That's an interesting question.
Today, electronic vehicles struggle to get to around the 100-kilometre range. What we've seen as we do work on batteries is that with lithium-ion technology, nickel metal hydride, lead acid, and so on—but nickel metal hydride is the premium one right now—as you add energy into a battery, because to get more range you need to have more energy in a given space, you challenge the safety aspect of the battery. Today we're at 140 or 150 watt-hours per kilogram, and to get to 500 kilometres you'd have to be at roughly 750 watt-hours per kilogram to have the same size of battery in a vehicle, which is already quite large. For all known battery—