> the conversion is inefficient. It takes a lot of power to extract H2 from H2O. How inefficient? That number matters. If it takes 500 kWh to make a tank that

> the conversion is inefficient. It takes a lot of power to extract H2 from H2O. How inefficient? That number matters. If it takes 500 kWh to make a tank that stores 100 kWh, you'd be a fool to use that energy directly, as that tank is going to store hundreds of times that much (at least) over its lifetime.