PSA Hybrid Air – because energy storage doesn’t have to be a battery

hybrid-air-1Not exactly breaking news: PSA’s Hybrid Air tech has been in the press for a while, but they showed the Cactus concept at Frankfurt and are saying that the technology will be available in production cars from 2016.

Citroen seem to have a historical obsession with hydraulic air technology, and often bizarre yet ingenious innovation, from the legendary and huge selling DS to the present day. Their hydraulic air suspension is notable, and now alongside Bosch they are applying air and oil pressure technology to drive/energy storage.

It makes a lot of sense though: the technology is (in principle at least) mechanically simple, doesn’t require a great deal of exotic materials or rare earths, and it’s light with an estimated weight saving of up to 100 kg compared to a battery Hybrid, which is the first step towards efficiency. Also: the storage system should lasts a lot longer than batteries, without the gradual loss of capacity after multiple charge cycles, and fewer recycling issues. The system is effectively simpler, lighter and cheaper than a battery, using tested technologies

The PSA Bosch hybrid system uses pressure from the engine and also from regenerative braking – using compressed air to improve the efficiency of the combustion energy, just as an electric Hybrid does.

But this is by no means the first application of air pressure in vehicle drive – Cyril Negre is a notable pioneer of air powered vehicles, and a collaboration with Tata to actually build one seems to have re-surfaced, having gone quiet for a year or two. Plus air pressure has been used in heavy goods vehicles for some time.

Chrysler also built a Minivan Hybrid using the a pressurized Hydro drive back in 2010/11 – more information here.

And if you look around online there are even companies offering to convert a regular car to the technology.
Some further reading on air vehicles:

More about the PSA Bosch Hybrid technology…

To cope with the challenge of creating an environment-friendly vehicle, PSA Peugeot Citroën is developing an all-new technology combining Gasoline internal combustion engine and compressed air storage. “Hybrid Air” is a key step in the path toward fuel consumption of 2 l/100 km. The major innovation lies in the way the powertrain adapts to driving styles, adjusting independently to one of three modes: Air, Gasoline, Combined. Hybrid Air technology will be fitted on B-segment models starting in 2016.

PSA Peugeot Citroen’s Hybrid Air incorporates a petrol engine, a unit to store energy in the form of compressed air, a hydraulic motor-pump assembly and an automatic transmission working with an epicyclic gear train.

Energy storage is via a longitudinally mounted central pressure tank, with a lower pressure hydraulic storage tank at the rear to provide pressurised fluid to drive to the front wheels via hydraulic motors.

The vehicle can be driven conventionally via the combustion engine, or by air/hydraulics alone, or a combination of both for maximum power applications: as with typical battery/combustion EVs.

Kinetic energy generated when decelerating/braking is converted into hydraulic energy and stored in the accumulator for vehicle propulsion as required, including when moving away from rest and for relatively brief periods in town. And the combustion engine can also charge the air system.

The technology remains fairly closely guarded, with at least 80 patents filed by PSA Peugeot Citroën, and little technical data available at this time, but it appears though the drive is via the front wheels, regardless of the source, with the hydraulic system positioned between the combustion engine and the automatic gearbox.

PSA plans to use the system in small/compact cars, but they have hinted that it could have a role for light, urban delivery vehicles.

Claimed figures/data:

  • 69g CO2/km homologated performance, i.e. 2.9 l/100 km (internal combustion, manual gearbox, benchmark of 104g CO2/km) for a conventional body style, such as the Citroën C3 or Peugeot 208, without any specific adaptations
  • Savings of 45% in city driving, offering a 90% increase in range in comparison with conventional engines
  • 60% to 80% in ZEV mode in city driving, depending on the traffic
  • Vehicle space maintained (boot, cabin, modular design)
  • Reliable and robust: an essentially mechanical system, for easier and more economical maintenance
  • Small environmental footprint. Easily recyclable materials
  • Affordable
  • Global. Can be industrialised on numerous markets

See more on the PSA website here:

Press coverage from Frankfurt of the Cactus concept:

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