I'm not an expert at any of this stuff and this math could very easily be wrong, but I just spent some time with Wolfram Alpha validating that claim. a 40,000 liter hydrogen truck can carry 425 gigajoules of liquid hydrogen; if it drives 500 miles, a diesel tractor trailer getting 5mpg would burn 100 gallons of diesel, that's 14 gigajoules of energy (now keep in mind that much hydrogen only weighs 3000kg - a typical load for a tractor trailer is 10000-20000kg) - if it was a fuel cell truck, it could be twice as efficient as an ICE so would only need 7 gigajoules. 7 gigajoules is 1.6% of the transported 425 gigajoules of energy. A state of the art HVDC transmission line loses 3.5% per 1000 km, so it seems like a hydrogen truck might actually be more efficient than wires.