On the heels of the failed Puegot 208, any other hybrid air cars in development?

[Galvatron1]

https://www.caranddriver.com/news/a1...id-technology/

Or is a compressed air hybrid not possible at this time? Some articles had stated 141 mpg, I believe, had it made it into production. But since it’s a subcompact, it probably would never make it to America. Still, a novel approach to decrease gas consumption, without the cons of battery electric hybrids.

[freebeard]

Lacks infrastructure. You have to remove heat compressing the air and then heat the decompressed air. I remember discussing a research effort to resolve that a year or two ago.

I could use the site's Search function, but you're the one that cares.

[oil pan 4]

The problem with compressed air is about half the energy is lost to heat compressing the air. That's why batteries rule.

[Isaac Zachary]

I've always thought of liquid air (or liquid nitrogen) and compressed air vehicles as having cold as a byproduct, which can be used for something like an air-conditioner. This is the opposite of ICEV's that have heat as a byproduct.

EV's don't produce much heat and no cold. So they need to pump heat in or out of the cabin if you want to be comfortable in hot or cold weather.

[freebeard]

I had an extra tab open so I tried the Search function. Fruitlessly. There was some University research gone commercial about extracting and storing the heat and using it to warm the decompressed air.

But I did find this article via DDG:

solar.lowtechmagazine.com: History and Future of the Compressed Air Economy:Historical compressed air systems hold the key to the design of a low-tech, low-cost, robust, sustainable and relatively energy efficient energy storage medium.

First Lesson: Avoid Energy Conversions

I've always thought wind powered compressed air is very elegant. The compressed air network in Paris spanned 25 kilometers.

Second Lesson: Use Heat and Cold for Other Purposes

Today, most CAES engineers are focused on further improving efficiency by using the waste heat of compression to reheat the compressed air upon expansion. This method is called “Advanced Adiabatic CAES” (AA-CAES) or “fuelless CAES” and removes the need to reheat with natural gas as in the standard “diabatic” CAES. The technology is expected to reach an overall efficiency of roughly 70%, bringing it closer to the efficiency of chemical batteries and pumped hydropower storage plants. 7

This is what the research I'd seen was about. But there's a necessary link between where the air is compressed and expended. Not so hot for moving vehicles.

Third Lesson: Improve the Air Compressor

This part I thought was cool. I've seen homemade trompes on Youtube made from 2-liter bottles:

Once again, it pays to look to the past for inspiration. Surprisingly, the holy grail of “isothermal” air compression – in which no waste heat is produced at all – was found at least 400 years ago. The hydraulic air compressor – or “trompe”, as it was originally known – was an Italian invention first mentioned by name in 1588, but possibly already known in Antiquity.

From the 1600s onwards, dozens of “trompes” furnished a continuous air blast to early iron and brass-smelting furnaces in the French/Spanish Pyrenees. 2628 Compared to a waterwheel running a wooden piston compressor, it was roughly three times more efficient, allowing higher iron production with less water power resources.

Over a 33-year period starting in 1896, eighteen gigantic hydraulic air compressors were built, mostly in the US, Canada, Germany and Sweden. In the largest of these installations, which were partly or completely built underground, water and air fell through pipes and shafts – hewn out of the rocks – which could be more than 100 metres deep and up to 4 metres wide. The delivery pressure amounted to 8 bar and the power output could reach 3,000 kilowatts.

That's 3 Megawatts from falling water!

[freebeard]

Maybe it's worth mentioning that I keep pointing to the Scuderi Split-Cycle engine.

Scuderi Split-Cycle Engine

That was 2008. IMHO his heirs squandered his intellectual property. Same way as Elio, they tried to develop their own proprietary inline four.

But one could generate compressed air on regenerative braking and recharge at home from that babbling brook.

[redpoint5]

Battery hybrid solves other problems too, like keeping the AC running while the engine is off. By electrifying everything, all systems can operate regardless of the ICE running. Compressed air would need a similar way to run accessories.

[Isaac Zachary]

Originally Posted by redpoint5

Battery hybrid solves other problems too, like keeping the AC running while the engine is off. By electrifying everything, all systems can operate regardless of the ICE running. Compressed air would need a similar way to run accessories.

There are non-hybrid vehicles with start-stop systems. Of course those still have the option to idle the engine of need be. But maybe an air motor vehicle could work in a similar way.

Or use a second small air motor for the accessories.

[jakobnev]

If the tank is filled at home maybe the heat from compression can be used to heat your house or water.

And when operating in hybrid mode heat from the ICE could be put back into the air in multiple stages.

[Autobahnschleicher]

Originally Posted by Galvatron1

Or is a compressed air hybrid not possible at this time?

Compressed air is a terrible medium for storing energy.
You lose a lot of energy to heat when compressing air and require heat to expand it somewhat efficiently.
That's why cordless tools and hybrid cars are running on lithium ion cells, not compressed air tanks.

Only advantage of storing energy in compressed air is that pneumatic cylinders can be used for suspension and active aero