Bacteria are not normally regarded as renewable energy sources. When people think of bacteria, they will have images of microscopic critters that can cause diseases. Many bacteria do cause diseases. But there are also good and useful bacteria. One emerging use of bacteria is in the research about how to make hydrogen fuel. Technically, bacteria are not the source of energy. But with their ability to break down organic matter to produce fuels such as methane, ethane, and hydrogen, bacteria are becoming more viable means of producing alternative fuels.
Can bacteria really produce energy? Bacteria do not purposely produce fuels for the benefit of mankind. They simply consume organic wastes. By “eating” these wastes, the bacteria expel their own wastes, which humans consider alternative fuels. The process of using bacteria to produce these fuels out of bio-matter is simply called bio-fuel conversion. Bio-fuel conversion is not a new technology. Bacteria and other microorganisms have been used to produce fuel out of seaweed, corn, coconut oil, poultry wastes, and other organic-based materials. 
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Bio-fuels, however, were deemed not feasible because there is a fear that farmers would plant corn to make fuels instead of selling the corn as food. Obviously, a world abundant in energy but lacking in food is not welcome. But with an impending severe global energy crisis, the idea of creating alternative energy from bacteria is being revisited. Organic wastes, after all, have the same atoms as the ones that make up fuels. One bacterium under study is the Escherichia coli and its ability to break down chocolate wastes to produce hydrogen.