Navy, Marine Corps Tests Autonomous Zero-Power Bathythermograph Sensors

U.S. Naval Research Lab Press Release
June 27, 2011

Developed by the Naval Research Laboratory Bioenergy and Biofabrication Section in the Chemistry Division and the Physical Acoustics Branch of the Acoustic Division, the Zero Power Ballast Control (ZPBC) is a technology that relies on microbial energy harvesting developments to enable unsupervised underwater sensing with subsequent surfacing and reporting capabilities.

With an ultimate goal of producing simple, small, power-efficient data harvesting nodes with variable buoyancy the device will be able to monitor ocean temperatures with a stay time ranging from weeks to months and eventually years, providing a longer term than other mechanisms such as the Expendable Bathythermograph (XBT).

"Preliminary trials were successful in many ways," said Dr. Justin Biffinger. "The device surfaced and submerged periodically as designed via hydrogen gas produced from the microbial inoculum and growth medium, proving the device generated gas in sufficient quantity to produce buoyancy."

During testing of two ZPBC systems, the rise and fall of the devices were supported by on-board pressure and temperature sensor data and direct observation. The bacterial fuel source (inoculated gas production vessel) was then attached and the two ZPBC devices were deployed in situ off a military pier in Sattahip, Thailand, and held in place by mooring lines for seven days.
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