4 ms·

Photosynthesis produces oxygen from water. Burning hydrogen creates water. So, plants are the answer.

• adhesive_wombat 3y ago
  Exactly, as long as there's CO2 to use (the inputs to photosynthesis are 6H2O + 6CO2). With atmospheric CO2 now over double the pre-industrial concentrations, there's plenty of that! And water would only be more available, by a tiny fraction, with lots of hydrogen burning. Oxygen is highly reactive so there's a replenishment mechanism at play to maintain the 21% we know and love in the atmosphere. Of course, if the phytoplankton give up the ghost that will end poorly for anything that likes to respire, but that's a completely different problem and would be as much of an existential issue with or without "white hydrogen" energy. In terms of scale, you'd have to burn around 1 trillion tonnes of hydrogen to bind 1% of the atmospheric oxygen into water (i.e. reducing the concentration from 21% to 20.79%: the same effect in terms of oxygen partial pressure as being 85m above sea level). This releases 40 billion GWh of energy, or as much energy as humans use, from all sources combined, in 225 years at present rates.