Current Gasoline/Petrol Price$

SpaceNut · 2023-04-18 23:13:51

City density is why we are not using trains and subways more but in a nation that is not designed for walkability we are left to gap fillers to bridge the distances. Take for instance the daily commute where there is a coastal bus route which is plausible for me to take but to get to the location for pick up means 7 miles of travel by foot or by vehicle. The cost to ride sure is about the cost of the gas to go all the way with one's own vehicle. Then if you need to leave early or take it late to work, then it does not work at all. Not a savings and does not change the use of fuels let alone lower the carbon footprint that we are continuing to create.

Does the electrical change the equation when its low ridership for the subways or trains versus single vehicles?

For the longest time we as consumers wanted speed/horsepower and as we learned how to build lighter cars that equation has not changed other than to make some more efficient for fuel milage and smaller.

While we know nuclear is part of the energy answer but its cost, life cycle that stinks as well as size along with its waste that is a problem.

kbd512 · 2023-04-19 13:24:52

SpaceNut,

Since we're not going to change every city in America, let alone every aspect of how we use energy, and a continent-sized country was never intended to be "walkable" to suit the personal aesthetic preferences of anyone, cars were developed as the most practical alternative. We developed modern cars because America is huge and having everyone going to one place is either very inefficient or very time-consuming. I have lived the "walkable city life". I've spent days / weeks walking and waiting. I don't mind walking and enjoy the time it gives me to think, but my time also has value. Walking at least 2 hours per day means that time is not spent cooking / cleaning / washing clothes / spending time with my children. I still walk with my son to school sometimes, but that turns a 10 minute round-trip task into a 30+ minute task. It would add 1 hour to going to the store. Could a little plastic car with a small battery change that? Sure, but then we're right back to using more energy. There's no "winning" here. There's physics and energy.

Battery technology could change the paradigm if and only if it was at least 10X more energy dense than it presently is (2,500Wh/kg vs 250Wh/kg). There are no orders of magnitude improvements possible using existing electrical technology. Li-ion has had a 3.5X gravimetric energy density improvement from its earliest commercial forms of the technology to the present, less if we consider the overall battery pack, and the cost goes up with every successive generational improvement. The electric motors / generators and batteries are already 95% efficient, so they're already tapped out as far as major efficiency improvements are concerned. If both were 100% efficient, that buys very little. There are no fantastic gravimetric energy density increases to be had. Lithium is already the lightest metal capable of high ionization / electron movement potentials. There are no lighter materials to work with if weight is a consideration, and it's important for any moving machine. That only leaves improvements to battery internal structure (3D vs 2D) and stabilizing chemicals (Cobalt) to suppress dendrite growth and production cost (lower cost anodes or active materials) / lower energy or more abundant materials, which all trade off gravimetric or volumetric cell capacity or cell life in favor of some other desirable characteristic. There is no "do-all" battery technology.

My hope is the lower cost batteries made with Sodium / Sulfur / Silicon can replace Lithium while providing roughly equal overall performance, since Lithium remains scarce and expensive by way of comparison. Whether or not that's possible remains to be seen. There is no quantum leap improvement within the electro-chemical battery space. The only reason we could afford to mass produce electronic vehicles at all was the massive increase in energy / material wealth that hydrocarbon fuels provided.

No energy efficiency improvement has ever led to a reduction in energy usage. You said that yourself, so you're as well aware of that fact as I am. Whether it would theoretically improve emissions is therefore highly debatable. I've seen no such evidence thus far, throughout human history. The moment we make a process or machine more energy efficient, it gets used to such a greater degree that no energy reduction actually happens. If you make cars 50% more energy efficient, then people will simply drive more than they already do. Any argument to the contrary is comically ignorant of basic human behavior.

Nuclear waste has only ever been a problem in the minds of people who don't want nuclear power. No other technology produces less toxic waste, and it's not even a contest between nuclear power and any other power technology. The toxic wastes produced by all other forms of energy, especially photovoltaics / wind turbines / batteries, have rocketed past the quantities of toxic wastes generated from nuclear power, and that's before fuel reprocessing. The quantity of waste from nuclear power has yet to pick up enough speed to get airborne while the wastes generated by photovoltaics and computing electronics and batteries have already made the jump to hyperspace. This state of affairs is only possible because the minds of our "green energy" characters are denser than neutron stars. They keep slamming their heads into brick walls expecting the brick walls to give way. Apart from brain damage, no other result is more likely to happen.

