Beer batteries create energy from bacteria that feed on waste water. The technical term for them is "microbial fuel cells" (MFCs), and they earned the nickname beer batteries because beer company Fosters has funded the development of MFCs in Australia that run on waste water produced by the beer-making process. The best part about beer batteries, though, is that you can make them at home, based on instructions developed by a high school student named Abbie Groff. She won an international science fair prize for her work. Image by Abbie Groff.