As for the timescale, fusion certainly wouldn't be available in the short-term, but the problem of providing viable energysources is not going to get easier even if conservation, CO2 sequestration, fission and renewables are more widely used, and there are currently no other large-scale options beyond the 20-50-year timeframe.
But in the bigger picture, the petrol-from-air idea joins a legion of others that are trying to crack the far bigger problem of storing energy produced by renewable sources.
Otherwise we are simply solving one problem, less dependence on fossil fuels, while creating another, a technology that produces energy from renewable sources but is not disposable at the end of its lifecycle.