The cost of nuclear power is entirely dictated by the NRC, which is run from the top by Democrats, even under President Trump, and their singular goal is to prevent the greater adoption of nuclear power, because that would somehow invalidate their aesthetic preferences for more wind turbines and solar panels (things that wear out quickly and need to be frequently replaced, at great cost, thereby making money for their party donors- more planned obsolescence in action and why solar thermal hasn't seen greater adoption). Nature doesn't care about anyone's aesthetics-driven beliefs about energy. Some energy sources really are wildly more powerful than others, and that's unlikely to change in the near future. There are no viable substitutes for nuclear power or hydrocarbon fuels because nothing else remotely approaches their energy density. We can afford some inefficiency when using those energy sources and still use them to power practical machines, regardless of aesthetics, on account of how much more energy we can get out of them, per unit time, to begin with. Even I think some of the solutions are ugly, but working still trumps ugly in my book because cosmetics are for artists and I'm not one of those. Going without energy is far uglier if you think a tailpipe on a car is objectionable.

Nuclear fuels and hydrocarbon fuels are king and queen of the energy density game. The king can only move one square at a time, but when he does he's an unstoppable force. The energies used to fuel stars and heat planetary cores are unimaginably powerful. Everything else looks like a tinker toy by way of comparison, even with the very latest technology. Hydrocarbon fuels can drive machines really fast in one direction for brief periods of time, basically traversing any number of squares on the board, hence the comparison to the queen. The wind and solar machines are basically pawns. You need lots of them or they don't amount to much. If you have too many, then they quickly consume all of the board space and hinder the playing of the game.

SpaceNut · 2023-04-19 21:23:48

Walking, riding or driving for 2 hours out of every day does mean you are investing to make money.

Tonight's gasoline cost at the pump rose to $3.59 and will need fuel to tomorrow to finish out the week.

kbd512 · 2023-04-20 05:37:10

SpaceNut,

My entire point is that time requires energy for all living things. The amount of time which must be devoted to any task is greatly reduced when more energy is available to complete the task, even when inefficiencies are present. That means other useful tasks can be completed in a given period of time, such as one day. Thanks to hydrocarbon fuels, you can work 50 miles away from where you live, put in 8 hours of work per day, still get all 3 of your meals, go home to get a good night's sleep, and do it all over again the next day. How much fuel you use to get to and from work, or to heat your home, is a matter of choice. We could all drive much more efficient cars that are much simpler and lighter, or we can all drive much heavier and more energy-hungry vehicles, or we can create hybrids. However, complexity and the energy density of the fuel source drives up weight and therefore cost.

EVs haven't created lower cost vehicles because of the weight and expense of the batteries. That doesn't make more efficient EVs impossible, but they cannot use electro-chemical batteries unless the batteries are made from very common materials, are very cheap to make, and very cheap to recycle. Nothing of the sort has been invented thus far, which is why I suggested taking different approaches, such as storing thermal energy from electrical heating in a tank of hot liquid (water or paraffin wax) and using a refrigeration loop to transfer thermal power to a motor of some kind (pneumatic, hydraulic, or electrical). The efficiencies possible with batteries no longer exist, but that efficiency was almost entirely illusory to begin with (you had to use the vehicle for a period of time beyond its warranty period before there was a net energy benefit), given the amount of input energy required to create the batteries to begin with.

My suggestion still has no direct emissions, is still much lower cost than either an internal combustion or electronic battery powered vehicle, and is very easy to recycle when that time inevitably rolls around (accepting that no machine lasts forever, accidents happen, etc).

Calliban · 2023-04-21 06:47:41

Adam Rozencwajg on the energetic problem with the energy transition.
https://m.youtube.com/watch?v=xNaZw6fjk … FqZw%3D%3D

He makes some very interesting points. Most of the investment in low EROI energy technologies (especially wind, solar and EVs) took place in that narrow window of time between the GFC in 2008 and the end of the COVID pandemic (2022). This was a period of historically low energy costs and close to zero borrowing costs. These two factors (he doesn't mention Chinese mass production and dumping) made renewables appear more sustainable than will be the case in the long run. Low energy costs reduced capital costs of very materials intensive projects. Low interest rates made capital investments easy to afford. But the low energy costs permitted by the shale revolution did not last forever. The shale revolution suppressed oil and gas prices for a decade, but the days of growing production are behind us and 2 of the 3 large US shale oil basins are post-peak, with the third (Permian) expected to peak before 2025.

Rozencwajg is extremely bullish on nuclear power, especially Gen 4 technologies. He makes the point that the high costs of recent nuclear projects are due to having to restart nuclear build as a new industry, coupled with an NRC which is actively hostile to nuclear power. His opinion is that we are running into an energy crisis and that the public is likely to turn against green groups and anti-nuclear politicians as their living standards come under increasing pressure. I think we can see that happening already.

