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#126 2022-08-27 14:48:11

kbd512
Administrator
Registered: 2015-01-02
Posts: 5,976

Re: Land propulsion - Tracks, or tires?

Calliban,

With a good Silicon-based corrosion protection coating on the Iron and magnetic levitation, track wear will be zero for a century or more.

As for short-haul movement of people and goods via roads, I think compressed air and much lighter vehicles is the way forward from gasoline and diesel, not batteries and electronics.  I think we've reached the practical limit for better battery technology.  The moment batteries became non-recyclable without expending even more energy than it takes to mine virgin materials, they became impractical.  Yes, technically feasible, but very unfavorable to both the consumer and the environment.

From the late 1950s onward passenger cars became stupidly heavy, and significantly increased power requirements went along with that.  A 100hp V8 engine in the late 1940s or early 1950s was a lot.  There were 4-door sedans with 25hp that would do 55mph.  Passenger cars became hot-rods after that, which is ideal for the race track but not good for the consumer.  A passenger car is not a race car.  I think race cars are cool, but I don't want one as a daily driver, because it comes with race car maintenance requirements.  The smaller British vehicles of the 1950s were the right idea.  With modern technology, we can provide excellent crash protection for lighter vehicles- not the absolute best possible but still truly superb compared to anything from the early 1970s on back.

Modern air tank construction and securing to the vehicle assures that they don't become projectiles in the event of a crash, so I think that problem has been solved to the degree it needs to be.  Carbon fiber turns into spaghetti when ruptured, not shrapnel.  We can power the vehicle's lights and electronics off the air motor or a much smaller air motor while the vehicle idles, so there doesn't need to be any battery onboard, either.  No heavy / resource-intensive / non-recyclable batteries are produced, no fuel is consumed, and compressed air is pretty cheap when industrial compressors produce it.  Did I mention that the vehicle's "air engine" components are repairable using hand tools and do not require any electronics diagnostics?

Your AC system is expanded air from the air engine.  You can have manual steering and brakes with a pneumatic anti-lock system.  The windows can be pneumatic or manual.  You do need an electric heater for northern climates, because the air engine won't produce enough waste heat from piston friction.

Can you imagine going into a service station and the most sophisticated instrument they have is a hand-held multi-meter or voltage tester to assure that power for the lights is at the correct voltage and amperage?  There's no battery tester because there is no battery on board, no $25,000 scan tool is required to diagnose the engine or electronic motor computer, and the vehicle is very light so it's easier to push if it runs out of air.  Fill-up takes no longer than ordinary gasoline powered cars.  The possibility of fire is greatly reduced because no highly-energetic liquid explosive or Lithium-based battery that can achieve arc-welding temperatures from a short-circuit is onboard.

Both batteries and combustion engines will always be "faster" because they can instantly deliver more power, but that comes at a very steep cost to both the consumer and the environment.  We'll still have lots of more suitable applications for batteries and combustion engines, but providing low-cost personal transportation with either is increasingly difficult to achieve.  Long-haul trucks, virtually all types of aircraft designed to fly for more than a half hour, and ships all require combustion engines, period.  No other power source is a suitable replacement, and the aviation industry pushes itself to achieve improved fuel efficiency over time without any government micromanagement.  When the aviation industry continues to use a technology, it's because they've tried everything else and nothing else did the job acceptably well.  However, basing civilized society on simple heat engines consuming solar thermal or nuclear thermal power, pneumatic, and hydraulic technologies is long-term sustainable.

I figure you'll need around $5 worth of compressed air to drive 200 miles or so.  A Tesla has a range of over 300 miles and you pay $17.50 to $20 for a full charge, perhaps as much as $40 in California or a "fast charger" station, so $20 takes you about 800 miles.  I drive about 13,000 miles per year going to work, maybe 15,000 miles total, so $375 per year for air refills.  If you can't come up with $31.25 per month to drive, then maybe driving is not in the cards for you.  Even if it was $50/month, that's inordinately better than what we're spending now, which is around $100/week on gas.  As you know, orders of magnitude have meaning.

We can power the vehicles off of solar thermal power or wind turbines, because air tanks don't care how you fill them up and they don't continuously "self-discharge" the way all batteries do.  The waste heat generated during compression can also be used to heat water, so anyone with a home garage and air compressor could use the waste heat for hot water co-generation.  If you refill your air tank every night, same as with charging batteries, then you don't need to go to gas stations to fill up.  However, it's deeply ingrained in American culture that you take your car to the gas station to fill up, so for homeowners who don't want to pay for or have an air compressor in their garage, this should be an acceptable alternative.

We can use fiber-infused plastics and foam, rather than fabric-based composites, in the vehicle chassis.  We can use composites for the seats and possibly to tune the stiffness of the chassis as well, and re-introduce non-powered steering and brake components.  We can have greatly simplified transmission.  We should commercialize LLNL's "harmonic air motor" design which claims to dramatically increase air motor efficiency and be almost identical to existing piston-type air motors.

