One man’s trash is another man’s treasure.

Source: Xing Xie et al. 2013

More than 80% of our energy is derived from oxidizing fossil fuels, a nonrenewable resource that emits harmful greenhouse gases into the atmosphere. However, what we consider waste might actually be a useful biofuel. An alternative source can come from marine sediments, wastewaters, and biomasses considered as waste. These sources have not been touched and biodegrade to produce greenhouse gases. Therefore, it is useful to recover the energy of these organic reservoirs and convert them into usable fuel. This is done using a microbial battery. It contains an anode and cathode to extract energy and generate fuel. The anode oxidizes the organic reserves, while the cathode regenerates the fuel. A draw back of using these silver-based electrodes includes the high cost for large-scale applications. (Xing X. et al. 2013)

Reference:

Xie, Xing, Meng Ye, and Po-Chun Hsu. "Microbial Battery for Efficient Energy Recovery." Microbial Battery for Efficient Energy Recovery. Proceedings of the National Academy of Sciences of the United States of America, 09 Aug. 2013. Web. 24 Sept. 2014.