As I sit here in mid fall, snug in my down vest and resisting the urge to run the furnace, my mind turns to energy and I smile. I am proud to work for Giffels Webster, a firm that consults with municipal public works departments, and takes energy consumption and conservation seriously.
We recognize that sewer and water systems are energy intensive and can consume between 130 and 40 percent of an average municipality’s energy budget. Energy is generally the largest cost component of a sewer/water department’s total budget. As such, one can expect to find some low hanging fruit in the areas of energy savings and conservation. Picking some of these juicy cost savings is one-way Giffels Webster helps our municipal clients to improve the lives of their citizens and the overall environment in their community.
Here’s an example of such a project involving the Oakland County Water Resources Commissioner’s office and the Commerce Township wastewater treatment plant. Giffels Webster designed an innovative heat-recovery system that was installed at the Commerce WWT plant near the end of last year’s heating season. This system uses a heat pump to move heat from the clean, treated water flowing out of the plant, to an air unit that provides heat to the building. It works similarly to geothermal energy by capturing heat from treated wastewater, which has a constant surface temperature of approximately 55 degrees.
Think of the relatively warm water that flows out of these treatment plants as an energy source, which can be used to heat the buildings in the treatment plant. The system is cost-effective, reliable, sustainable and environmentally friendly, and requires no wells. In a typical winter the Commerce heat-recovery system will save approximately $50,000 in natural gas heating costs. We call this a very attractive piece of low hanging fruit, providing a return on investment in roughly five years. It also has an immediate benefit: Commerce Township will pass this reduced operational cost on to the customers of its system.
We believe that while this is the only system of its kind in Michigan, there are many treatment plants in our state and around the world where this process could be replicated. It could also be used as a heat source for the neighborhoods and local businesses surrounding the treatment plant. In this example, Commerce Township is only using a fraction of the available energy generated by the heat-recovery system. There is additional energy that might be used to heat the industrial facilities across the street, or the residential neighborhoods around the plant. This energy source could also be used to cool buildings during hot summer months.
Could we eventually create a municipal utility that sells this energy? Why not? The technology for this type of system is already well advanced. It is used in air conditioners and geothermal heat pumps. However, the specific costs and benefits associated with creating a municipal utility of this type are yet to be analyzed.
Might there be another low-hanging fruit opportunity that is underfoot? Maybe, maybe not. Heat recovery is certainly a source of energy that we could incorporate into the country’s energy portfolio. And anything that helps fill that basket is a piece of fruit worthy of consideration.
1http://water.epa.gov/infrastructure/sustain/energyefficiency.cfm