Microbial fuel cells are considered a source of sustainable energy. Why?

1. They use living organisms ass catalysts to generate electricity from certain substrates.
2. They use a variety of inorganic materials as substrates.
3. They can be installed in waste water treatment plants to cleanse water and produce electricity.

Which of the statements given above is/ are correct?

A microbial fuel cell is a device that converts chemical energy to electrical energy by the catalytic reaction of microorganisms. Among the electrochemically active bacteria are Shewanella putrefaciens, Aeromonas hydrophila. Mediator-less microbial fuel cells can, besides running on wastewater, also derive energy directly from certain aquatic plants. Virtually any organic material could be used to feed the fuel cell, including coupling cells to wastewater treatment plants.