Last edited by Calliban (2023-04-21 06:50:18)

Calliban · 2023-04-21 06:56:46

Kbd512, a stored heat battery would have low capital cost compared to any electrochemical system. Most of the materials involved are very cheap, both financially and energetically. I can see this working in a lot of ways for stationary applications. In mobile applications, energy density may be a limiting factor. The latent heat of melting of ice is ~0.1kWh/kg. Let us assume we have a hot and cold store, each with a latent heat of 0.1kWh/kg, with a heat engine operating between them. Let us assume that the heat engine has about the same efficiency as an ICE in a car, say ~20%. The effective mass energy density of our heat battery is 0.02kWh/kg. That is about 1/8th the energy density of a lead acid battery and about the same as supercapacitors.

A Tesla 3 with a standard 50kWh battery, has range 350km, equating to an energy consumption of 0.14kWh/km. If we powered the same vehicle with a heat battery, the battery would weigh some 7kg per km of range. To get 50km of range (30 miles), the battery would weigh 350kg. If you are content with a short range vehicle to move around town, this may be satisfactory, especially if there is charging infrastructure at both ends. But this vehicle is clearly very limited in what you can hope to use it for.

For large ships and trains, things are a little easier. For stationary applications, the heat battery is probably our best option for large scale energy storage. There are also plenty of direct heat applications that don't require any backward conversion of heat into mechanical power. For a car it is more difficult, but it could be made to work so long as you are content with short range. Such a battery would have low upfront cost and long operating life, as there really isn't anything to degrade. So a vehicle with a heat battery could be very long lived.

Another cool thing about this is that the battery can be charged using mechanical power, which drives a heat pump, which could be a positive displacement pump that work at a range of speeds. Electricity is not a necessary input. This has sustainability benefits in small scale systems, which we have talked about before. A purely mechanical wind turbine is something that is simple enough for a lot of people to build themselves if they have to. Mechanical systems using hydraulics or direct shaft power would not require exotic materials. Just brick, stone, cement or mortar, wood and carbon steels. This is something I am confident that a lot of people could build for themselves with some effort. The Amish have already gone down this route, using wind turbines to produce LP compressed air. A car that is charged with mechanical power would probably interest them.

Last edited by Calliban (2023-04-21 07:35:46)

tahanson43206 · 2023-04-21 07:00:45

For Calliban re #855

You had mentioned possibly investing in a copy of Dr. Zubrin's latest book. When you do make that investment, I think you will be pleased at the arguments he presents in favor of massive construction of nuclear plants.

I have created topics for the book. One is for positive responses, and the other is for the inevitable nitpicks and even outright pained responses from those whose oxen are gored by Zubrin's occasional jabs.

My interest is in seeing how we humans can move beyond preaching to the choir.

I noted with interest that there is a news report of a major expansion of Gen 4 reactors in Poland, which has (apparently) made a 4 Billion USD committment.

I sure would like to know what 4 Billion USD buys in this market! There are US entities that could pull 4 billion USD out of the petty cash drawer.

(th)

Calliban · 2023-04-21 07:31:03

TH, I was waiting for the paperback to come available. But it is in my amazon basket.

tahanson43206 · 2023-04-21 09:59:10

For Calliban re #858

Thanks for the feedback .... there ** is ** NO hard copy.... the modern choices are paperback and eBook.

I chose the paperback because I like to interact with a book, and it is less satisfying to "mark up" an eBook, even though modern software makes that possible. eBooks have their place, and on a trip is a good example, but for day-to-day slugfest reading, a printed surface to mark is my favorite.

(th)

kbd512 · 2023-04-21 15:37:28

Calliban,

A car that can drive 30 miles is still much faster than walking. In most cities 30 miles of range is plenty. Most passenger vehicles, regardless of size or engine power, are used to transport 1 or maybe 2 people. That can be done using very simple and cheap materials, which was my entire point. Using those materials and methods is what will lead to widespread adoption of "electric cars". All the battery electronic cars are unaffordable sports cars / luxury cars intended for wealthy people to show off to their friends, which is fine, but they're never going to be adopted at significant rates on account of cost and our inability to generate enough of the source materials their powertrains require.

