microbial fuel cells are a potential source of green energy, producing electricity without combustion while cleaning wastewater. but, before industry builds commercial facilities, researchers must carefully assess the production capabilities and engineering designs of biofilm reactors. the northwestern university research identified a design issue that could bear significantly upon reactors’ production capacity.

the findings also highlight the ability of scientific computing to complement laboratory research. laboratory experiments cannot reveal the small-scale structure of biofilms or other precise information related to microbial fuel cell power production. nor can they explain the sharp decrease in power production that occurs as biofilms mature.

to address this gap, researchers simulated the fuel-cell activity using mathematical models. they discovered that the biofilm overgrowth can lead to power loss. the images at right show how even slight bacterial overgrowth can lead to regions in the reactor with drastically reduced power production.

the initiative for sustainability and energy at northwestern university did the computer modeling in collaboration with laboratories at arizona state university and the university of wisconsin, milwaukee. the research serves as an example of how mathematicians, scientists and engineers can combine their talents to solve challenging problems.

project description: power field monitoring equipment from wetland detritus materials using microbial fuel cell

objective:

detritus or organic matter stored in forest / wetland / estuarine ecosystems represents a large potential source of energy. microbial fuel cells (mfc), which can convert organic wastes into electricity, are a potential tool to harvest this renewable energy to power field equipment in remote areas. spatial and temporal variations of organic substrate and redox conditions, as well as power output and stability are the major challenges in designing an in-situ mfc system for practical application. the ultimate goal of this study is to design an in-situ mfc system that can produce energy to power field monitoring equipment.

approach:

both batch and continuous mfc in controlled laboratory environments will be built to evaluate the effects of quantity and composition of dissolved organic matter, salinity, temperature, depth of soil, and water level on the power output of mfc. in addition, in-situ mfc systems will be installed in a healthy freshwater and a salt-water stressed forested wetlands in winyah bay, south carolina, to examine forest structure, evapotranspiration, seasonal, and tidal factors on the performance of mfc. the stability of voltage, density of current, and internal resistance used will be recorded to analyze the performance of mfc.

expected results:

the data from both laboratory and field experiments will provide useful information to assist designing an in-situ mfc system that uses detritus materials to achieve constant and useable electric energy output. the in-situ mfc systems installed in the forested wetlands at winyah bay can serve as educational and demonstrational projects to local schools and communities about the concept of sustainability and renewable and alternative energy.

(from the epa p3 website)