View source for Compressed-air vehicle

{{Short description|Car that uses pneumatic motors}}

A '''compressed-air vehicle''' ('''CAV''') is a transport mechanism fueled by tanks of pressurized [[atmospheric]] [[gas]] and propelled by the release and expansion of the gas within a [[pneumatic motor]].

CAV's have found application in [[torpedoes]], locomotives used in situations where standard locomotives are a hazard, and early prototype [[submarines]].

Compressed-air vehicles operate according to a [[thermodynamic process]] in which air cools down when expanding and heats up when being compressed, resulting in unwanted energy losses. However, with recent developments in [[isothermal]] [[compressed air energy storage]] (ICAES) plants, [[compressed air storage]] has reached 3.6 MJ/m<sup>3</sup> and four times the [[capacity factor]] of [[lithium-ion]] batteries with 2.7 MJ/kg.<ref name="semanticscholar.org">{{cite journal|title=Thermal analysis of near-isothermal compressed gas energy storage system |year=2016 |publisher=semantic scholar |doi=10.1016/J.APENERGY.2016.07.059 |s2cid=113436358 |last1=Odukomaiya |first1=Adewale |last2=Abu-Heiba |first2=Ahmad |last3=Gluesenkamp |first3=Kyle R. |last4=Abdelaziz |first4=Omar |last5=Jackson |first5=Roderick K. |last6=Daniel |first6=Claus |last7=Graham |first7=Samuel |last8=Momen |first8=Ayyoub M. |journal=Applied Energy |volume=179 |pages=948–960 |bibcode=2016ApEn..179..948O |osti=1324083 |doi-access=free }}</ref> In 2020 there were developments published by Dr. Reza Alizade Evrin from [[Ontario Tech University]]<ref name="Compressed air cars for urban transportation">{{cite web|url=https://www.advancedsciencenews.com/compressed-air-cars-for-urban-transportation/ |title=Compressed air cars for urban transportation |date=7 September 2020 |publisher=advancedsciencenews |accessdate=2020-09-07}}</ref><ref name="Experimental investigation of a compressed air vehicle prototype with phase change materials for heat recovery">{{cite journal|title=Experimental investigation of a compressed air vehicle prototype with phase change materials for heat recovery |year=2020 |publisher=onlinelibrary.wiley |doi=10.1002/est2.159 |last1=Evrin |first1=Reza Alizade |last2=Dincer |first2=Ibrahim |journal=Energy Storage |volume=2 |issue=5 |s2cid=219020514 |doi-access=free }}</ref> with an [[isothermal compressed-air vehicle]] prototype that uses [[low pressure|low-pressure]] air tanks and exhaust air recovery to power a paraffin [[heat exchanger]] system with a global [[energy efficiency (physics)|energy efficiency]] of 74% and a driving range of {{cvt|140|km|mi}}. This efficiency and range can be increased by using storage tanks as vehicle structure, high-pressure tanks, new rotary engines, and a more efficient heat exchanger.

Compressed-air propulsion may also be incorporated in hybrid systems, such as with [[battery electric propulsion]]. This kind of system is ''hybrid pneumatic–electric'' propulsion. [[Regenerative braking]] can also be used in such systems.

== Compressed-air engines ==
In principle, any [[pneumatic motor]] can be used for a compressed-air vehicle, but some engines were specifically developed for this application and/or have specific advantages.

=== Di Pietro engine ===
[[File:Di Pietro Engine Animation2.gif|thumb|Dipietro eccentric shaft, rotary vane air engine]]

There have been several dubious claims with undisclosed information.
However, the "Di Pietro" engine has been partially tested with [[CAD]] and [[finite element analysis]] program and published in scientific papers by [[Jarosław Zwierzchowski]] from [[Lodz University of Technology]] in 2017,<ref>{{cite web|url=https://www.researchgate.net/publication/316884692 |title=Design type air engine Di Pietro |date=2017-07-18 |accessdate=2017-10-13}}</ref> which is an eccentric shaft vane motor that uses low air pressure.