If we're dead-set on going back down the energy density totem pole, then very cheap / abundant / simple / recyclable materials is what will be required to do that at scale. That simple fact of engineering immediately excludes all mainstream electro-chemical batteries. Maybe a pure-Iron or Iron-Zinc battery of some kind is a workable solution. If it wasn't affordable and practical to switch to electrification using Lead-acid batteries, then it's even less practical to do that using energy-intensive metals like Lithium. The only dog I have in this fight is a working and affordable car. What it looks like and what powers it is pretty irrelevant to me. I think that much should be obvious from the number of different concepts I've proposed. It's not an object of affection. It's a tool to get work done. If it has four wheels, four doors, four seats, and goes 55mph, then it's a fully functional car. Everything else beyond that is a nice-to-have luxury item.

Calliban · 2023-04-21 17:58:31

I ran a few calcs to see how well a paraffin wax and water-ethanol heat battery would perform as a vehicle propulsion energy source.

Paraffin wax has a heat of fusion of 200KJ/kg and a density of 900kg/m3. Its melting point is 46-68°C. It is relatively cheap and is a commonly used material for making candles. It is non-toxic and has food applications. It is also non-corrosive and broadly compatible with steels.
https://en.m.wikipedia.org/wiki/Paraffin_wax

There higher melting waxes called Gel Wax, and natural waxes like bees wax, but paraffin wax is cheap and available in large quantities from oil refining. Even if we stopped using oil for fuel, we could still refine bitumen to source paraffin wax. So we won't be running out of this stuff anytime soon. I am going to assume a blend of long chain hydrocarbons with melting point 60°C as a starting point for our hot tank. Hot, melted wax is stored in an insulated steel tank, with steel heat exchanger pipes running through it. I am going to begin by assuming 100kg of wax stored in the tank. We can adjust this volume to provide an appropriate range as we go along.

For the cold tank, I am going to assume a water - ethanol mix. It is cheap and can be produced via distillation of fermented sugar. This has high volumetric heat of fusion and the ethanol concentration can be adjusted to achieve any melting point down to -115°C for pure ethanol.
https://www.engineeringtoolbox.com/etha … d_989.html

Heat of fusion of pure ethanol is 106KJ/kg. This compares to 334 kJ/kg for pure water.
https://www.engineeringtoolbox.com/etha … _2027.html

I am going to assume a 50-50 mix by volume ethanol and water. This will melt at -32°C. The density of ethanol is 785.3kg/m3. So a 50-50 volume mix of ethanol and water, will have density 893kg/m3. Of this, 44% will be ethanol by mass. So the heat of melting of the mixture will be approximately: (0.44 x 106 + 0.56 x 334) x 893 = 208,676.24KJ/m3

So far, so good. For the engine working fluid, we idealy want a fluid that has relatively dense gaseous and liquid phases, allowing a compact turbine. It is also advantageous for the working fluid to achieve a high pressure ratio across our chosen temperature range. Propane has molecular weight of 44kg/Kmol. At -32°C, its vapour pressure is 1.6bar(a). At 60°C, vapour pressure is about 23 bar(a). Using propane as working fluid therefore allows a pressure ratio of 14.4.
https://www.engineeringtoolbox.com/prop … _1020.html

The density of propane under standard conditions is 1.5x the density of air. This provides confidence that a propane driven turbine will be compact with high power density.
https://www.engineeringtoolbox.com/propane-d_1423.html

We run our propane heat engine between the hot reservoir (333.2K) and our cold reservoir (241.2K). The Carnot efficiency will be:

n = (Th - Tc)/ Th = (333.2 - 241.2)/333.2 = 27.6%.

I am going to make a sweeping assumption that we can build an engine that can achieve 2/3 of carnot efficiency. That is about the maximum ratio of efficiency of passenger car diesel engines. It would give a conversion efficiency of 18.4%. This means that for one MJ of heat transfered out of the hot tank, some 184KJ of work energy will be harnessed and some 816KJ will be transfered to the cold tank. To provide 1MJ of heat energy, we need some 5kg of wax. To absorb 816KJ of heat, we need 3.49kg of water-ethanol mix. Each 1kWh (3.6MJ) of work energy would require some 166.1kg of hot and cold phase change material. Using the example of the Tesla 3, which consumes 0.14kWh/km, we can deduce that a 50km range would require some 1,186.4kg of hot and cold phase change material.

The total curb weight of a Tesla 3 is only 1610kg, so a battery system of this mass would be very difficult to accomodate.
https://en.m.wikipedia.org/wiki/Tesla_Model_3

There are other phase change materials we could use. We have discussed cryogenic gases before. Aluminium-silicon eutectic melts at about 580°C. We could charge that with a simple heating element. The heat of fusion of aluminium is 396KJ/kg. So this looks more promissing from an energy density viewpoint. But sufficient aluminium would be expensive.
https://www.engineeringtoolbox.com/fusi … _1266.html

For static applications, low mass energy density is less of a problem and wax couod be a useful phase change material for this application. But wax and ice would appear to have insufficient energy density to be useful as mobile energy stores.

