Climate change is closely related to carbon emissions. Since a large portion of carbon emissions produced by humans is related to consumption of fossil fuels, research on alternative energy generation is also related to climate change.
Microbial fuel cells are devices that can be used to convert the energy contained in organic matter into electricity through the activity of microbes. Some bacteria that live in the absence of oxygen are able to pass electrons that they extract from organic matter (food) to a solid electron acceptor outside the cell, such as an iron mineral. This is a form of anaerobic (oxygen-free) respiration. When an electrode is placed near this kind of microbe, it can act as the electron acceptor (anode). If the anode is connected to an electrode (cathode) placed in an aerobic environment (containing oxygen) and some H+, the electrons can be passed from the cathode to the oxygen, producing water. The current of electrons produced as they move from the anode to the cathode can be harnessed to do work. The process is shown below.
Many organic carbon sources can be used to fuel the process.
The inset picture shows a fuel cell made by an undergraduate researcher to generate energy from aquaculture waste. Other sources of cheap organic matter include feedlot, dairy farm, swine and human wastes. The fuel cell not only produces energy, but it reduces the amount of harmful oxygen demand in the waste making it easier to dispose, and reduces the energy requirement to treat the residual.
This technology could significantly reduce the cost of waste treatment while reducing our dependence on fossil fuels.
significantly reduce the cost of waste treatment while reducing our dependence on fossil fuels.