I read about this a few weeks ago. Like many manufacturers, Peugeot inside the PSA Group has a “skunk” works looking at different types of engines and propulsion systems. One of their ideas was to take a concept widely used in commercial vehicles and add it to their passenger vehicles to improve fuel consumption – the age old desire to extract more out of every gallon or litre of fuel.
Peugeot renamed their idea “Hybrid Air” because it used compressed gas to help reduce the load on the petrol driven motor. It certainly is a hybrid and it uses “air” of sorts for a type of propulsion though the name makes it sound like the engine ran on a mix of airs (if that is a word)! This isn’t the fabled compressed air motor that has done the rounds for decades.
After several years PSA is slowing down the development due to the huge costs involved and the lack of partners getting involved. This is despite other manufacturers looking at similar concepts and commercial truck manufacturers not wanting to share an evolution. In addition, the price of oil has dropped substantially thus making current models and fuel economies very marketable.
What is Hybrid Air?
This is actually a hybrid petrol hydraulic motor unit. It has a petrol driven internal combustion engine and uses brake regeneration and deceleration to power a compressor that squashes air into a tank very quickly. Then when the car accelerates from a standing start, the compressed air helps drive the wheels, reducing the work effort required by the petrol motor. This in turn reduces the fuel needed by the main engine and means a lighter and smaller capacity motor can be used. A great idea for town driving where higher speeds are not necessary.
Peugeot fitted an experimental unit into a 208 and a 2008 model to test it and their sister company Citroen fitted one to a C4 Cactus. A 1.2 litre 3 cylinder motor was used with a hydraulic pump and motor used to send the compressed air back to power the drive. A new gearbox was designed to cater with the different power units using a concept called epicyclic gears.
Peugeot developed a three mode propulsion system – so many cars and bikes now have different modes for usage these days! The first was a compressed air mode for town driving, however it still needed the petrol motor to kick in to help the compression at times. Mode 2 is purely petrol powered for highway usage and Mode 3 is a combination for more power.
In order to make this work, the whole car has to be lightened which again meant spending money figuring out how to reduce weight whilst retaining strength and crash survivability. Peugeot used carbon materials, thinner steel and other easily manufactured components to reduce the weight of the car – bearing mind that the hybrid unit is more complex than a standard motor, which in turn would increase the weight. The 208 based concept had work applied to smooth out the body, reducing drag, even to the point of working on the shape of the mirrors and the glass surroundings.
The petrol engine was also tweaked to reduce friction – a major source of power loss – by using a new coating to slightly reduce this loss. Finally low resistance tyres were added as well.
The Costs and Payback
Clearly taking an idea from the commercial vehicle world and shrinking it to suit a passenger car was going to cost a bucket of money. Components are heavy on a truck or bus but need to be much lighter whilst retaining strength. This means using newer, potentially more expensive materials to achieve the result. Surprisingly, no other manufacturer wanted to get involved – presumably due to timing. As described above, the initial work started when the price of oil was rapidly rising and then suddenly it dropped and settled at a price 30% of the peak, thus making this project borderline profitable.
A spokesman for the company suggested that 500,000 cars would need to be built and sold per year to make it worth-while – or a significant rise in oil prices to frighten fleet operators! The company clearly looked at the market and decided that they wouldn’t be able to sell that many per year and make money on each one. Perhaps after being dormant for a couple of years, we’ll see this and other concepts bounce back.
I could see a future where a lot of these ideas are brought together into a smaller sustainable unit using under 1 litre motorcycle engines to power the rear wheels and a hybrid motor powering the front. The shells would be made of a material that doesn’t continue to use oil and would be strong but lightweight – possibly using recycled materials extracted from the vast dump sites around the world.
I think the KERS and other regenerative braking systems will take off and be widely used as well as new solar panels fitted to the upper skins. Batteries will get smaller, cooler and more fuel outlets will cater to a wider mix of fuels including a standardised “Swap & Go” battery system. Car parks will have row upon row of charging stations too. We will move away from “range anxiety” as entrepreneurs grasp the opportunities to supply the power outlets – we’ll see a new style Rockefeller family appear!