Pretty clever to use the engines to generate power at scale - as a plus, if there are any efficiency gains (whether in power production or pollution terms) they may make their way back to the aerospace industry eventually. Complaining about carbon monoxide production and formaldehyde in these things suggests to me that the cons aren’t as serious as the article suggests, as carbon monoxide is produced by every combustion engine on the planet and formaldehyde remains used in a great number of things. If that’s the worst outputs from these engines then I’m sure there are many far more harmful methods of generating power.