Wow, really impressive. Hopefully there's no downsides because that's quite the renewable energy source! Even if its relatively minor, if its even 1% of a metropolis's power then why not go for it if its also treating the sewage at the same time!
Today, we are way more ahead than we are at once in 2005. I read, few month ago, an article on bionic leaf that breaks down the photosynthesis process to produce fuel and chemical. It also uses soil bacteria for the same.
This is not new. Orianna bretschger has process scale microbial fuel cells cleaning sewage and generating power, in operation for example at whitelabs brewers yeast repository in California
Could you use the gasses released by fermentation to power turbines, or would the amount of power generated not be worth it?