=== Liquidpiston ===
Another recent engine that could be adapted to compressed air is the [[Liquidpiston]] rotary engine.<ref name="Development of a Small Rotary SI">{{cite web|url=https://www.researchgate.net/publication/290334362 |title=Development of a Small Rotary SI/CI Combustion Engine |date=2014-07-18 |accessdate=2014-10-13}}</ref>

== Compressed-air tanks and collision safety ==

{{Main|Compressed-air tank}}
The tanks must be designed to safety standards appropriate for a [[pressure vessel]], such as [[ISO 11439]].<ref>{{cite web|url=http://www.iso.org/iso/catalogue_detail?csnumber=33298 |title=Gas cylinders – High pressure cylinders for the on-board storage of natural gas as a fuel for automotive vehicles |publisher=Iso.org |date=2006-07-18 |accessdate=2010-10-13}}</ref>

The pressure vessels or air storage tanks that can be used in compressed-air vehicles can be made for low pressure ({{cvt|9|atm|psi}}) or high (more than {{cvt|240|atm|psi}}), and can be made of composite materials like thermoplastic and fiber-reinforced thermoplastics,<ref name="compositesworld.com">{{cite web|url=https://www.compositesworld.com/articles/thermoplastic-composite-pressure-vessels-for-fcvs |title=Thermoplastic composite pressure vessels for FCVs |publisher=compositesworld.com |date=2015-02-01 |accessdate=2015-02-01}}</ref><ref name="plastics.gl">{{cite web|url=https://www.plastics.gl/automotive/high-pressure-gas-tanks-in-thermoplastic-composites/ |title=High pressure gas tanks in thermoplastic composites |publisher=plastics.gl |date=2014-05-01 |accessdate=2014-05-01}}</ref> that means that the price can drop by using recycled or biobased thermoplastics using [[rotational molding]] and they are much lighter than lithium-ion batteries and 70% lighter compared to steel tanks, also they have more lifespan and don't need much maintenance.

To reduce vehicle weight further the air tanks can be used as structural storage so the tank is the main part of the vehicle chassis while using appropriate impact isolation, however fiber reinforced thermoplastic tanks only have ruptures in case of collision and don't explode. Some advances in pressure vessels for vehicles have been developed for hydrogen vehicles with high compression pressure vessels. Automobile designer Hyundai states:<ref name="hyundaimotorgroup">{{cite web|url=https://news.hyundaimotorgroup.com/Article/Hydrogen-Tank-Safety-Proven |title=OHydrogen Tank: Safety Proven (OA-ICAES) System  |publisher=hyundaimotorgroup |accessdate=2019-07-13}}</ref><blockquote>Hydrogen tanks require ‘High Strength’ to prevent rupture and ‘High Stiffness’ for durability. Strength is defined as the level of resistance to an influence of an external force. Stiffness is the level of resistance maintaining its original shape. The carbon fiber materials used in making hydrogen fuel tanks is as light as a plastic but has six and four times the strength and stiffness of steel, respectively. “When a bullet penetrates a hydrogen tank, it does not explode. Instead, hydrogen leaks out through the bullet hole. In a standard collision test, not even a tiny amount of hydrogen was detected because none had leaked out.</blockquote>

== Compressed-air production, storage and energy efficiency and density ==

[[Compressed air]] has a low [[energy density]], however near-isothermal compressed air storage [[Compressed air energy storage|ICAES]] can reach 3.6 MJ/m<sup>3</sup> and has almost four times the energy density of [[lithium-ion]] batteries with 2.7 MJ/kg.<ref name="semanticscholar.org"/> 

Compressed air can be produced by attaching an [[air compressor]] or [[hydraulic pump]] to a wind turbine<ref name="fieldlines.com">{{cite web|url=https://www.fieldlines.com/index.php?topic=148883.0 |title=Wind Turbine Air Compressor  |accessdate=2015-07-13}}</ref><ref name="researchgate.net">{{cite web|url=https://www.researchgate.net/publication/320288204 |title=Open Accumulator Isothermal Compressed Air Energy Storage (OA-ICAES) System  |accessdate=2018-07-13}}</ref> or using river, tidal, wave [[hydropower]] turbine with only a conversion from mechanical to pneumatic energy, eliminating electricity from the loop which gives higher efficiency overall.

