[dmv]

How would systems running on petrol be carbon-neutral? Granted, you reduce one form of carbon emissions by presuming a clean form of energy and petrol generation. Use of the petrol, however, should still result in carbon emissions. Have I missed something?

[jbert]

If you're making the hydrocarbons from CO2 and H2O, you're taking as much CO2 from the air as burning the hydrocarbons will liberate.

Obviously, you need to put in the energy too. But I think synthetic hydrocarbons are a great way to carry around useful energy. They're very energy-dense, should be cleaner than oil from the ground and the whole world is tooled up to use them.

However, they're not useful until we also have:

- loads of power

- an efficient way of turning that power + CO2 + H2O into hydrocarbons