Suppose we don’t get enough energy out of coil and onion for break-even, the thermal system needs to get to its operating temperature. That means, we’ll need the energy of maybe a few thousand shots of the DPF. So a petrol engine in combination with a conventional generator (or similar) needs to provide enough electricity continuously to recharge the capacitors enough before the system runs at its desired frequency. The first shots may take place every ten seconds or so, getting gradually faster.
Pretty much what James writes, but with respect the thermal system is needed to come into gear before the FF device can support itself.
