Color me skeptical, at least as the car is described in this poorly-written article.
There is no way a gas/air hybrid can run on air 80% of the time in city driving with air compressed by slowing down and braking. By definition, the energy produced this way must be less than 50% of the total used by the car during its trip, and when you figure in the losses in the various stages of the process a great deal less. I’d be very surprised if it’s as much as 25% of the time.
To get to the 80% number even for short trips you’d have to charge the air tanks initially, similar to recharging batteries in the garage overnight. Doing so, of course, uses electricity which must be generated using coal, gas or some other method.
Also, compressing air and then using it to drive motors, while highly convenient, is wildly inefficient.
The process for an IC car is: fuel burns, drives wheels, car moves.
For an air car it’s something like: fuel burns, drives turbine which turns generator to produce electricity, juice transmitted (with losses) to garage, electricity runs motor to run air pump, which compresses air with BIG energy losses, air is stored till released to run a not particularly efficient air motor which turns wheels, car moves.
Two stage process versus minimum five-stage process. By definition energy is lost at each stage, some more than others.
Okay. Looked it up and I’m not entirely right.
http://iopscience.iop.org/1748-9326/4/4/044011/fulltext/#erl323265s6.2
It is apparently possible to run such a hybrid with the fuel engine always operating at peak efficiency to either drive the vehicle or compress the air, then have it shut off when tanks are fully pressurized. A fuel engine operating always in its peak efficiency range is going to be much more efficient overall, so you are capturing energy efficiencies other than those associated with braking and slowing down.
I still suspect that by the time you run a complete analysis of energy used to travel 1000 miles it’s going to be tough to beat an efficient IC car by much, particularly the highly efficient diesels common in Europe but for unknown reasons not imported to here.
As anybody who has ever worked with compressed air knows, this process creates a LOT of waste heat. If they have found a way to use some of this heat it will help efficiencies considerably. The process also condenses a LOT of water out of the compressed air, which especially in humid climates will create some interesting challenges for the engineers.