Or is 1080 watt-hours rather underwhelming for a fuel cell system that weighs 18 Kg? That's only 60 watt-hours per kilo, which is within the reach of standard nickle-metal-hydride batteries, never mind lithium-ion. And that's just rechargeable batteries. There are a range of lithium chemistry primary batteries already used by the military that can achieve energy densities four or five times higher than this.

I'm not sure, but I think the article states that that's the weight of 3 cartridges, each of which holds 1080 watt-hours.

i think the idea is to eliminate recharging time, rather than energy density, you could essentially completely refill the fuel cells in minutes without interrupting the power flow, although chemical batteries may allow for this too, but offend the greenies.

a couple cartridges might be enough to drive a fuel cell motorcycle reasonably well