Silicon has an extremely high heat of fusion, some 1787KJ/kg.
https://www.engineeringtoolbox.com/fusi … _1266.html

But the problem here is its melting point of 1400°C. Steel has about the same strength as plastacene at these temperatures. And a vat of silicon that hot woukd be difficult to insulate on a car. But this might be a way of powering large ships, maybe even trains.

In terms of a resource sustainable battery, the sodium sulphur battery is probably the best thing we have. Back in the 80s, one company tried to make an EV light goods van piwered by a sodium sulphur battery. Fire proved to be a big problem.

Last edited by Calliban (2023-04-21 18:14:39)

kbd512 · 2023-04-21 18:30:32

Calliban,

Why can't our "cold tank" be the Earth's atmosphere?

641K - Just below the BP of paraffin wax
341K - Just above the MP of paraffin wax

n = (Th - Tc)/ Th = (641K - 341K)/641K = 46.8%

I know we won't achieve 46.8%, but I don't think it has to be quite as bad as dumping heat into a "cold tank" of water-methanol, plus the added weight of that cold tank.

SpaceNut · 2023-04-22 08:39:18

Regenerative breaking comes to mind for increasing the range of the commuter vehicle but at just 55 mph you would be a roadblock for traveling on a highway's which is where I drive the most weekly for work. You are right about just mostly having the 1 or 2 passengers within the vehicle. Solar panels for the surfaces of a vehicle cold also using the air to make cold sink as well for that same range increase. Is dry ice recollected a useable cold sink for this drive system?

I finally found the code 457 for the Subaru that is a emission leak of the fuel system and it's not a gas cap just the filler tube instead.

How to remove
https://youtu.be/lGh3ZWcBjUw

Calliban · 2023-04-22 16:17:11

kbd512 wrote:

Calliban,
Why can't our "cold tank" be the Earth's atmosphere?
641K - Just below the BP of paraffin wax
341K - Just above the MP of paraffin wax
n = (Th - Tc)/ Th = (641K - 341K)/641K = 46.8%
I know we won't achieve 46.8%, but I don't think it has to be quite as bad as dumping heat into a "cold tank" of water-methanol, plus the added weight of that cold tank.

I think it could work. One problem is that as external temperature fluctuates, the pressure ratio across a heat engine would change. But there are lots of media we could use to store heat. Latent heat storage could use aluminium-silicon, which would store about 0.1kWh heat per kg at 580°C.
https://chem.libretexts.org/Ancillary_M … nce_Table)

Here in the UK, storage heaters were developed that stored sensible heat in lumps of iron oxide for space heating. The idea was that nuclear reactors generate 24/7, but demand is lower at night. Night time electricity was cheap, so storage heaters would be fitted with timers that come on at 10pm and switch off at 6am, as demand picks up. Something similar could be used to drive a heat engine powering a vehicle.

kbd512 · 2023-04-22 17:19:19

This vehicle would have a tank containing 1,000kg of paraffin wax. That's 175kWh of stored thermal energy storage at 368C, which is about equal to 4.4 gallons of diesel fuel. A stainless steel heating element inside the paraffin tank, a stainless steel radiator containing multiple thermal power transfer loops using highly pressurized CO2, with the CO2 being used to drive a power turbine. The turbine will be connected to the wheels using a geared transmission. The radiator's multiple loops will be utilized with a flow divider valve connected to the accelerator pedal. Pressing the "gas pedal" to the floor will open the valves so that CO2 flows through all loops of the radiator / heat exchanger loops.

The wax tank will act as the structural "skateboard chassis" for thevehicle, with the mounts for the suspension components being welded to the skateboard for improved rigidity and reducing overall vehicle length. This will be a full-sized 4 seat car, which is important because it needs substantial suspension and tires to support the weight of the vehicle. I estimate a weight somewhere between 4,000 and 4,500lbs, roughly the same weight as a Tesla Model S. I figure on a maximum of about 200hp. Some manner of hybridization is required for acceleration- using built-up heat in a CO2 tank to provide sufficient power for acceleration. The "engine compartment" will be very abbreviated, akin to a van or minivan, since it only contains the radiator, power turbine, and transverse transmission. It won't have a true engine compartment or trunk, therefore more steel can be devoted to the rest of the vehicle chassis without greatly increasing weight.

