How great is the potential for digester methane as an energy source?
Curtis: Speaking for New England specifically, there has been a trend to abandon sludge digestion. In my opinion, that is going to be reversed. For a time it was seen as expedient to eliminate digestion in favor of less costly alternatives. In Connecticut, for example, there are five commercial sludge incinerators. That has been the fate of the vast majority of sludge — it’s burned. Of late, with concern about energy conservation and climate change, the value of that carbon resource is becoming apparent, and new digestion opportunities are arising. Several larger plants have built digesters in the last few years in New England, and more are on the drawing board. Of course, getting back into digestion has financial implications. It’s a multimillion-dollar decision for a midsize facility. Also on the supply side, there is an occasional plant adding internal hydropower generation — typically pretty small, but it has some advantages. There’s also a significant effort in bringing high-stren
