines in some cases. If you put as much boost into a gasoline engine as a diesel engine, then the spark-ignited engine will generally produce more power and torque than a diesel engine, at a considerably lower engine weight. The 12L to 18L displacement heavy duty trucks run 25 to 50 pounds of boost in most cases. The big diesels that power them make 450hp to 600hp, but weigh north of 2,500lbs. If you put 25 pounds of boost into a 500 pound LS-based engine, then it will easily produce well over 1,000hp.

With 24psi of boost using a twin-turbo setup on a 5.3L LS engine (3.622" stroke length), you're already at 400hp at 4,000rpm. If you tripled the displacement, then you'd be making 600hp at 2,000rpm, but why bother if you can use boost and gearing and higher-Octane Propane fuel to make more power. At 29psi, you're already at 600hp before 4,000rpm. Doubling displacement would roughly double the power output, so you're at 600hp at 2,000rpm, which is virtually identical power at identical rpm to an even-larger / heavier 12L to 18L diesel engine.

By running 25psi of boost, 632CID / 10.4L Chevy big block V8 would be little different in performance when compared to a much larger and heavier diesel engine, and compression ratio could increase by burning Propane fuel, so thermal efficiency increases with it. With a much smaller displacement 454CID (same basic Chevy Big Block design), you're already at 600hp by 3,800rpm and a little less than 850 ft-lbs of torque, using 16.5 pounds of boost. Your all-cast Iron engine weighs about 800lbs with all components included. A BBC / BBF / BBM would easily fit between the frame rails of a semi, which lowers the CG of the vehicle drastically, and takes about 1 ton of weight off the overstressed front axle of most big rigs. The 200hp to 300hp or so, which is required to keep a fully loaded rig moving at 70mph over a flat and level road, would equate to an engine rpm no greater than that of a modern 12L to 18L inline-6 diesel engine, which runs 1,500rpm to 1,800rpm at 70mph.

To be clear, this V8 engine would not last as long as the much larger diesels, but it's also a much cheaper engine to rebuild or replace, as compared to a Caterpillar ACERT or Cummins ISX15 or similar Detroit Diesel DD16 engine. It's not a million mile engine, but 100,000 to 150,000 miles is doable. Removing the engine from the frame rails to rebuild it is also a realistic low-cost option that doesn't require removing the cab and a forklift. These big blocks are run at 300hp to 400hp level for extended periods of time in smaller trucks or boats or as backup generators, but running at 600hp would require a stronger block design, similar to those from Dart, which I would expect could truly "run" at 600hp and live. Even with these limitations, the cost of several overhauls would be similar to the cost of the overhaul components or labor alone to rebuild an ACERT or ISX15 engine.

What you sacrifice in ultimate engine durability and reliability, you more than make up for in terms of energy consumption to move several extra tons of engine / chassis / fuel around using much heavier diesel engines. Your semi-tractor can get away with running 4 Super Single tires in most cases, as opposed to 2 "normal" steering wheels and 4 Super Singles or 10 "normal" tires. These two factors alone have more impact on fuel economy than using batteries predominantly made with and recharged by hydrocarbon energy. BBC (Big Block Chevy) is a good trade-off in this case, because the parts are plentiful and still made in mass quantities, they're easy to work on, and inexpensive to completely replace if you do grenade an engine every so often.

You do need beefier components to make this work. To wit, an engine block made from CGI or ductile cast Iron vs grey cast Iron, gears vs timing chains or belts, thicker pushrods and upgraded springs, stainless intake valves and Inconel exhaust valves, forged Aluminum 2618 alloy vs cast pistons, beefier forged steel connecting rods, piston oil squirters to remove heat by coating the underside of the piston with oil, a fully counter-weighted crankshaft, splayed-bolt billet steel main caps to secure the crankshaft to the block, a hydraulic roller camshaft, Aluminum heads to dissipate the heat faster, a large capacity Marine style oil pan, an oil cooler to cool the turbos oil supply, and an increased radiator capacity to remove the heat associated with running the engine at high constant power output levels. Believe it or not, almost all of this stuff is standard fare in the aftermarket, meaning all of these components are considered to be basic upgrades required for performance applications, where engine power output levels can soar to 2,500hp and frequently approaches 1,000hp in more modest applications.

