Transit comparisons

[WALTER BREWER]

Compare Hdroloop with same capacity  ordinary LRT, say in per-seat-mile:

                    Total energy,

                    Total emissions, inc co2,

                     Cost including capital,

                     Construction per mile,

Assume ~20 miles total, same number start/stops.

 

Walt Brewer

[WALTER BREWER]

[Jerry Roane]

Walt

I did a search on Hdroloop Google came up with Hyperloop.  Any comparison between modes must include accurate ridership in practice over a few years of use.  Total emissions must include upstream emissions of the power source to be valid.  Assumptions on starts and stops would need to match daily commutes in practice where something like Hyperloop would be commuting hundreds of miles to work and LRT would be commuting tens of miles.  Hyperloop must not stick with the circular cross section car or they will need to shut that down.  

Jerry Roane 

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[WALTER BREWER]

Splash, splash! I'm all wet...Hyperloop

Walt Brewer

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[WALTER BREWER]

Believe it or not I know about most of those functions, but where are some numbers.

The 20 or so mile case is coming up.

Walt Brewer

[Jerry Roane]

Walt

The information on Hyperloop and Hyperloop-One is all over the map.  I saw the following horsepower numbers:

28,000 hp 3000 hp 134 hp 4366 hp  3131 hp from the Internet

Obviously the journalists never lead with the engineering but with the hype and they typically tend to lean towards the personalities rather than the devices.  

I did find a pressure that Elon Musk mentioned of around 1 millibar  roughly equal tot the air pressure at 100,000 feet altitude.  What is more important is the air density of ,33 - ρ -    (10^-4 slugs/ft³)

For comparison air density at sea level is 23.77 - ρ -  (10^-4 slugs/ft³)

The big claim of Hyperloop is all about the air density difference.  Problem is the tube is not at 100,000 feet so it is in the atmosphere at 14.7 psi.  It takes horsepower to constantly draw down the vacuum.  Those turbines get more and more inefficient as the vacuum improves.  I have no idea how much horsepower is going to be required per full passenger seat for many reasons.  Ridership is the biggest variable as with all big box transit schemes.  power to evacuate the tube while loading a pod is totally ignored in the hype.  It is going to be substantial not just for energy but for time to load a pod.  I do not think Hyperloop is going to work in a location like the Boston subway with stops every few blocks.  The pump down of each pod loading is going to waste too many people's time.  Sealing an 11 foot diameter loading hole is a crazy engineering challenge.  How do you design a vacuum seal that is that large and still maintains a 1 millibar.  Wear and scratches in the rubber or Teflon will be really expensive to maintain.  Having worked in the semiconductor industry with high vacuum manufacturing of MEMS sensors, I am skeptical of the ability to evacuate an 11 foot diameter tube.  

The speed I found on the Internet was 220 mph not 760 mph.  Those two power levels are worlds apart.  The suspension at 760 mph is going to be more than just an air bearing gap of .05".  Any touch down of steel on steel at 760 mph will create incredible heat.  Again I am skeptical of the ability to make the track that straight in real dirt without using TriTrack patented features of computer driven dynamic track support.  

Thermal expansion of this tube across a desert will be tough to achieve without the tube being flexible.  The top of the tube will be in full sun and the bottom of the tube is in full shade.  That will tend to bow each tube section into a macaroni shape per track section.  At 760 mph the suspension will need to absorb that wiggle without generating much heat.  On dirt bike motorcycles they have suspension coolers to expel the heat from going over rough mud and dirt.  A bus sized pod inside a tube is going to need to expel the heat from the wiggling suspension.  The 100,000 foot altitude atmosphere is not going to cool anything.  Heat generated in the suspension and braking will need to be held inside the pod and dumped at each stop.  I have seen nothing to indicate that they have a thermal storage feature in the Hyperloop.  The motor stators are going to need to be cooled with conduction but the rotor (the pod) won't have anyplace to dump the heat without thermal storage being part of the payload.    Thermal storage is typically heavy.  

LRT likewise does not publish their energy cost per served passenger mile.  They don't even mention the electric bill to power the LRT line because it is so high and ridership so low.  Worse than that it is extremely variable making it hard to publish a real answer to the question.  

I am working on a similar concept with the DOE about switching trucking freight to TriTrack freight.  The pollution calculation is easy since TriTrack is zero pollution.  Trucks emissions are well documented and significant. The amount of diesel and gasoline the US wastes money on is equal to the record trade imbalance in the world.  No other time in recorded history has a nation owed more than us.  If we switch trucking and passenger cars to sunshine from fossil fuel then we can sell our energy to the rest of the world who will not be converting.  

Jerry Roane