A kilogramme of hydrogen - the unit most often used – has an energy value of about 33.3 kWh.[1] So a tonne of hydrogen delivers about 33 MWh and a million tonnes about 33 terawatt hours (TWh). To provide a sense of scale, the UK uses about 300 TWh of electricity a year. 

It takes a good while to build out the physical infrastructure to deliver green hydrogen equivilants:

    Green hydrogen is made from renewable energy, producing zero pollution – its only by-product is steam. FFI’s ambition is to grow its green hydrogen production to 15 million tonnes of green hydrogen per year by 2030, accelerating to 50 million tonnes per year in the next decade thereafter.

The person doing this isn't in the "pinky promise" game, they built out a penny stock company from 2c a share to ~$28 a share over two decades to capture a large chunk of a billion tonne per annum raw iron ore market.