Anyway, it's an elegantly simple way to achieve the end goal of moving past gasoline and diesel.  If most of the passenger cars were running on air and some had lawn mower-size engines for range extension, then we could feasibly supply aviation, long-haul semi-trucks, farming equipment, and ships with synthetic fuels while taking an immense amount of pressure off the supply system.

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#127 2022-08-27 16:57:07

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 2,078

Re: Land propulsion - Tracks, or tires?

Makes sense.  Kris DeDecker wrote an article on small scale compressed air energy storage in his Low Tech magazine.  CAES is far more sustainable than battery storage.  The problem is poor cycle efficiency, low energy density and high capital cost of tanks.  But from a resource sustainability perspective, CAES beats any kind of battery.  Low cycle efficiency can be mitigated if compression heat can be put to another use, as you identified.  For vehicles, CAES may work better in a hybrid, where engine waste heat can maintain air temperature as it expands.  As stationary storage, carbon steel tanks have almost infinite stress cycle.  We still have functional steam engines that were built over a century ago.  Although expensive, these tanks will last for many decades.  On a large scale, pre-stressed cast iron or concrete storage vessels have a reduced capital cost.

In the home, or in many buildings, both compression heat and expansion cold can be put to use.  So efficiency could be close to 100%.  We could in fact build expansion turbines into freezer units, allowing the expansion cold to be put to use.

A while back, I looked into storing energy in partial vacuum, by pumping water out of a sealed vessel.  The problem here is extremely low energy density.  If we are reducing pressure from 1 bar to 0.5 bar, then the vacuum will store some 50KJ per cubic metre.  The advantages are: (1) Good storage efficiency, on a par with li-ion batteries; (2) Forces on the vessel are all compressive, so low cost concrete or even rammed earth can be used to build it; (3) Vacuum tanks never wear out.

But to store even 1kWh would need a tank volume of 72m3.  I felt that the concept may have niche applications, but the pathetically low energy density is a severe limiting factor.  But if you build a house with a vacuum energy store built into it, then it should last for centuries.  It would be useful for short term load balacing, in situations where power supply is steady but equipment demands heavy peak loads for short periods.  Washing machine spin cycles, for example.  A 1kWh store, could provide mechanical power of 60kW for 1 minute.  If you had a home solar system that was producing an average of 500W, something like this would allow you to power much higher loads for short periods.   I may develop the idea some more at some point.  Useless on Mars, for obvious reasons.

Last edited by Calliban (2022-08-27 17:34:43)


"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

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#128 2022-08-27 19:34:45

kbd512
Administrator
Registered: 2015-01-02
Posts: 5,976

Re: Land propulsion - Tracks, or tires?

Calliban,

I've simply noted that vehicle weight has slowly trended towards absurdity for both passenger cars and trucks.  A Tesla Model 3 weighs as much as my 2012 Chevy Silverado 1500 regular cab.  That's nuts.  GM has also created experimental variants of the Silverado that were significantly lighter than the all-steel models, and would not have required as much power to move them as a result.  The GM Hummer EV weighs over 9,000lbs, which is as much as some of the smaller semi-tractors from the 1950s.  Basically, this trend towards heavier vehicles cannot continue unabated forever.

Check out the curb weights on those steel beasts:
GM Heritage Center - 1959 Chevrolet Truck

Most of them aren't as heavy as the GM Hummer EV.

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#129 2022-09-02 12:12:28

Mars_B4_Moon
Member
Registered: 2006-03-23
Posts: 4,330

Re: Land propulsion - Tracks, or tires?

Canada might be getting a 1,000 km/h vacuum-tube train
https://www.ctvnews.ca/sci-tech/canada- … -1.6051975
A Canadian company has unveiled plans for a fully electric train-style vehicle which could travel at 1,000 kilometres per hour

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#130 2022-09-06 10:49:04

Mars_B4_Moon
Member
Registered: 2006-03-23
Posts: 4,330

Re: Land propulsion - Tracks, or tires?

Hyundai Motor, Kia and 6 research institutes to develop lunar exploration vehicle
https://koreajoongangdaily.joins.com/20 … 30511.html
Hyundai Motor and Kia will form a council with six government research institutes to jointly develop a vehicle for lunar exploration.

The companies and institutes signed an agreement Wednesday promising to jointly conduct research on the technologies to make a vehicle that can explore the surface of the moon. The six state-run institutes are the Korea Astronomy and Space Science Institute, the Electronics and Telecommunications Research Institute, the Korea Institute of Civil Engineering and Building Technology, the Korea Aerospace Research Institute, the Korea Atomic Energy Research Institute and the Korea Automotive Technology Institute.

The council will start its research as early as August. It will also come up with specific strategies for how to operate the vehicle on the moon, Hyundai said.

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#131 2022-09-21 15:01:27

Mars_B4_Moon
Member
Registered: 2006-03-23
Posts: 4,330

Re: Land propulsion - Tracks, or tires?

Fehmarn Belt Link: Are the benefits of the world's longest underwater rail tunnel worth the damage?

https://uk.style.yahoo.com/news/fehmarn … 40746.html

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