Additionally, there is the possibility of using thermal energy with a parabolic or [[Fresnel lens]] [[solar concentrator]] to power a thermal [[Stirling engine]] to move the compressor or pump, as [[solar-powered Stirling engine]]s are more efficient than solar steam and photovoltaic.{{Citation needed|date=January 2024}}

== Emissions ==
Since the compressed air is filtered to protect the compressor machinery, the air discharged has less suspended dust in it, though there may be carry-over of lubricants used in the compressor or engine. This can be mitigated by using oil-free air compressors.

== Resource consumption ==
The recent developments of composite [[pressure vessels]] and pneumatic components mean that compressed-air vehicles can be part of the [[circular industry]] with [[Bioplastic|biobased]] or [[recycled]] components. Also, by cutting electric energy from the loop there is no need for an electric grid and the metals used like copper, iron in magnets, etc.

== History ==
[[File:CompressedAirLocomotive Section1 AdolpheBraun1811to1877.jpg|thumb|Gotthardbahn{{dash}}pneumatic locomotive with attached pressure container<ref>Braun, Adolphe: Luftlokomotive in "Photographische Ansichten der Gotthardbahn", Dornach im Elsass, ca. 1875</ref>]]
Compressed air has been used since the 19th century to power [[mining|mine]] [[locomotives]] and trams in cities such as Paris (via a central, city-level, [[Compressed air energy storage#History|compressed air energy distribution system]]), and was previously the basis of naval [[torpedo]] propulsion.

During the construction of the [[Gotthardbahn]] from 1872 to 1882, pneumatic locomotives were used in the construction of the [[Gotthard Rail Tunnel]] and other tunnels of the Gotthardbahn.

In 1903, the Liquid Air Company located in London, United Kingdom, manufactured several compressed-air and liquified-air cars. The major problem with these cars and all compressed-air cars is the lack of torque produced by the "engines" and the cost of compressing the air.<ref>{{cite web|url=http://www.didik.com/ev_hist.htm |title=History and Directory of Electric Cars from 1834 to 1987 |publisher=Didik.com |accessdate=2009-09-19}}</ref>

Since 2010, several companies have started to develop [[#Developers and manufacturers|compressed air cars]], including hybrid types that also include a petrol-driven engine; none has been released to the public, or have been tested by third parties.{{Citation needed|date=January 2024}}

== Advantages ==
{{More citations needed|date=March 2010|reason=every claim needs a reliable source}}
{{Cleanup|date=January 2024|reason=This article has a number of grammatical errors.}}
With the [[Energy efficiency (physics)|efficiency]] of using wind turbines to power compressors or pumps, there is a single conversion of mechanical to pneumatic or hydraulic energy.<ref name="researchgate.net" /> Also, by powering the compressor with a [[Stirling engine]] using a parabolic or [[Fresnel lens]] [[solar concentrator]], there is [[thermal energy|thermal]] to [[mechanical energy]] conversion. Lastly, by using a phase change material in the [[heat exchanger]] heated with [[concentrated solar power]] there is only solar thermal energy involved.

The most efficient compressed-air vehicle as of 2020 is an isothermal prototype at 74%,<ref name="Compressed air cars for urban transportation"/><ref name="Experimental investigation of a compressed air vehicle prototype with phase change materials for heat recovery"/> which is similar to the 73-90% of [[electric vehicles]] using [[lithium-ion]] batteries.

Compared to lithium-ion, isothermal [[compressed air energy storage]] (ICAES) can be at least 2.7 MJ/kg or 3.6 MJ/m<sup>3</sup>, 4 times <ref name="semanticscholar.org"/> of lithium-ion batteries, which can be improved with high-pressure vessels and heat exchanger systems.

