Kuala Lampur, June 5 -- Green hydrogen has become the darling of the net-zero world. Politicians love announcing "gigafactories." Energy executives call it the "Swiss Army knife" of decarbonisation. But if you strip away the glossy PowerPoint slides and the subsidy promises, you're left with a brutal engineering reality: we are not yet very good at making the stuff affordably or efficiently. That is precisely why a recent review is so refreshingly necessary. It is not another cheerleading session for a hydrogen economy. Instead, it reads like a sober field manual - one that quietly confirms what many insiders fear but few say aloud: the road to green hydrogen is paved with good intentions, thermodynamic limits, and very expensive membrane...