System Design and Operation: Benthic Microbial Fuel Cells
Project Lead: Jordon Beckler, Ph.D.
Affiliated Home Campus: Harbor Branch
Affiliated Department: Harbor Branch Oceanographic Institute
REU Scholar: Brandon Kelly
REU Scholar Home Institution: Milligan University
PROJECT
For centuries, man has used the energy stored in once-living hydrocarbons in order to provide light, transportation and information. Unfortunately, these resources are being rapidly depleted and their long regenerative timescales are leading to an imminent energy crisis. Alternatively, an emerging renewable technology, Benthic Microbial Fuel Cells (BMFCs), allow for sustainable energy production from still-viable microbes in marine and freshwater sediments. While the power production from current BMFC technology does not yet rival that of other renewable peer technologies (e.g. solar, wind, or wave/tide/currents), they provide a low cost and low impact method for extracting power from the seafloor. In particular, they are therefore suitable for powering sensor platforms rapidly expanding within the “blue economy”. Whereas traditional power sources require sensors to be tethered to a grid (or the surface ocean) or rely on the finite energy of a battery, a BMFC based solution can be deployed remotely, at the point-of-use, for extended durations. For example, previous researchers have powered common conductivity, temperature, and dissolved oxygen sensors for over a year, solely using a BMFC (and batteries that were pre-charged but maintained in-situ by the BMFC). A number of additional benefits also include the ability to remediate toxic contaminants, including organics and heavy metals, in wastewater and runoff via redox processes fundamental to BMFCs. Due to their low cost and ease of construction, they also serve as an excellent opportunity to enhance renewable energy education curricula. In turn, my summer project focused on 1) harvesting the energy from the fuel cells for low power sensor networks and 2) authoring a manuscript that guides educators in implementing BMFCs in the classroom. For (1), I built and tested several fuel cells (both marine and freshwater) and developed electronics to monitor and harvest power. While not a serious power grid solution, the BMFCs did reach a maximum power density of 18 mWm-2, enough to power several types of marine sensors with a fuel cell footprint of 1 m2. In order to harvest this power, a combined step-up/charger IC was used to upregulate the voltage to enable safe charging of a LiFePO4 cell. For (2), we authored a manuscript draft to be submitted to IEEE Transactions on Education that describes the use of BMFCs in teaching engineering, chemistry, and ocean science in the context of renewable energy. Overall, my work continued to advance our lab’s goal of developing low-cost and scalable solutions for providing renewable and potentially environmentally beneficial energy solutions.