Wastewater operators have spent many hours telling the public how their plants make two great products: Clean water and valuable fertilizer/soil conditioner.
Now there's a third: clean energy. Of course, making electricity and heat from digester methane (biogas) is not at all new. But these days the bar is being raised. It's no longer enough for plants to conserve energy and make some for themselves. Now the goal is to make plants energy self-sufficient or, better still, net producers of energy.
Indeed, that filthy water flowing into the headworks looks more like fuel every day.
Think of
