Hydrogen has a high energy density and is clean - burning to leave only water vapour.

BBC: Hydrogen's energy promise improves

Instead of being stored in batteries, the electricity made by solar panels can be used to split water into oxygen and hydrogen molecules, the latter of which can be used as a fuel with high energy density.

WHITEHOUSE: Engage and Connect

Hyperpolarisation not only compensates for the low density of the gas (the 3He is 10, 000 times more polarised than the hydrogen in water), it also allows images to be taken rapidly enough to avoid any blurring due to a patient's natural tendency to breathe.

ECONOMIST: Medical imaging