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Yea I've read that article a long time ago.
I've done some calculations before on how much power you can get out of this. You know how the Prius has a longer expansion stroke? The Prius doesn't even see 10% higher peak efficiency than its non-Atkinson cycle engines. That's an ideal scenario for the waste exhaust pressure, to be able to expand it adiabatically with a piston. The moment you blow it out of an exhaust valve, you lose some of the energy, and having it go through a turbine makes you lose half of the energy too.
The key thing to note is that an engine doesn't consistently flow gas; Exhaust gases come out of the cylinder first in a "pulse" as the residual cylinder pressure blows the gas out, and then the rest of it is pushed out by the piston. Only the "pulse" is useful for producing work, the rest of the gas flow uses the piston's energy. Exhaust energy can be thought of having 2 components in some sense, the component that is "free", aka wasted energy that the piston did not absorb, and the component that comes from the piston pushing against the exhaust gas. A turbocharger uses both.
Turbocharging is very inefficient, but it is simple (practically "bolt on"), effective (we all know how much power turbo engines can make), and more efficient at full load than a supercharger. A supercharger uses 100% shaft power to create boost, while a turbocharger can utilize some of that "pulse" energy. The reason it is inefficient is because it is designed to produce as much boost as possible, not increase efficiency. To produce boost, the turbocharger dams up pressure in the exhaust, which requires engine shaft power to maintain. However when the exhaust valves are opening before the piston bottoms out, that extra "pulse" makes it to the turbocharger and imparts some extra work. A well designed turbocharger has more boost pressure than exhaust backpressure, which means it is utilizing those "pulses".
Another reason to turbocharge is that despite being less efficient, downsizing the motor improves part load efficiency simply because you have to use more of the available power and because the smaller engine has less losses.
I'm not saying that this is a bad idea or that it doesn't work, just that under most driving circumstances it does not represent a big efficiency increase over a belt-driven alternator. For peak power, it can generate an appreciable amount of extra energy, as they are doing with F1. You don't need to be an engineer to see that energy doesn't come from nowhere.
You did read my previous posts right? I explained it pretty well IMO...
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