Hydrogen is poised
to play a key role in the energy transition
by decarbonizing hard-to-electrify sectors and enabling the storage,
transport, and trade of renewable energy. Recent forecasts project
a thousand-fold expansion of global water electrolysis capacity as
early as 2030. In this context, several electrolysis technologies
are likely to coexist in the market, each catering to different applications
and geographies. They face the common challenge of decreasing the
cost of hydrogen produced, for which energy efficiency is a major
but not the only factor. In this Perspective, we dispel common misconceptionsrooted
in outdated designsaround alkaline water electrolysis and
offer an overview of the main technical pathways to reduce the cost
of hydrogen from modern systems already under commercialization. By
identifying key research needs, we aim to motivate work into overlooked
areas that both offer interesting scientific questions and can contribute
to the gigawatt-scale production of green hydrogen in the short- to
medium-term.