 The study examined the potential role of hydrogen in the energy transition, taking into account the temporal variability in the system as well as the dynamics of learning effects. It found that a faster scale-up of electrolysis and renewables than envisioned by the EU in the Aipau EU plan can be cost-optimal to achieve the most stringent climate target plus 1.5 degrees Celsius. This would reduce the cost of hydrogen production to €1.26 per kilogram by 2050. The study also showed that if electrolysis costs were modelled without dynamic learning by doing, the electrolysis scale-up was significantly delayed, while total system costs were overestimated by up to 13%, and the levelised cost of hydrogen was overestimated by 67%. This article was authored by Elizabeth Zayin, Marta Victoria, and Tom Brown.