Author: Kate Fialko

Kate Fialko is a fellow in the 2018 Leaders in Environment and Finance (LEAF) program. Kate spent the summer of 2018 with Orange Water and Sewer Authority (OWASA), where she assisted with an investigation into possible productive use of biogas from the wastewater treatment process. She built a preliminary model to determine whether a town could economically convert its fleet to run on CNG.

Many of us know the wastewater treatment process generates water clean enough to put back into the environment, but it also produces biogas. Biogas is the mix of gases produced by anaerobic digestion (the breakdown of organic material in the absence of oxygen) and, since a primary component is methane, it can be used as an alternative fuel source. Utilities commonly use a portion of the biogas they generate to fuel the digestion process and then flare the remaining biogas to dispose of it. Rather than just emit this excess biogas, some utilities are investigating additional ways to productively use biogas in order to save fuel and increase resiliency by creating a new energy source. Options include using the biogas to fuel a combined heat and power system and injecting processed biogas into a natural gas pipeline.

Another option is converting biogas into compressed natural gas (CNG) for use in vehicles.  Typically a utility needs to have consistent CNG customers for this to be worthwhile financially, and converting a municipal fleet to run on CNG could provide the needed demand. However, municipalities must carefully consider any fleet conversion decision to ensure they are using tax payer dollars efficiently. Continue reading