Resources, compressed air technology can be adapted to [[renewable energy]] and [[circular industry]] with [[Bioproduct|biobased]] or recycled composites and so compared to [[electric vehicle]]s they can be exempt from finite mineral resources or toxic processes used in [[Electric battery|battery]] and [[electric motor]] manufacturing and also from the electric grid use.<ref name="compositesworld.com"/> Refilling is possible in almost any place or with onboard equipment. It may take advantage of other renewable sources such as wind, [[solar power]] or river, tidal, wave [[hydropower]] to move an [[air compressor]], [[hydraulic pump]] or [[Stirling engine]].

The [[structural weight]] of composite [[pressure vessel]]s is low relative to [[lithium-ion]] [[Electric battery|batteries]] and also to steel tanks (70% lighter),<ref name="plastics.gl"/> which can be reduced by using the tanks as vehicle chassis structures with appropriate impact isolation. The [[wheel hub motor]] rotary engines are also light weight.

They have [[energy synergy]] with the available pneumatic energy, so all vehicle [[mechatronics]] systems can be powered by small air motors, and the vehicle can also use [[active pneumatic suspension]], [[pneumatic steering]] or pneumatic shock absorption bumpers,<ref>{{cite web|url=https://www.researchgate.net/publication/340022516 |title=Automated Pneumatic Bumper For Vehicle Safety |date=2012-05-01 |accessdate=2014-05-01}}</ref> and provide [[air conditioning]] or climate control using the low temperature created during air expansion. [[Energy recovery]] systems with [[regenerative suspension]] and [[regenerative braking]] produce [[low pressure compressed air]] to be stored in an additional [[pressure vessel]].

There is little noise from [[pistonless rotary engine]]s while using compressed air, which can also being soundproofed because the low temperature in which it works.

There is no [[fire hazard]], which makes it one of the few [[transportation]] systems that cannot produce spontaneous or after-collision fire or explosions as with petrol, ethanol, hydrogen and also battery vehicles.

== Disadvantages ==

The [[energy density]] of [[compressed air]] is low compared to [[liquid nitrogen]] or [[hydrogen]], and the [[Energy efficiency (physics)|energy efficiency]] of [[compressed air engine]] compared to micro [[gas turbine]] with adequate [[soundproofing]] that can be used in hybrid gas turbine-electric motor vehicles with a mixture of compressed air, liquid nitrogen or hydrogen (previous [[gas turbine vehicle]]s have used a setup for speed, rather than efficiency consisting in a large noise gas turbines connected to the transmission) since the gas turbine (which are used in [[thermal power plants]] due to its [[efficiency]]) outperforms [[pistonless rotary engine]]s, however the production of [[compressed air]] is more [[energy efficiency (physics)|energy efficient]] and so requires less [[wind power]] and infrastructure and also there is a loss of efficiency from [[gas turbine]] to [[Electric generator|generator]] and to [[electric motor]].

While batteries can somewhat maintain their voltage throughout their discharge and chemical fuel tanks provide the same power densities from the first to the last litre, the pressure of compressed air tanks falls as air is drawn off, reducing available power.

== Possible improvements ==

It may be possible to store compressed air at lower pressure using an absorption material within the tank. Absorption materials like [[Activated carbon]],<ref>{{cite web|url=https://www.nsf.gov/news/news_summ.jsp?cntn_id=108390 |title=National Science Foundation (NSF) News – From Farm Waste to Fuel Tanks – US National Science Foundation (NSF) |publisher=nsf.gov |accessdate=2010-10-13}}</ref> or a [[metal organic framework]]<ref>{{cite journal|doi=10.1021/ja0771639 | pmid=18163628 | volume=130 | issue=3 | title=Metal-Organic Framework from an Anthracene Derivative Containing Nanoscopic Cages Exhibiting High Methane Uptake | journal=Journal of the American Chemical Society | pages=1012–1016 | author=Ma Shengqian| year=2008 | doi-access= | bibcode=2008JAChS.130.1012M }}</ref> is used for storing [[compressed natural gas]] at {{cvt|500|psi|atm}} instead of {{cvt|4500|psi|atm}}, which amounts to a large energy saving.

