Hydrogen is energy dense and emission-free in use, which make it a valuable energy carrier in a zero-emission future. Hydrogen can replace fossil energy in many cases where batteries have important disadvantages, e.g. long-distance transport. The demand for hydrogen is expected to multiply in few years as fossil fuels are increasingly phased out. Hydrogen investments may be necessary for the low-emission society, but there is also a risk of it being a dead end. A failed investment in climate technology will waste critically important time and resources. To avoid this, it is crucial to understand where the opportunities and risks lie.