Didn’t see mention of natural gas as a fuel. That would make sense.
The article seemed to imply the whole thing is fueled by the heat value of the poo.
The internet is a very weird place. Here’s an article on the heat value of sewage sludge. Apparently it is somewhat higher per unit of weight than most types of coal.
https://web.anl.gov/PCS/acsfuel/preprint%20archive/Files/36_4_NEW%20YORK_08-91_1653.pdf
However, that is for dewatered sludge. Getting the water out requires energy, and I suspect it requires more energy than is gained when the dewatered sludge is burned.
There ain’t no such thing as a free energy lunch.
Acck, misread the article.
Sludge has roughly half the heat value per pound of coal.