If The Graduate’s family friend were giving automotive investment advice today, instead of “plastics,” he might well suggest “hydraulics.” While gasoline/electric hybrid cars are still ascendant, hydraulic hybrids could well be the new frontier.
Consider: Earlier this year, PSA Peugeot Citroen and Bosch announced the joint development of a hydraulic hybrid powertrain for passenger cars with a claimed 45% fuel savings in urban driving. NRG Dynamix, a Michigan start-up, is currently soliciting automakers to consider its “Drop ‘N Hybrid®” hydraulic transmission, with a claimed 60% fuel savings shown in an experimental compact pickup truck. And Eaton, a major supplier to the automotive industry, is already offering its HLA® hydraulic launch assist system on commercial refuse trucks.
A Long Time Coming
Eleven years ago, Ford showed off its Mighty F-350 Tonka concept pickup at the Detroit Auto Show. Look beyond the toy-truck motif and you’d see the debut of Eaton’s hydraulic launch assist. At the time, Ford said HLA could reduce fuel consumption by 25 – 35% in stop-and-go driving. Then-Group VP Richard Parry-Jones noted, “We believe this technology holds promise for making large trucks more fuel efficient and environmentally sound.” Although Ford did not go further with this technology, Eaton did.
But the most interesting automotive development is from Europe, where PSA Peugeot Citroen – a company not familiar to most Americans – is getting ready to launch a Prius-fighter. Keep in mind that in Europe, diesels are the popular choice for fuel efficiency. But more stringent emissions standards are forcing European automakers to consider alternatives. More and more of them are now offering some type of hybrid vehicle – like the Peugeot 3008 Hybrid 4 diesel/electric – but just as in the U.S., the Toyota Prius is king. And that doesn’t make the Europeans very happy.
Enter the hydraulic hybrid, an amazingly simple idea that switches out all the electric motors and batteries of a “typical” hybrid with a hydraulic pump/motor and a compressed air tank.
How It Works
Take a Prius Hybrid Synergy Drive system’s motor/generators and replace them with hydraulic pumps and motors, then for energy storage, switch out the battery pack and replace it with a compressed air tank. That’s the PSA Hybrid Air system in a nutshell. And in fact, Hybrid Air operates with the same types of driving modes.
A gasoline engine drives the front wheels and it turns a pump that runs the hydraulic system. The power of hydraulics is used to compress air – actually pure nitrogen – in a storage tank. At low speeds, the gasoline engine can shut down completely, and the compressed air can power the hydraulic motor, which will drive the front wheels. In Air Power mode, it’s a zero-emissions vehicle.
Higher speeds and cruising bring the gasoline engine back on line, and the hydraulic/air system plus gasoline engine can combine for maximum power. Hybrid Air even has regenerative braking, with the front wheels then powering the hydraulic pump to “charge” the air tank.
PSA claims that in city driving, a Hybrid Air vehicle can run on compressed air alone up to 80% of the time. In the admittedly liberal European combined cycle, a Ford Fiesta-sized Hybrid Air car could get 81 mpg.
Advantages vs. Electric Hybrids
- According to PSA development chief Guillaume Faury, the system only adds about 220-lb. of weight – much less than the motors and batteries of an electric hybrid
- It’s less costly to produce and, according to PSA, will be available in vehicles priced less than 20,000 euros (about $26k).
- All the materials involved are plentiful and easily recyclable – unlike batteries with their rare earth elements.
- All of the components use known, existing technologies, for easier and less costly vehicle maintenance.
- It’s a technology that can be adapted to all global markets and climates, with no adverse effects on range or driving dynamics.
Three Years From Now
PSA has filed 80 patents for this system, and is working toward a production target of 2016. Hybrid Air will likely appear in a vehicle based on the Peugeot 208, using a 3-cylinder gasoline engine along with the hydraulics and compressed air.
Of course, Americans won’t be able to go down to their local Peugeot or Citroen dealer and check it out. But if this technology is as promising as it seems, we are sure to see some application in the U.S.
Beyond that, it shows that alternatives to our current “alternate technology” are still out there, ready to be explored.