Developing Microbial Fuel Cells for Remote Power Generation
What do deep-sea bacteria have in common with your refrigerator? Both are the subject of CEE research efforts concerning energy generation and use, and may become key factors in the way we think about energy. In the face of climate change concerns coupled with a rising demand for power, researchers are striving to develop energy technology that will meet consumers’ needs while preserving the health of the environment. By tackling energy challenges from numerous directions, CEE researchers can give communities the tools they need for the sustainable generation and use of energy.
Below is part one of a four part series looking at how researchers in Civil and Environmental Engineering are examining how we can generate and use energy more efficiently. This story was originally published in the winter 2013 issue of the CEE News magazine.
A bacteria-powered fuel cell has been busily running in CEE Associate Professor Kelvin Gregory’s office refrigerator for the past six years, but Gregory doesn’t seem to mind. Gregory’s recent research, done in collaboration with Professor of Mechanical Engineering Phil Leduc, centers on the utilization of electricity-generating bacteria in remote, self-powered electricity generation, and the fuel cell is a testament to the project’s success.
A fuel cell is a device that physically separates a chemical reaction into fuel production and oxidization, producing an electric current. Gregory studies microfluidic fuel cells, in which the two reactions are separated by fluid moving slowly through small channels. Having researched fuel cells during his post-doctoral work, he decided to pursue the topic further at Carnegie Mellon. He was aware that a particular species of bacteria called Geobacter could produce electricity, and wanted to approach this unique feature from a technological standpoint: could humans combine the electricity generation capabilities of these bacteria with microfluidic fuel cell technology?
To address the question, Gregory set out to develop a tiny fuel cell that could be powered by bacteria. The project was based on previous experimentation with a crude fuel cell composed of a wire half-submerged in ocean floor sediment. As electricity-generating bacteria in the sediment colonized an electrode on the submerged end of the wire, the electricity they produce traveled through the wire to an electrode on the opposing end. Using these “sediment batteries” as a framework, Gregory was able to develop a fuel cell that is only 0.3 microliters in total volume, making it one of the world’s smallest fuel cells. (For reference, the average raindrop is over 300 times this size.) “There is an enormous amount of energy that is accessible by bacteria,” he explained. “By putting the correct bacteria into a fuel cell, we could ensure a remote source of electricity that would be inexhaustible as long as the cells are alive.”
Microbial fuel cell technology is ideal for small-scale electricity generation in environments where using conventional batteries is prohibitively expensive or dangerous. For instance, the cells could power sensing devices that monitor corrosion and pressure levels in deep-sea oil and gas pipelines. And the applications aren’t limited to the ocean floor; Gregory envisions microbial fuel cells powering medical devices such as glucose sensors implanted in humans.
Gregory believes microbial fuel cells will play a unique role in energy production. “You won’t see microbial fuel cells powering a city,” he said. “But when it comes to remote electricity generation in places where humans should not or cannot reach, microbial fuel cells have a huge advantage.”