Repurposing Cathodic Protection Systems as Reliable, in-situ, Ambient Batteries for Sensor Networks

The majority of infrastructure is susceptible to, and therefore must constantly combat, corrosion. The monitoring and maintenance of corrosion protection (or the consequences of its unchecked failure) is often one of the leading costs of infrastructure upkeep. Galvanic cathodic protection is a common corrosion control technique that is employed in applications from home appliances to boats to bridges. At its core, however, galvanic cathodic protection is simply an electrochemical cell---that is, a battery. This presents an opportunity to treat this corrosion protection as an in-situ power source that by definition will last as long as the protection system itself. In this paper, we explore the efficacy of these pervasive, "ambient galvanic cells" as potential energy harvesting sources. We then show how to use these cells as a power source for wireless sensing devices that monitor the health of the same corrosion protection system. Our system takes advantage of newly available LPWAN technologies that allow for effortless wide-area coverage. We demonstrate the viability and efficacy of the system on one of the most common galvanic cathodic protection systems, home hot water heaters. We show that this technique can be a powerful new asset for corrosion monitoring and for deploying wireless sensor networks broadly.