== Vehicles ==
[[File:American compressed air locomotive used in boring the Rove Tunnel Scientific American 1916-11-25.jpg|thumb|Compressed-air locomotive used in boring the [[Rove Tunnel|Rove canal tunnel]] in France]]
{{Update|section|date=February 2013}}

=== Production cars ===
{{Main|Compressed-air car}}
Several companies are investigating and producing [[prototype]]s including hybrid compressed-air/gasoline-combustion vehicles.  As of August 2017, none of the [[#Developers and manufacturers|developers]] have yet gone into production, although Tata has indicated they will begin selling vehicles from 2020<ref>{{cite web|title=Tata Motors' air-powered car project still on, to be launch ready in 3 years|url=http://www.autocarpro.in/news-national/tata-motors-air-powered-car-project-launch-23659|website=Auto Car Professional|accessdate=24 August 2017}}</ref> and [[Motor Development International|MDI]]'s US distributor Zero Pollution Motors says production of the [[AIRPod]] will commence in Europe in 2018.<ref>{{cite web|url=http://zeropollutionmotors.us/|website=Zero Pollution Motors|accessdate=25 August 2017}}</ref>

=== Experimental cars and bikes ===
In 2008, a compressed air and [[natural gas]] powered vehicle designed by engineering students at [[Deakin University]] in Australia was the joint winner of the [[Ford Motor Company]] T2 competition to produce a car with a {{cvt|200|km|mi}} range and an estimated cost of less than $7,000.<ref>{{cite web|title=Deakin Green Car Showcased in Ford Global Challenge|url=http://www.deakin.edu.au/about-deakin/media-releases/articles/2008/deakin-green-car-showcased-in-ford-global-challenge|website=Deakin University|accessdate=25 August 2017}}</ref><ref>{{cite web|title=Ford Model T Design Challenge: the winners|url=http://www.carbodydesign.com/archive/2008/10/03-ford-model-t-design-challenge-winners/|website=Car Body Design|accessdate=25 August 2017}}</ref>

Australian company Engineair has produced several vehicle types - moped, small car, small carrier, go-cart - around the rotary compressed air engine created by [[Angelo Di Pietro (inventor)|Angelo Di Pietro]].

A compressed-air powered motorcycle, called the Green Speed Air Powered Motorcycle was made by Edwin Yi Yuan, based on the Suzuki GP100 and using the Angelo Di Pietro compressed-air engine.<ref>{{Cite web|url=http://www.ecofriend.org/entry/eco-bikes-green-speed-air-powered-motorcycle-aims-to-smash-land-speed-record/|archiveurl=https://web.archive.org/web/20110218141158/http://www.ecofriend.org/entry/eco-bikes-green-speed-air-powered-motorcycle-aims-to-smash-land-speed-record/|url-status=dead|title=Green Speed Air Powered Motorcycle|archivedate=February 18, 2011|accessdate=May 29, 2020}}</ref>

Three mechanical engineering students from [[San Jose State University]]; Daniel Mekis, Dennis Schaaf and Andrew Merovich, designed and built a bike that runs on compressed air.  The total cost of the prototype was under $1000 and was sponsored by Sunshops (on the Boardwalk in [[Santa Cruz, California]]) and NO DIG NO RIDE (from [[Aptos, California]].). The top speed of the maiden voyage in May 2009 was {{cvt|23|mph|km/h}}.
While their design was simple, these three pioneers of compressed air powered vehicles helped pave the way{{citation needed|date=April 2018}} for French automaker Peugeot Citroën to invent a brand new air-powered hybrid. The 'Hybrid Air' system uses compressed air to move the car's wheels when driving under {{cvt|43|mph|km/h}}. Peugeot said the new hybrid system should get up to 141 miles per gallon of gas. Models were claimed to start rolling out as early as 2016 [http://screen.yahoo.com/hybrid-car-runs-air-001013615.html] {{Webarchive|url=https://web.archive.org/web/20130129134636/http://screen.yahoo.com/hybrid-car-runs-air-001013615.html |date=2013-01-29 }}. However, the head of the project left Peugeot in 2014, and in 2015 the company said it had been unable to find a partner to share the development costs, effectively ending the project.<ref>{{Cite web|url=https://www.lesechos.fr/2015/01/psa-la-revolution-de-lhybrid-air-naura-pas-lieu-190742|title=PSA : la révolution de l'Hybrid Air n'aura pas lieu|date=Jan 11, 2015|website=Les Echos|accessdate=May 29, 2020}}</ref>