In this case, General Motors outright sells a big block engine package that was specifically designed for this type of duty use, namely the 496CID BBC, which greatly resembles an oversized LS-platform engine, rather than a traditional BBC of 1960s to 1970s vintage. They used it to power their Kodiak Topkick medium duty line of trucks between 2001 and 2009. One manufacturer of alternative engines for medium duty trucks and school buses sells their own naturally-aspirated version of this same engine that's fueled by Propane or CNG, and primarily intended for use in school buses as a cleaner alternative to diesel and gasoline engines. Raylar Marine has further developed aftermarket intakes and Aluminum heads for offshore powerboat racing. Turbocharging makes it feasible to use an improved version of GM's L18 496CID / 8.1L BBC for heavy duty trucks. A handful of BBCs, with reduction gearing, have also been used to power scale replicas of the P-51 Mustang.

GMC C7500 TopKick with Propane Tank:
img.axd?id=7289884246&wid=4326209787&rwl=False&p=&ext=&w=392&h=294&t=&lp=TRK&c=True&wt=False&sz=Max&rt=0&checksum=t5sEOlW%2BjupJccC9LBiME3g%2BigR9Di01O72xClALNRY%3D

EDIT: Stock GM L18 496cid / 8.1L BBC:
GM-8.1L-medium-duty-lrw.jpg

EDIT #2: Raylar Engineering Link (490hp at 3,000rpm with only 9lbs of boost!):
MerCruiser 496 Magnum / 496 Magnum High Output Marine Engine Aftermarket Parts

If you turned that sucker up to 25 pounds of boost, then it would out-pull a Caterpillar or Cummins at the same rpm! Granted, the engine wouldn't live very long if you did that, but it's remarkable how much more powerful gasoline / spark-ignited engines can be, for a given weight target, when compared to diesels. We think of diesels being very powerful because they produce their power at lower rpm levels, but the corollary to the statement is that you really don't want to spin them any faster, and they only produce as much power as they do using crazy-high boost levels. Do they work? Obviously, but how much of a deadweight penalty are you willing to live with for a fuel economy improvement that's readily achievable using spark-ignition, far less boost, and a throttle opening that's closer to WOT on account of how the engine is operated?

So... Can we meaningfully reduce energy consumption and associated emissions?

Yes, but it won't be done using any known battery technology. We have the tech to drastically reduce fuel demand for passenger vehicles and trucks. We're not applying it, for various reasons. Instead, we've decided to play with whiz-bang toys that everyone who isn't mathematically illiterate flat-out knows is not going to replace oil.

Make some choices here.

Option A - Fight basic physics / thermodynamics / math when it comes to photovoltaics / wind turbines / batteries and lose
Option B - Focus efforts on fuel consumption reduction (more reasonable vehicle weights and engine power output levels), fuel synthesis (using solar thermal power), cleaner but still practical alternative fuels (Methane and Propane), and; use nuclear fission instead of gas turbines or coal to generate electricity since that demand exists 24/7/365
Option C - Do nothing and eventually run out of energy

There are no other realistic options into the foreseeable future. It's highly improbable, if not physically impossible, that any will be forthcoming. Keep holding out hope that a miracle will happen, despite none having happened with the trillions of dollars invested into photovoltaics / wind turbines / batteries to date, or read the writing spray-painted in big red lettering all over that wall.

Last edited by kbd512 (2022-10-21 16:11:13)

Calliban · 2022-10-21 16:15:59

I have to admit to being sceptical that solar thermal power will produce affordable liquid fuels. The power density of sunlight is low. Photovoltaics will convert some 15-25% of incident sunlight into electrical energy. What is being proposed is solar thermal power driving thermochemical water splitting. With thermochemical water splitting, some 30% of sunlight may be captured as chemical energy in ammonia. Somewhat less in synthetic hydrocarbons due to the need to reduce CO2 to CO. With trough collectors, we are replacing silicon with aluminised steel. Steel is at least recyclable. But we are still talking about huge quantities of steel to produce powerplants sufficient to manufacture a large fraction of the world's hydrocarbons. We can guage practicality by calculating how much steel is required per captured MJ. Knowing the embodied energy of the steel we can then estimate an energy payback time. If that time is short compared to realistic plant lifetime, the concept may hold promise.

Last edited by Calliban (2022-10-21 16:25:17)

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