As is now customary, the vehicle will make extensive use of stamped HSLA steels for greater strength. The power turbine, transmission, and stainless steel radiator loops will be the most expensive parts of the vehicle. However, we're talking about a largely conventional design with a somewhat unconventional energy storage mechanism that is lower-cost than a conventional combustion engine or battery pack.

Is it perfect? Obviously not. It has serious range limitations, it's not a factory-built race car like a Tesla Model S, it's not as energy-efficient as an electro-chemical battery, so it requires more electricity input than a battery as a result, but generating power is clearly far less expensive than storing power in electro-chemical batteries. The vehicle is no more costly than a conventional gasoline powered vehicle to purchase, and this is a key point here. That is the primary reason why battery electronic vehicles have not been purchased in much greater numbers. Price sells vehicles. Very few people can afford to drive a $100,000 Tesla Model S. I'm sure it's a great car, but at the end of the day it's an over-priced and over-complicated sedan with less range than a similar gasoline powered luxury sedan. Anyone who can afford a $100,000 car doesn't care about the cost of gasoline.

kbd512 · 2023-04-22 18:07:00

Calliban,

I'm more interested about knowing why we would need or want a cold tank if the atmosphere provides the ability to dissipate heat using a radiator assembly. For a mobile power solution, why would we use a cold tank of water-methanol in addition to the tank of heat energy storage material when that halves the power-to-weight ratio of the overall solution? What's the underlying reason for having the cold tank?

I know why we had to do that for the LN2 powered train. I specified an open-loop power turbine which would rate-limit the gas expansion / thermal power transfer, so a hot tank was added to improve the thermal power transfer rate and to prevent the power turbine from freezing while expanding the gaseous N2. I then made a second proposal using highly pressurized hot water for that reason, and to eliminate all the energy losses and expense and hazards from dealing with cryogenic liquids. To my knowledge, no car radiator using a heat energy transfer loop has that unique set of problems, though. The "hot tank" is well above atmospheric temperature, so using a gas to remove heat from the hot tank and exchange heat with the much colder atmosphere shouldn't present the same technical problems. There are, of course, other problems, chief amongst them the very low energy density of hot paraffin wax and the significant thermal losses associated with a heat engine.

I can only solve so many problems with a given solution, though. Gasoline and diesel are the best options for powering moving machinery of any significant weight. The paraffin wax solves the extreme pressurization problem associated with using water, it's about $1,200 to fill that tank one time, and the overall energy efficiency is no better than a regular combustion engine. However, this at least presents the possibility of not being forced to burn things for energy. It has no emissions after its built, the overall build process can be much simpler and faster than either a combustion engine or battery electronic vehicle on account of drastically reduced parts count, and the emissions associated with building it are no worse than for a standard combustion engine vehicle.

tahanson43206 · 2023-04-22 18:17:17

For kbd512 re hot wax car design ... I've been scanning your conversation with Calliban, but lost track of where you described the hot wax car design in detail. It is possible you've been designing on the fly as your conversation continued.

There are people who are building an entire city out in the middle of the desert (Saudi Arabia) .... a design for an extremely reliable, long lived vehicle that would move people from the train lines into the city blocks beside the track might be of interest.

There are regions in the US that are so run down they might be considered for total redo with more efficient technology, which your hot wax concept seems to be.

If you decide to create a post just for your design, please install a tag so it will be easy to find.

(th)

kbd512 · 2023-04-22 19:33:07

tahanson43206,

I think I've been remarkably consistent if you search related posts in other threads. I have proposed multiple different ways of doing things. Each one has its own positive and negative aspects. The common theme to my proposals is that none of them are completely unworkable at scale. They give everyone some of what they say they want, which presumes they actually want what they're asking for.

I've yet to see any "extremely reliable and long-lived vehicles" (of any kind) operating in deserts with fine powdery sand. They're spending half a trillion dollars to build a city with no cars, trucks, or busses. That is $13,888.89 for every man, woman, and child living in Saudi Arabia. If I were them, I'd worry a lot more about how to grow enough food and desalinate enough water. Saudi Arabia's poor people are not poor because they have too many or too few cars / trucks / busses / railroads.

Calliban · 2023-04-23 15:26:15

The reasons for including a cold tank containing a phase change material: (1) Assuming the hot tank also contains a phase change material, the heat engine is always working between hot and cold reservoirs with constant temperature. So pressure ratio is constant. (2) Using a cold tank allows a much lower T2 temperature than external air. This allows higher cycle efficiency. (3) If the external environment is used as a cold source, then engine power is limited by the rate at which heat can be dumped into it. That can either be by radiation from the outer surfaces of the car, or forced convection, using air hitting the from of the car to cool a fin radiator. With a cold tank, heat is transfered by conduction across thin walled heat exchanger tubes. This permits higher specific power.

