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

1. They use living organisms as 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?

Microbial fuel cells (MFCs) are bioelectrochemical devices that harness the metabolic activity of microorganisms to convert chemical energy directly into electrical energy.

• Statement 1 is correct: MFCs use living organisms (typically bacteria) as biocatalysts to break down substrates and release electrons, thereby generating electricity.
• Statement 2 is incorrect: MFCs predominantly use organic matter (such as carbohydrates, proteins, or organic waste) as their primary energy source. While some specialized microbes can oxidize specific inorganic compounds, MFCs do not generally rely on a "variety of inorganic materials" as substrates.
• Statement 3 is correct: A highly beneficial application of MFCs is in wastewater treatment plants. The bacteria consume the organic waste present in the water, effectively cleansing it while simultaneously producing renewable electricity.

Therefore, only statements 1 and 3 are correct.