"Ku:Rin" named air-compressed three-wheeler vehicle was created by [[Toyota]] in 2011. The specialty of this vehicle is it has registered a record-breaking highest speed of {{cvt|129.2|km/h|mph}} even if it has an engine that uses only compressed air. This car was developed by the company's "Dream car workshop". This car is nicknamed as "sleek rocket", or "pencil shaped rocket".<ref>{{cite web|url=http://www.physorg.com/news/2011-09-toyota-three-wheeler-mph-compressed-air.html |title=Toyota three-wheeler does 80.3 mph on compressed air |publisher=Physorg.com |accessdate=2012-08-11}}</ref>

As part of the TV-show [[Planet Mechanics]], [[Jem Stansfield]] and [[Dick Strawbridge]] converted a regular scooter to a compressed air moped.<ref>{{Cite web|url=http://www.nationalgeographic.com.au/watch/program_details.aspx?id_program=2096|archiveurl=https://web.archive.org/web/20080401235339/http://www.nationalgeographic.com.au/watch/program_details.aspx?id_program=2096|url-status=dead|title=Compressed air moped conversion|archivedate=April 1, 2008|accessdate=May 29, 2020}}</ref> This has been done by equipping the scooter with a compressed-air engine and air tank.<ref>{{cite web |url=http://www.ecogeek.org/content/view/1549/69/ |title=Compressed air moped being built by Jem Stansfield |publisher=Ecogeek.org |accessdate=2010-10-13 |archive-url=https://web.archive.org/web/20100811091501/http://www.ecogeek.org/content/view/1549/69/ |archive-date=2010-08-11 |url-status=dead }}</ref>

In 2010, Honda presented the Honda Air concept car at the LA Auto Show.<ref>{{cite web|url=http://www.greenoptimistic.com/2010/10/22/honda-air-compressed-air-car/ |title=Honda Air concept car |publisher=Greenoptimistic.com |date=2010-10-22 |accessdate=2012-01-26}}</ref>

Since 2008 the former Bosch Rexroth, now Emerson is organizing the Emerson's International AVENTICS Pneumobile Competition in Eger, Hungary. It is a competition for students in the higher education to build racing vehicles propelled by compressed air.<ref>{{cite web|url=https://en.pneumobil.hu/news |title=Pneumobile2020 |publisher=pneumobil.hu |date=2020-03-09 |accessdate=2020-03-09}}</ref>
[[File:PowAir.jpg|thumb|Óbuda University PowAir Pneumobil Team]]
There is an international conference related to the event organized by Óbuda University, Department of Bánki Donát Mechanical and Safety Engineering.<ref>{{cite web|url=https://en.pneumobil.hu/conference/2020 |title=ACIPV2020 |publisher=pneumobil.hu |date=2020-03-09 |accessdate=2020-03-09}}</ref>

