Gleaming the Tube — a brief examination of pneumatic propulsion technology for human and cargo transport purposes.

I’ve been engaged in conservation efforts in the Energy and Transport sectors of various Pacific Island countries in varying capacities over the last few years. I’ve come across some material during my thesis research which may not necessarily be useful for archipelagic nations, but should help people better understand the Hyperloop concept put forth by Elon Musk (who has gone from a promising disruptive tech entrepreneur at the peak of the industry to unhinged megalomaniac in the time since I initially wrote this article.) In the meantime, these entries from MIT, Delft, U of Wisconsin, Virginia Tech, and UC Irvine should provide you with all the forward thinking design you can process in one evening. If you’re less interested in delving deep, find a brief summary of each entry in this piece over at The Verge.

I know many people aren’t necessarily interested in paying the utmost of attention to the current cutting edge in transport technology, and that’s why it’s a huge part of my academic and professional work, so I can begin to summarize the most innovative and efficient material however I can.

I’ve been looking into a variety of different public transportation models for increased commuter efficiency, and I think a brief look at vacuum systems and pneumatic transport should be useful for many out there trying to envision a likely low-carbon future for cross-continental travel. The recurring costs and continuously growing rate of emissions in the air transport sector will need to be mitigated, and this is one path towards alleviating the passenger and cargo burden created by an economy used to high-speed transit.

The idea of using a pneumatic tube for transportation technology is not a new concept. Speculation on the possibilities of vacuum-driven conveyance was brought from the theoretical realm into practical application prior to the advent of the railway. Even the Wikipedia entry on the mechanism lays out the lost opportunities in the 20th Century quite succinctly:

“In the 1960s, Lockheed and MIT with the United States Department of Commerce conducted feasibility studies on a vactrain system powered by ambient atmospheric pressure and “gravitational pendulum assist” to connect cities on the country’s East Coast. They calculated that the run between Philadelphia and New York City would average 174 meters per second, that is 626 km/h (388 mph). When those plans were abandoned as too expensive, Lockheed engineer L.K. Edwards founded Tube Transit, Inc. to develop technology based on “gravity-vacuum transportation”. In 1967 he proposed a Bay Area Gravity-Vacuum Transit for California that would run alongside the then-under construction BART system. It was never built.”

We have missed out on the opportunity to reduce flight and infrastructure construction and repair costs to the highway system by neglecting the well-documented and proven potential for high-speed, low energy sealed-chamber vacuum airlock transport systems. As George Medhurst laid out in 1812, “a large, stationary steam powerplant could produce enough pressure to propel a carriage to an average swiftness of 50 miles per hour, with a fuel efficiency of 4.2 miles per coal-bushel.”

For those of you not interested in doing the energy conversions, a bushel of coal is 80lbs. One kilowatt hour (1kWh) is the unit customarily used for measuring electrical energy consumption at a residential or commercial level — 1.04lbs of coal will yield 1kWH.

This means 0.96kWH per pound of coal, which, depending on the grade of coal carbon content and complete combustion, according to the U.S. Energy Information Administration, can range from, “60 percent for lignite to more than 80 percent for anthracite.” So as the EIA states, if coal composed of 78% carbon emits 204.5 pounds of carbon dioxide per million Btu (British Thermal Units) when completely burned, “complete combustion of 1 short ton (2,000 pounds) of this coal will generate about 5,720 pounds (2.86 short tons) of carbon dioxide.”

So in 1812, theoretical calculations had already demonstrated the capacity for coal-powered steam plants to send a passenger car at 50mph for 4.2 miles along a pneumatic track with 71.5lbs of associated carbon dioxide emissions. Now, estimates show even a vehicle achieving an average of 21 miles per gallon of petroleum, and this is in a decentralized, vehicle-specific drive train lacking the efficiency benefits of energy generated at scale, would emit 4.62lbs of carbon in the same distance.

To shift the context back to electrified energy units, it would take 76.8kWh to move a passenger car using components from an 1812 design 4.2 miles in a vacuum system. “A 1.65-MW turbine can produce more than 4.7 million kWh in a year — enough to power more than 470 households.” This indicates ONE commercial wind turbine, appropriately sited, could power at least 61,197.91 miles of transit per year, or 167.67 miles per day — approximately equivalent to the round trip distance between New York City and Philadelphia. To drive the same distance in the theoretical average car mentioned above, it would require 97 miles of road use, emitting approximately 21lbs of CO2.

There is no reason to think this technology will stay relegated to the shelves of science fiction given the hybridized benefits of various other transit modes, including the speeds of air carriers and efficiency surpassing modern rail. Looking back to 1967, I’d been trying to find a copy of the announced Bay Area gravity-vacuum Transit plans, which led me to the full proposal (which require an account with Scientific American to retrieve.) I have yet to receive my site license for the archives, so a Part 2 to this brief piece may be in order soon. In the meantime, as you head to work tomorrow or plan your next trip, I advise you take a moment to think about all the means of reaching your destination you may not be able to enjoy because of the long-running history of motivating forces in regional transport markets.

Additional Sources:

1. https://web.archive.org/web/20110927014656/http://dsc.discovery.com/convergence/engineering/transatlantictunnel/interactive/interactive.html
2. http://onlinelibrary.wiley.com/doi/10.1002/tt.v10:2/issuetoc
3. http://www.tribology-abc.com/abc/hybrid.htm
4. http://www.google.ch/patents/US6048168
5. https://www.researchgate.net/publication/305731891_Thermal_Characteristics_of_Water-Lubricated_Ceramic_Hydrostatic_Hydrodynamic_Hybrid_Bearings
6. https://www.researchgate.net/publication/257545389_Design_and_preparation_of_high-performance_alumina_functional_graded_self-lubricated_ceramic_composites
7. https://www.researchgate.net/publication/223642667_Experimental_study_of_the_effect_of_microtexturing_on_oil_lubricated_ceramicsteel_friction_pairs
8. https://www.researchgate.net/publication/287328166_Development_of_Oil_Lubricated_CeramicSteel_Friction_Pairs_at_High_Sliding_Speeds?ev=srch_pub
9. http://www.america2050.org/upload/2011/12/EconomicGeographyofMegaregions2007.pdf