Hydrogen as an energy carrier: constraints and opportunities

The use of molecular hydrogen (H2) in the energy sector faces several technical and economic hurdles related to its chemical and physical properties, particularly volumetric energy density and mass. The production, transport and storage of hydrogen, both in gas and liquid form, are intrinsically inefficient and expensive. Moreover, the mass production of green hydrogen would preferably use surpluses of renewable electricity that will be largely available not before the next decade. To fulfill the great potential of H2 in the decarbonization of the global economy - which should greatly accelerate - applications must be carefully selected, favoring for instance hard-to-abate sectors with respect to low-temperature residential heating or long-distance transportation versus light duty vehicles. In the meantime, research on production, transportation and storage of H2 must substantially leap forward.