The only reason for large gasoline motors in cars is for acceleration. maintaining speed even at highway speeds can be accomplished with a very small light gas engine. Gas electric Hybrids take advatage of this but batteries are still a problem. They are heavy, they wear out, they are expensive and they pose an environmental risk. I propose a gas/pneumatic car. The gas engine and regenerative braking would actually provide all the needed power, unless you wanted to charge the air tank beforehand for slightly better gas mileage the first couple of miles. Light weight air tank/s would replace batteries. and air motors would replace the electric motors. The tank would be charged while brakig and be slowly charged up by the gas engine when the gas engine's full power is not needeed. The air motor would provide short quick burts of power for leaving a stoplight, on ramps or an extra push up a hill. similar cost to gas/electric, no batteries ot wear out, or pollute.
-- tedhaubrich, Jun 08 2004

Oxygen generator http://www.appliedo...ygen_generator.html
[kbecker, Oct 17 2004, last modified Oct 21 2004]

pre-compressed-air supercharger http://www.halfbake...-air_20supercharger
[Globi]'s link as a link. [phoenix, Oct 17 2004]

Air-Powered Cars Roll Into Production http://www.howstuff...om/news-item106.htm
[tedhaubrich] link as a link. [phoenix, Oct 17 2004, last modified Oct 21 2004]

turbo pneumatic hybrid turbopneumatic_20hybrid
Similar hybrid using a gas turbine instead of a regular engine [atomico, May 26 2008]

Ignition Exhaust only Internal Combustion Engine Ignition_20Exhaust_...Combustion_20Engine
Two stroke combustion cycle using compressed air [caspian, Sep 27 2013]

Miller Motor Jet Miller_20Motor_20Jet
Incorporates an engine that puts out compressed air as part of its cycle [caspian, Sep 27 2013]

Yes this idea is similar to the gas/hydraulic ideas and gas/spring ideas. Problem with springs is just the sheer size of a spring needed, but might still work, I don't know much about hydraulics but all applications I'm awar of involve huge amounts of torque at very low speeds.
-- tedhaubrich, Jun 08 2004


If the excess power of the engine would be used to run a refrigerator it could liquify some air and distill off the Oxygen (similar to devices in link). To get top power the Oxygen instead of plain air could be used to boost combustion. That way you don't need huge tanks. Intermittent energy from braking could also help to run the compressor instead of being wasted into heat.
-- kbecker, Jun 08 2004


I think this is the same concept: http://www.halfbakery.com/idea/pre-compressed-air_20supercharger#1016072382

I favor the idea especially in combination with a Diesel. (Simpler implementation than an electric hybrid)
-- Globi, Jun 08 2004


http://www.howstuffworks.com/news-item106.htm I guess this idea is baked in regards to pneumatic electric, The advantage of that I don't really understand. I hadn't thought about feeding compressed air into the engine Globi, I was thinking about a sepeate pneumatic motor but perhaps feeding it into the gas engine would get a better payoff. Though baked in slightly different forms, super/turbo/nitrous oxide systems.
-- tedhaubrich, Jun 08 2004


An engine can be run as a pneumatic motor as well as a compressor. Some engines (especially large engines) actually use pressurized air to start them. So you don't even have to combust the air that you feed the engine with.

A Diesel has a much higher compression ratio and no throttle. So it would be much more effective in pressurizing air, when braking. In addition a Diesel can basically be run with any air fuel ratio, which would add a lot of flexibility.

By the way, the most fuel efficient commercially available car is not even a hybrid. It's a diesel powered car (Volkswagen). So this might actually be a simple solution to even further improve this cars efficiency.

Oh, and if the engine was connected to a fast CVT gearbox it could even control the speed of the engine, depending on how much you brake (instead of the gearbox controling the speed of the wheels, which in this setting would act as a compressor).
-- Globi, Jun 08 2004


If the compressed air is produced and used in the engine instead of a separate air motor, there are a bunch of other ideas on the half bakery that this would go well with:

You could have the air compression for storage happening as part of the four-stroke cycle.

Globi already mentioned the pre-compressed air supercharger idea.

You could use the compressed air instead of compressing it in the engine leaving more engine power available for high power demand (heating it first or not, as desired)

You could use the compressed air instead of compressing it in the engine, so you can skip the compression stroke and run a two-stroke cycle.
-- caspian, Sep 27 2013



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