Correction to: Nature Reviews Earth & Environment https://doi.org/10.1038/s43017-022-00333-5, published online 5 August 2022.

In the version of the article initially published, there was a typographical error in the third sentence of the second paragraph, now reading “Potential H2 energy generation for an average industrial wastewater site was on the order of 1012 KWh yr-1,” where 1012 appeared originally as “1,012.” The error has been corrected in the HTML and PDF versions of the article.