That said, the advantages of cold tank would appear to be weak, maybe too weak to justify its effective dilusion of energy density. One tonne of hot wax at 370°C is a lot of stored heat. Specific heat of liquid wax is 2KJ/kg.K. Between melting point (~70°C) and boiling point (370°C), 1 tonne of wax will store some 167kWh of heat. The median temperature of the wax between melting and boiling is 220°C. Let us assume an effective cold temperature of 300K. Carnot efficiency would average at 39%. If our engine can achieve 2/3 carnot efficiency, then average efficiency would be 26%. This equates to 43.4kWh of work energy. Enough to drive a Tesla 3 some 304km. Our much heavier vehicle with it's 1 tonne wax tank might only manage half that, sat 150km range. That is enough for most of the trips that people make. If we could tolerate a 75km range, then we only need 500kg of wax. Our vehicle might not be any heavier than a Tesla 3.

Last edited by Calliban (2023-04-23 15:56:55)

Calliban · 2023-04-23 16:44:42

Flywheels may turn out to be a better power source for short range vehicles than stored heat for mobile applications.
https://en.m.wikipedia.org/wiki/Flywheel_energy_storage

'Compared with other ways to store electricity, FES systems have long lifetimes (lasting decades with little or no maintenance;[2] full-cycle lifetimes quoted for flywheels range from in excess of 1E5, up to 1E7, cycles of use),[5] high specific energy (100–130 W·h/kg, or 360–500 kJ/kg),[5][6] and large maximum power output. The energy efficiency (ratio of energy out per energy in) of flywheels, also known as round-trip efficiency, can be as high as 90%. Typical capacities range from 3 kWh to 133 kWh.[2] Rapid charging of a system occurs in less than 15 minutes.[7] The high specific energies often cited with flywheels can be a little misleading as commercial systems built have much lower specific energy, for example 11 W·h/kg, or 40 kJ/kg.[8]'

A median lifetime of 1E6 cycles, would allow the flywheel to be charged and discharged 3x aday for 1000 years. For practical purposes, it never wears out. It would easily last for a century in any practical vehicle. Round trip efficiency is high. What's more, it can be charged using mechanical power. Flywheels look promissing.

kbd512 · 2023-04-23 18:29:32

Calliban,

2023 Tesla Passenger Car Curb Weights:
Model S: 4,561lbs to 4,766lbs
Model 3: 3,648lbs to 4,250lbs
Model X: 5,185lbs to 5,390lbs
Model Y: 4,555lbs

The vehicle I'm proposing would be wider and shorter in overall length, with the wax tank acting as a structural member for the vehicle. The curb weight would be largely unaffected.

Tesla is forced to use that GigaPress and other similar silliness due to the sheer cost of the battery and the complexity of vehicle assembly. It's not about weight, it's about assembly time and complexity. The stamped / welded steel chassis was perfectly adequate, as evidenced by the fact that they were previously using stamped / welded sheet steel, but due to the expense and time required to load up the vehicle with the battery and electronics mess, the overall product became too costly.

Engineers like Sandy Munro have mental masturbation sessions over fastener counts because he's probably never had to actually work on a car, and therefore doesn't care about whether or not it's even possible to repair the thing. Trashing an entire car because one part was damaged is not economical for most people. The "solution" wasn't to have a robot install the fasteners faster than a human, it was to use a giant robot to pump out giant Aluminum castings for the wheel wells and then glue those into the chassis of the vehicle so that it didn't have to be welded or secured using a few more bolts. These are the kinds of solutions you get when there's an ideological bent to accomplishing some specific task. All they can see is what they want, and regardless of how nutty the end result is, they'll pursue it anyway. Beyond that, nobody asked the question, "Why did we design the vehicle in such a way as to make assembly so difficult and time-consuming?" The answer is obvious, though. They installed a wildly expensive and complex electro-chemical battery with very large / complex / expensive traction motor(s) and a plethora of electronic sensors running more code than a F-35 stealth fighter jet.

Why did they do all of that?

Ideology is a very powerful force amongst the ideologically self-consumed.

In some ways Tesla is a "learning organization", but still applies too little of Elon Musk's "question everything" principle. To paraphrase what he stated, "You don't end up with some self-limiting design feature that some intern thought was important, but nobody else can figure out why it was done that way or what greater purpose it serves." That's how you end up with $1,000 electronic door handles. That was clearly not about need or overall benefit to the vehicle's design. Someone had an unhealthy obsession with something they thought was "super cool". Fair enough, but the time and expense devoted to the door handles was time and expense not devoted to issues arising from more fundamental design aspects. To wit, "Where are we getting our Copper and Lithium from"?

