It's intended to be built-in to the nosewheel assembly but the prototype/demonstrator is not. It came to my attention because of the technology involved and because the company behind it is trying to raise investment to develop it.
My question on this forum is directed towards its practical use: for example, if you can eliminate the fuel usage during taxi this is arguably a Good Thing (it's the sort of hybrid petrol/electric car thing, like the Toyota Prius) eliminating fuel wastage and pollution. But I don't know enough about modern turbofan warm-up to know whether a very late engine start prior to take-off is desirable.