=== Trains, Trams, Boats and Planes ===
[[File:Tram Nantes AMTUIR.jpg|thumb|Preserved Nantes compressed-air tramcar at the AMTUIR museum]]
Compressed-air locomotives are a kind of [[fireless locomotive]] and have been used in mining<ref>{{Cite web|url=http://www.aqpl43.dsl.pipex.com/MUSEUM/TRANSPORT/comprair/comprair.htm|archive-url=https://web.archive.org/web/20160303202958/http://www.aqpl43.dsl.pipex.com/MUSEUM/TRANSPORT/comprair/comprair.htm|url-status=dead|archive-date=March 3, 2016|title=Compressed-Air Propulsion.|date=Mar 3, 2016|accessdate=May 29, 2020}}</ref> and tunnel boring.<ref>{{Cite web|url=http://magazineart.org/main.php/v/technical/scientificamerican/ScientificAmerican1916-11-25.jpg.html|archive-url=https://web.archive.org/web/20160625084645/http://magazineart.org/main.php/v/technical/scientificamerican/ScientificAmerican1916-11-25.jpg.html|url-status=dead|archive-date=June 25, 2016|title=Scientific American 1916-11-25|date=Jun 25, 2016|accessdate=May 29, 2020}}</ref>

Various compressed-air-powered trams were trialled, starting in 1876.  In [[Nantes]] and [[Paris]] [[Mekarski system]] trams ran in regular service for over 30 years.<ref>{{cite web|url=http://www.tramwayinfo.com/Defair.htm |title=Tramway Information |publisher=Tramwayinfo.com |accessdate=2010-10-13}}</ref> See also [[Nantes tramway#Compressed-air trams (1879–1917)]].

Currently, no water or air vehicles exist that make use of the compressed-air engine. Historically certain [[torpedo]]es were propelled by compressed-air engines.

== See also ==
{{div col|colwidth=30em}}
* [[Air engine]]
* [[Alternative fuel]]
* [[Alternative propulsion]]
* [[Charging station]]
* [[Compressed-air energy storage]]
* [[Compression ratio]]
* [[Global warming]]
* [[Liquid nitrogen vehicle]]
* [[Pistonless rotary engine]]
* [[Plug-in hybrid]]
* [[Pneumatics]]
{{div col end}}

== References ==
{{Reflist|2}}

== External links ==
*[https://onlinelibrary.wiley.com/doi/full/10.1002/est2.159 Experimental investigation of a compressed air vehicle prototype with phase change materials for heat recovery]
*[https://www.advancedsciencenews.com/compressed-air-cars-for-urban-transportation/ Compressed air cars for urban transportation Sep 7, 2020] 
*[https://www.semanticscholar.org/paper/Thermal-analysis-of-near-isothermal-compressed-gas-Odukomaiya-Abu-Heiba/bbee01060bb3c1f797bb944b01793ddd64065adc Thermal analysis of near-isothermal compressed gas energy storage system] 
{{Commons category|Compressed-air-powered vehicles}}
*{{HowStuffWorks|air-car|Air-Powered Cars}}
*[https://web.archive.org/web/20080227234242/http://www.sae.org/news/airhybrid.htm Study: "Air Hybrids" Yield Fuel Savings] ([[Society of Automotive Engineers]])
*[http://www.epa.gov/oms/technology/#hydraulic Hydraulic Hybrid Research] ([[United States Environmental Protection Agency]])
*[http://opensourceenergy.org/Technologies/CompressedAir/tabid/182/Default.aspx OSEN page about Compressed Air Technology] {{Webarchive|url=https://web.archive.org/web/20080204085100/http://www.opensourceenergy.org/Technologies/CompressedAir/tabid/182/Default.aspx |date=2008-02-04 }}
*[https://web.archive.org/web/20070929062618/http://www.aircaraccess.com/history.htm Compressed-air vehicles history]
*[http://www.didik.com/ev_hist.htm Photograph of the 1903 Liquid Air Company car]
*[http://www.regusciair.com/index.html Regusci Air, Armando Regusci's official web]
*[http://www.engineair.com.au/ Environmentally Friendly, Engine, Invention | Melbourne]
*[https://www.youtube.com/watch?v=NBeky4EuyBc Air Powered Vehicle designed and built by students at San Jose State University]
{{Alternative propulsion}}
{{Environmental technology}}

{{DEFAULTSORT:Compressed-Air Vehicle}}
[[Category:Compressed air power|*]]