Speaking of door handle design, if you're going to spend the outrageous sum of money to motorize the silly door handles so they're flush with the body, then just spend a little extra to motorize the entire door and skip the door handles altogether. Either way, if the mechanism ever fails you can't get into the car. If the mechanism is completely contained within the interior of the vehicle, then you have fewer wear components and fewer opportunities for failures. In point of fact, that's what Tesla did on their CyberTruck.

This is the basic layout I had in mind (an Opel concept car from Roman Zenin, university student), in order to reduce vehicle weight:

920381a80f84260c2dafaacda6d58baa--auto-design-automotive-design.jpg

Or maybe something more like this concept car (a bit more traditional in layout):

This uses the space occupied by the doors to house the radiators (mostly empty space), does away with the engine compartment (no longer required), and trunk (perhaps nice to have, but not strictly necessary for a commuter car and none of the hatchbacks have them). If the seats were CFRP and fixed in place, then they'd be easy to take in and out of the vehicle. I would put the radiators along the sides of the car, where the doors used to be, and exhaust the hot air through the rear of the vehicle.

Calliban · 2023-04-24 14:40:29

Are we entering a new Great Depression?
https://www.zerohedge.com/news/2023-04- … depression

M2 money supply is crashing at a rate not seen since the 1930s. Bank lending is contracting.

Calliban · 2023-04-28 11:11:23

How trams are changing France.
https://m.youtube.com/watch?v=5mVza6L3DHU

This is an electrically powered transport system that actually works without unsustainable quantities of battery metals. Mainly because electricity isn't stored. The tram is effectively nuclear powered, drawing energy from the alternator of a nuclear powerplant, through the grid, instantaneously as it is generated. This is how successful electric transportation has always worked. It has its limitations. Like all rail systems, it provides transportation between specific nodes. There can be no variation of route. I would be interested in exploring how tram systems could be adapted for transportation of goods. Passenger transport stops in the wee hours, so presumably the same teacks could be used to shift freight during the night.

Void · 2023-04-28 11:52:04

I am getting internal server error again so I cannot post. Oh well.

Just a bit later..........

France is an interesting alternative to the USA and places that act like the USA. It is sort of inside-out I understand the poor go to the suburbs in France which is the reverse of the USA, and the French did embrace Nuclear very strongly as I recall.

Among places that seem to be able to produce Children are France and Sweden. In the case of Sweden, to some extent it seems to be the use of wealth aid for those who produce children. I am drawing from P. Zeihan materials here.

It seems that in America the Suburbs are considered conducive to the production of "Useful?" new child people. But France apparently does it a different way.

Solutions for each country may not cross over into another, but it is interesting to have a look.

But anyway, linking a tram system to a robot-taxi system could make sense as the trams do not need mobile batteries, but could use stationary batteries or Nuclear.

I don't mind if someone wants to vent a correction for my post here

Done.

Last edited by Void (2023-04-28 11:58:56)

Calliban · 2023-04-28 16:48:04

Recently, we discussed the possibility of using flywheels to power short range cars that can transit towns. The gyrobus was developed to avoid the heavy investment in electric transmission needed by trolley buses. Gyrobuses carried a flywheel, which would power the bus between stops. The steel flywheel carried enough energy to drive the bus up to 10km between stops, over even ground.
https://en.m.wikipedia.org/wiki/Gyrobus

We can build even better flywheels today, made from glass or carbon fibre epoxy composites or high strength polymers. These have much better specific strength than the strongest of steels.
https://en.m.wikipedia.org/wiki/Specific_strength

Flywheels could be applied to tram systems as well. The friction of steel wheels on steel rails can be as little as one tenth of the friction of rubber tyres on asphalt. In addition, a tram has lower frontal area per seat than a typical bus. So a tram propelled by a flywheel might travel as far as 100km between recharges. This should allow tram systems to be constructed without need for continuous electrification. Instead, the tram stops would carry a short section of sliding contact either above or on the track. This should reduce the installation cost of trams, allowing their expansion into lower density urban areas. Valuable in the US I think.

On Mars, atmospheric pressure is very low and gravity is only 38%. A train should require only one third as much energy per tonne-km as an equivelant Earth train. We could power trains using flywheels or hydraulic accumulators. This would be far more energy efficient than any synthetic fuel approach. It is unlikely to offer sufficient range to shift freight on Earth, but could work on Mars.

Last edited by Calliban (2023-04-28 17:14:02)

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